Tomatoes

Solanum lycopersicum

Thousands of years ago, tomatoes were common in South America and Mexico and were used in cooking more than eaten raw.

Introduction

Thousands of years ago, tomatoes were common in South America and Mexico and were used in cooking more than eaten raw. They were first brought to Europe by the Spanish conquistador Cortés, in the 16th century.

Tomatoes are in the Solanaceae or nightshade family, and this caused them to be viewed with suspicion in Europe for some time. Unripe fruits and leaves contain tomatine, which would be poisonous if eaten in large quantity, but ripe fruits contain no tomatine.

In the UK, one of the first people to grow a tomato plant was John Gerard the surgeon, who wrote in his Herbal of 1597 that the fruits are unfit for human consumption. It was another 200 years before tomatoes were in widespread use.

Mid-August vegetables, which I entered in competitions at Bruton Horticultural Society in 2015 – Marmande and Matina tomatoes on the left; Rosada, Sungold and Yellow Brandywine on the right

Harvest period

Days from seed to first harvest: 90, often more.

Best climate has warm summer days of 22–35 °C/72–95 ° F, and at least four months between last and first frost dates.

2nd July – first tomatoes of the year were Garden Pearl in this pot, on staging in the greenhouse, sown in mid-March

12th July – three delicious cherry tomato varieties grown in the greenhouse: Rosella, Sungold and Garden Pearl; I had not yet picked any beef tomatoes by this date

Early August colour and beauty – tomato, carrot, beetroot and cucumber

‍

Why grow them

Great flavour, colour, abundant fruiting over many months, a range of plant and fruit sizes – there is much to like about tomatoes. Tomato plants grow well in warmth but also tolerate a certain level of coolness, more, for example, than aubergines and peppers.

They can be grown in many ways and you can fit them into almost any growing situation.

You can choose from a huge range of varieties, for the fruit size, colour and flavour you like. They will compare favourably to most tomatoes of commerce!

Tomatoes with much less flavour happened from the 1950s, after a phenotype (genetic trait) was discovered that enabled breeders to ensure uniform ripening. The tomatoes were of even colour all around, with no green top (greenback), but unfortunately also had reduced sugar and taste levels.

Well-grown tomatoes are a source of umami flavour – savoury. The other six main tastes are sweet, salty, sour, bitter. astringent and pungent.
Use of salt increases umami tastes, hence the increased flavour of tomatoes with salt.

Fruit or vegetable?

Botanically, tomatoes (also cucumbers, peppers etc.) are fruits or berries. However, in general usage we call them vegetables because their sugar content is much lower than that of fruits.

Another way to clarify this difference is to ask whether you eat a food as part of the main course or as a desert. Tomatoes, cucumbers etc. are eaten with the main course – they have a savoury rather than sweet flavour and therefore are vegetables.

In South West France, August 1997 – sliced Mami tomatoes (see ‘Varieties’ below) in a beef tomato salad

Black Russian, Brandy Boy F1 and Yellow Brandywine in early September

One large beef tomato that weighed a half kilo/1 lb; after dehydration it weighed 27 g/1 oz

Pattern of growth

Different varieties of tomato plants grow small or large, and tall or bush. Results vary according to whether you grow them outside or under cover. This guide concentrates on the latter because it is based around my experience of growing tomatoes in cool summers, where there is often not enough time for plants to give a worthwhile harvest of ripe tomatoes outside.

Plants grow for three or four months before they produce worthwhile amounts of fruit.
During summer, tomato plants put on a phenomenal amount of growth: 1) creating new stem and leaf, 2) developing trusses of new fruits, 3) ripening tomatoes. They are doing all three of these things, each of which needs a lot of energy, at the same time!
Plants are killed by the first frost of the autumn, and often before that their growth has slowed in the darker conditions.

Tomato types

Bush plants are called determinate and are annuals – they ‘crop then stop’, without trailing stems.
Cordon plants are called indeterminate and are perennials, as long as there is no frost in winter. Their natural habit is trailing. We grow them as annuals, vertically upwards with support.
Cherry tomatoes are usually sweet and small, although often larger than a cherry in size, with a corresponding reduction in weight of harvest compared to beef tomatoes. They ripen quite early, especially Sungold and some determinate varieties.
Beef tomatoes are the largest in size and have fewer cavities in the fruit, therefore contain more flesh and proportionately less skin. The texture is often dense (meaty, hence the name) and full of flavour, but they ripen later than cherry tomatoes.
Medium-sized tomatoes with firm skins are most common in stores and supermarkets, often of a variety selected for yield ahead of flavour. Mostly they are grown hydroponically for maximum harvest, to pay the bills – the price of tomatoes relative to other goods has declined steadily in the last 60 years.

You can grow hydroponically at home, but this requires a fair amount of kit. I do not recommend it unless you have sufficient time to monitor all the variables. It needs more knowledge and investment compared to growing in soil or containers. Your harvest will look good, but is missing important nutrition from soil microbes.

Brix, a measure of sugar

A way to measure sweetness is called brix, and uses a refractometer. Brewers and winemakers keep this device handy to check the sugar content of their must, which tells them how much alcohol there will be after fermentation.

I have used a refractometer over a few years, with the juice of different tomatoes grown in different ways – the table below gives an idea of their sweetness. Higher figures mean more sugar.

The highest figure I secured was a fully ripe Victoria plum at 19.4. Here, beetroot and carrots are 8 or 9. The table offers clues about how to increase tomato sweetness: reduced watering is the main one – this is easier in pots or containers than in soil outside if it has rained. Choosing suitable varieties clearly influences flavour.

Brix is sometimes claimed to represent nutritional quality, with higher numbers indicating more nutrition. This is not totally proven, but higher numbers certainly indicate reduced water content, and therefore you have denser food with more dry matter.

The same weight!! 1 kg/2.2 lb of beef tomato and 1 kg/2.2 lb of Sungold and Suncherry

19th August – a weekly harvest from 17 plants of beef tomato: 6.7 kg/14.7 lb, and 17 plants of cherry tomato: 2.2 kg/4.8 lb

30th September – polytunnel tomatoes with no feeds given; soil was mulched with compost in May

Under cover

Inside a structure you have the possibility of growing indeterminate plants up strings – this increases harvests a lot. I refer to these plants as cordon tomatoes.

In areas with cooler summers, growing under cover gives much more chance of worthwhile harvests, in summer as well as in autumn.
When summers are hot and long enough, tomato stems have time to grow longer than a structure is high. You need a device to hold spare string, which enables repeat lowering of the now-empty lower stems down to soil level.
The active flowering and fruiting zone of cordon tomato plants spans roughly 1.8 m/6 ft. Below that level are non-working leaves and finished trusses.

Plants grown under cover can be kept dry, which is a huge advantage in damp climates because it prevents late blight. Your key knowledge is that late blight cannot develop on dry leaves – see below.

Tomato plants grow like weeds – this photo shows tomato roots growing into fresh, day-old horse poo, 17 days since I potted a plant into it

A huge yield of beef tomatoes from these plants, but quite late in the year – this is 2nd September in the polytunnel

The final truss of Brandy Boy F1 tomatoes at the top of my greenhouse in early October

Outdoors

There is more wind outside and indeterminate tomato plants need tying to strong stakes. There is a fair amount of time needed for securing them.

Bush plants are quicker and easier to grow than cordons outside, but take longer to harvest and fruits on the ground may be damaged by slugs; also, leaves may stay wet and suffer late blight.

A garlic and tomato interplant outside in the Small Garden on 29th May – it is 11 days since we planted the tomatoes; the garlic has been growing since October

27th June – now five weeks since we transplanted the tomatoes and two weeks since we harvested the garlic, with onions close behind

27th July – Small Garden tomatoes outdoors in the fine summer of 2018: Dorada is closest and Primabella are the red ones beyond

Suitable for containers/shade?

Tomatoes are the container vegetable par excellence. The main criterion is a container large enough to grow the variety you choose – cherry tomatoes are most successful. Site in sun where possible, unless your summers are hot.

You need a compost with plenty of nutrition. The photos below illustrate what happens to plants when they run out of food. It’s not the end of the world and you still get a harvest, but it’s smaller and finishes sooner.

Bush tomatoes, unrecorded variety, just transplanted in a compost trial and with no feeding – 29th May 2011 at Lower Farm

A tomato trial in the same order on 19th October – from left to right: old cow manure, homemade compost, old horse manure, Moorland Gold potting and mushroom compost

‍

Outdoor tomatoes on 30th August during a dry summer; these had some Osmo feed every week for four weeks

‍

There are many proprietary foods available for tomato plants. You need a feed for container growing, compared to the little or no feeding needed for plants in soil. Also watering is much more frequent than for tomatoes growing in soil, where the root run is more extensive.

Make sure you have the time and means to water regularly. There are proprietary watering kits with pipes and timers, but that investment may well not be repaid in the value of your harvest, depending on how you calculate it.

Large containers can grow cordon tomato plants with stakes inserted in the container. Or you can grow special varieties for hanging baskets. Do try a few things!

31st August, in the trial above – this is the pot with cow manure and no feed given

31st August, in the trial above – this is the pot with mushroom compost and no feed given

Maskotka bush tomato plants on 11th August, trailing stems from container plants on shelves; in the distance are cordon Yellow Brandywine

Varieties

My favourite varieties reflect the growing conditions here – summers warm but not hot, with the risk of late blight outside and five months between last and first frost.

In warmer climates, I would favour beef tomatoes over cherry tomatoes. In cooler climates, look for fast-ripening varieties.

Sungold F1 ticks every box – it crops early and tastes amazing, plus can be grown outdoors in sheltered gardens. The yield is not heavy and the skin is prone to splitting.
Sungella F1 is a larger version of Sungold, with more harvest and less flavour.
Sakura F1, a red cherry, offers great flavour and larger fruits than many cherry varieties.
Gardeners Delight was an early commercial cherry tomato variety in the 1970s, when it was smaller and sweeter than it is nowadays. The varietal maintenance has not been thorough because there is more money made from selling hybrid tomatoes. My last two attempts at growing Gardeners Delight resulted in medium-sized fruit with very average sweetness and tough skins.

6th August in a cool summer – Sungold is ripening reliably, when other varieties were much slower to ripen

Sakura in the centre and Rosada on the left are both F1 – 26th August, again in a cool summer

Sungella is less aromatic than Sungold, but with good flavour and it’s highly productive – 26th August

‍

Crimson Crush and Mountain Magic, both F1, resist late blight without being immune to it and have decent flavour. Crimson Crush is a medium-sized beef tomato.

I have had top results from open-pollinated cherry varieties offered by Culinaris in Germany. Resi, Primabella, Primavera and Dorada all have good flavour. They grow well in cooler conditions and have some resistance to late blight.

Dorada tomatoes outside in the Small Garden on 16th August 2018, during a hot and dry summer

30th August – Small Garden tomatoes Dorada, Sungold and Crimson Crush, in the less hot summer of 2019

30th August 2019 – outdoor-grown tomato Crimson Crush F1 is a tasty cordon variety with resistance to late blight

Beef tomatoes grow better under cover, in cooler climates.

Black Russian has a rich flavour, soft skin and deep colour. It’s not really black, just purple. I tried Indigo Rose once, which is sold as a ‘black tomato’, and found it tough-skinned with little flavour.
Brandywine tomatoes are large and taste wonderful – there are red, pink and yellow varieties.
Super Marmande is an old variety from South West France, of variable quality according to who has been selecting the seeds. The flavour and texture are superb, fruits are medium-large. Possibly these were the origin of the huge beef tomatoes I found in a neighbour’s garden in South West France, which we called Mami tomatoes in honour of the old grandmother who grew them every year.
Hybrids such as Gigantonomo, Big Boy, Country Taste and many others, have been bred for the exceptional size of their fruits. All of those that I have grown and eaten also taste good!
Feo de Rio and Feo de Rigordo grow super tasty, red beef tomatoes of dense texture and top flavour.

Dense texture in the 1 kg/2.2 lb beef tomato Feo de Rio Gordo – 2nd October

With a Feo de Rio Gordo in late September – this tomato weighed 1 kg/2.2 lb

Berner Rose is a top flavoured beef tomato, which needs a warm summer to fruit well – this is 7th October

Vintage Wine tomato in early September, from the polytunnel

Harvest of 12th September from the polytunnel: Orange Kiss pepper, Country Taste F1, Purple Ukraine, Yellow Plum, Marmande, Black Russian and Orange Wellington F1

Ferline F1 in the polytunnel in mid-September – it yields well but has average flavour

‍

Commercial tomato varieties are mostly red and of medium size. They have tough skins so that they transport well, plus have a long shelf life. Their water content is high because this results in a high yield for making a profit. Do look at the brix result of Velocity in the table.

Orkada Fi tastes better at least.
A medium-sized red fruit of decent flavour is Matina.

Matina in the polytunnel in late July, showing leaf roll (see ‘Diseases’ below) but fruiting well

Orkada F1 tomato is high yielding and of average flavour – in the polytunnel on 16th August

Velocity F1 in the polytunnel on 6th August, bearing large fruits of average flavour, again with rolled leaves

Video

Tomatoes in three locations, over three months

Sow and propagate

In the UK at least, there is something of a race to sow tomato seeds as early as possible. Although this may result in earlier harvests, it often also results in extra work and space needed, to look after plants until conditions are good for transplanting. As it happens, I am writing this on the 8th March when the temperature overnight here for two nights has been -5 °C/23 °F, and there are many posts on social media of people who have lost their early-sown tomato seedlings, in an unheated greenhouse for example.

Seeds germinate in six to nine days.
In cooler climates, germination is successful when you give warmth. It does not need light.
Raising seedlings is most successful with full light; the temperature can be lower than for germination.
Plants are killed by frost at any stage of their growth.

Sowing time

Light and warmth are easier to provide when sowing is not too early. Any time in early spring is good and my favourite time is mid-March, for eventual growing under cover.

For outdoor tomatoes, sow two weeks later. I sow early April under cover, to plant out in the third week of May, after our last frost date.

Tomato seedlings on 30th March, sown a week ago in potting compost with 50% vermiculite

Tomato seedlings before pricking out on 2nd April, in potting (not seed) compost

Latex module tray with direct-sown tomato seeds, whose variable germination means empty modules

Sowing method

Sowing can either be in a small tray to prick out, or in small (say 3 cm/1 in) modules of multipurpose compost. For sowing in a tray, which drains less well than module cells, best use a seed compost (not John Innes, the quality has declined) or add 50% vermiculite/perlite to a potting compost. Some potting compost can work as seed compost – the main criterion is good drainage. A high level of nutrients does not inhibit germination.

Seed trays need less space than module trays, during the first two weeks. Hence it’s efficient to raise many seedlings in a small tray, for eventual pricking into modules. Every module cell then has a seedling, compared to the occasional gaps that result from sowing in modules and a few seeds not germinating.

Tomato seeds need a temperature of around 15–20 °C/60–68 °F to germinate evenly. Therefore a warm room in your house is fine during the first week when it’s all about temperature, not light.
Then give them a week or two on a windowsill, for light as well as warmth.
After that they need to be in full light, to prevent stems from growing long and thin.

About two weeks from sowing, if your seedlings are in a seed tray, use a pencil or an equivalent tool to gently lift them out from below root level. Always hold them by the leaf, which risks less damage than holding them by the stem. Make a hole for each seedling in module cells of compost, and push the roots of seedlings into this compost, one per cell. It’s fine to bury the stems.

Nights may be too cold in any outdoor structure during early spring. You can avoid difficulties in various ways:

Sow later, unless you can provide the necessary protections and extras.
You probably need some heating for frosty nights in your full-light option outside, such as a greenhouse or polytunnel. An electric heat mat is useful for this.
Or it may be sufficient to lay fleece over seedlings before any frosty night – double thickness.
Grow lights are an option if you continue to grow seedlings in the house; you also need to have a watering method, such as a capillary mat, for bottom watering.
Without a grow light, plants by a windowsill grow long, thin stems and then fall over. This is more likely when you sow too early.

To keep tomato plants sturdy and strong, don’t overwater them. There is no need to feed at this stage.

Pot on?

This is worthwhile for seedlings, because tomatoes are six to eight weeks old before transplanting. I find that this age of transplants works well here, where the spring is quite slow. In climates where spring is brief and then quickly hot, your transplants could be just four to five weeks old.

Pop out module seedlings when they are starting to crowd together in the module tray, before they develop stems that are too long and thin.

Place each module rootball quite deeply in a 7 cm/3 in pot by mid-April, and then move the rootball from its 7 cm/3 in pot to a 10 cm/4 in pot two weeks after that.
Or pop module plants into a 10 cm/4 in pot, to save one potting process. However, this uses a little more space in your propagating area.

The hotbed on 4th April, with leeks and basil just sown and tomatoes pricked out in the centre, as well as buckhorn plantain

The hotbed in mid-spring, on 12th April – tomatoes 25 days since sowing, basil 10 days, and celery recently pricked out

Recently potted aubergine and module-sown tomato plants on 13th April

Transplant/interplant

Same soil? Rotation?

This is pertinent for those of us growing plants in the soil of an under cover space every summer. For how many years is it possible, without a damaging buildup of pest and disease? There are many variables to consider, which means that no simple answer is possible.

No dig, and a surface mulch of high-quality compost, increases your chances of successful growth every year.
Tomato pests increase in the soil, which may result in plants being smaller and less healthy. One remedy is to buy plants grafted onto rootstocks that resist soil pests.
The main soil pest to worry about is root-knot nematode – see below.
Diseases do not accumulate; it’s often thought, for example, that spores of late blight can somehow linger through winter and then establish on plants again in the spring, but they cannot – see ‘Diseases’ below.

27th July – tomatoes in the greenhouse are the eighth summer in the same bed, with no rotation

The end of August – polytunnel tomatoes are in these beds for the second year in the same soil, where there was a lot of late blight just twelve months earlier

Transplant size and time

The ideal size is 20–30 cm/8–12 in high plants, ready just after the last frost date, or perhaps a week before that for growing under cover. However, your plants may be ready before the ground is. Perhaps there is something still growing from the winter, or the weather may be unusually cold.

Plants kept in their pots for too long lose the green leaf colour, with lower leaves turning yellow and even brown. Stems elongate and toughen.

Fortunately, you can still transplant such plants – tomatoes are incredibly strong.
The main drawback is that you will have lost time; a second one is loss of propagating space.
Make a note of the timings, because this suggests that you sowed too early.

From a sowing on 20th March – this is just 40 days later after a warm April, and these plants are ready to transplant, ahead of schedule

Late April – an interplant of a new tomato between chard for salad, which is soon to finish; it’s not that chard is a great companion for tomatoes, more that their patterns of growth are not interfering with each other, from the timings here

Transplant method

Bury the lower part of tomato stems, both when pricking out and transplanting, to keep them sturdy. When setting in the ground, use a trowel to make the hole, a little wider than each plant’s rootball and around 5 cm/2 in deeper. Push the rootball in firmly and give a good watering at this point.

See ‘Support’ below for information on how you may want to pop a string in the hole before planting.

In the polytunnel – an early planting of tomatoes on 29th April; it was then fleeced over, ahead of probable frost outside – unlikely, but possible under cover

Tomatoes just planted with string under their roots, and French marigolds with garlic sown in October

12th May – the polytunnel half planted for summer, with tomatoes this end, either side of the garlic which finishes in one month; we spread the annual dose of compost before summer planting

Inter- and companion plants, flowers especially

Carrots are famous for having an affinity with tomatoes. You might, for example, have a sowing of early carrots in a polytunnel, between which you plant tomatoes in gaps that increase each week as you harvest carrots. Then, within a month, the carrots are finished and you have tomatoes growing. See Lesson 15 for how I did this with cucumber plants, and Lesson 6 with Brussels sprouts – both lessons in Course 3A.

Alliums grow well with tomatoes. Either grow early spring onions, between which you transplant summer tomato plants, or transplant late spring onions between tomato plants that will finish in a month or so.

A lovely rule of thumb for companion planting is that vegetables grow well together as plants when their harvests taste good together, as long as the companion plants do not grow too large and are not maturing by early autumn, when tomatoes need full use of the soil. Hence onion, garlic, basil and parsley make great companions for tomato plants.

An excellent flower to grow, with cordon tomatoes especially, is any kind of dwarf marigold. The growth habit is compact and low to the ground which complements the taller tomato growth. Many marigolds secrete a substance called limonene, whose smell deters aphids.

‍

Mid-April – tomato and marigold seedlings, which were sown at almost the same time

12th August – tomatoes and marigolds in the same place in the polytunnel for the second year

Mid-September – dwarf French marigolds cover the ground nicely among cordon tomatoes

Spacing

Spacing both under cover and outside is 45–50 cm/18–20 in, no closer. This allows room for growth over a long period.

There is air around all leaves to reduce the risk of blight.
Space makes it easier to manage growth and pick the fruits.

Support

If using a string to support cordon plants under cover, place one end of the string in the hole before planting. Best pre-tie a knot, on the end that is under the rootball, otherwise there is a small risk of the string sliding up and out of the hole once plants are bearing a lot of weight.

Do not use jute or any natural fibres for this, because they would rot and break. Use polypropylene, which can be reused the following year.

Outdoor plants to grow as cordons can have a stout bamboo placed close to the rootball. Make a first tie when about 30 cm/12 in high, and then tie the stem to your bamboo every 15–20 cm/6 –8 in.

Rosada F1 showing its stem, which has been supported by us twisting it around the buried string

Yellow Brandywine – 20 in/50 cm between plants but with no spare height because of the polytunnel hoops curving inwards

Late July – canes for Small Garden tomatoes outside have plenty of height, but the summer is too short and windy for them to grow more; in ten days I shall pinch out the tops

Raise plants from sideshoots!

Same soil? Rotation?

No dig, and a surface mulch of high-quality compost, increases your chances of successful growth every year.
Tomato pests increase in the soil, which may result in plants being smaller and less healthy. One remedy is to buy plants grafted onto rootstocks that resist soil pests.
The main soil pest to worry about is root-knot nematode – see below.
Diseases do not accumulate; it’s often thought, for example, that spores of late blight can somehow linger through winter and then establish on plants again in the spring, but they cannot – see ‘Diseases’ below.

Transplant size and time

Plants kept in their pots for too long lose the green leaf colour, with lower leaves turning yellow and even brown. Stems elongate and toughen.

Fortunately, you can still transplant such plants – tomatoes are incredibly strong.
The main drawback is that you will have lost time; a second one is loss of propagating space.
Make a note of the timings, because this suggests that you sowed too early.

Transplant method

See ‘Support’ below for information on how you may want to pop a string in the hole before planting.

Inter- and companion plants, flowers especially

‍

Spacing

Spacing both under cover and outside is 45–50 cm/18–20 in, no closer. This allows room for growth over a long period.

There is air around all leaves to reduce the risk of blight.
Space makes it easier to manage growth and pick the fruits.

Support

Do not use jute or any natural fibres for this, because they would rot and break. Use polypropylene, which can be reused the following year.

Outdoor plants to grow as cordons can have a stout bamboo placed close to the rootball. Make a first tie when about 30 cm/12 in high, and then tie the stem to your bamboo every 15–20 cm/6 –8 in.

Water and feed

How often to water

Tomato plants grow so fast that they need a lot of water, but for plants rooting in soil it does not have to be every day. We water every other day in hot sun and twice a week in cloudy weather, at 51 degrees latitude and in moist, temperate conditions. In hotter climates, daily watering is good.

For new plantings in dry weather, give water every day or two, just around their rootball. After a week, you can water less often, assuming there is moisture in the soil from winter.

It’s good when the soil or compost surface is dry between each watering.
Container plants need watering daily, even twice daily once plants are large, and in hot conditions.

14th May – daily or twice daily, plants of this size in pots need a lot of watering because their root run is so contained

One option for watering in the polytunnel – these are 12 l/2.6 gal cans and I am watering basil near the tomatoes

‍

How much

Watering is a skill to learn, because overwatering can depress growth by causing too little air around roots. Also, you are wasting time and water.

A rule of thumb is that larger plants and hot conditions mean more water is needed.
By late summer, reduce both frequency and amount, to discourage new growth.
During early autumn (September here), for plants both under cover and outside, you can almost stop watering plants in soil. Continue to water containers, but less.

Under cover, a final watering can be about mid-September. This helps plant metabolism to switch from growing stem and leaf towards ripening of fruit.

With reduced watering at the stage that many fruits are ripening, their sweetness increases.

Extra mulch to retain moisture?

Any mulch of organic matter helps to reduce watering, but plants keep sucking moisture whatever mulch you use. A thick mulch does not mean you never need to water and it could soak up the moisture from a summer shower, making it less easy for plant roots to access new rainfall.

In my 2020 polytunnel, I noticed little difference in growth and need for water between plants whose roots were mulched with compost only, compared to those with miscanthus grass and seaweed on top of the compost mulch.

You also need to consider the succeeding vegetable plantings.

In the polytunnel, we transplant winter salads and leaf crops in October, within a few days of removing tomato plants.
If there was a mulch of undecomposed organic matter, we would need to remove this before planting salads. Otherwise, it would encourage slugs and would make leaf picking and cleaning more difficult, with bits of mulch sticking to the leaves.

Comparing the use of miscanthus and seaweed mulches around two rows of polytunnel tomatoes; this is mid-June, and subsequently I noticed little difference between them

Pantanu Romanesco with basil – removing lower leaves from tomato plants helps interplants, as well as making it easier to manage plants; we gave extra water for the basil

How much feed, or none at all?

There are many answers to this question, partly depending on what you want from your plants. For example, I am not used to growing with fertilisers and expect my plant leaves to carry a few imperfections, which some might call ‘deficiencies’. Tomato leaves are not always a lush and dark green colour.

Using feeds should increase the amount of harvest, but there are also risks of making plant growth more attractive to insects such as aphids. Also, you can reduce flavour, sweetness and trace element content of fruits.

Plus you need to consider how long the feeding will take you, the cost of any feed, and how you work out which feed is needed in what amount, and when.

Diagnosing a need for nutrients is difficult, even for professionals. See ‘Potential problems’ below for the example of blossom end rot, which many books advise is caused by a shortage of calcium. This is correct, however the shortage of calcium in plants (not soil) is itself caused by a lack of water, which means that plants cannot access the calcium that is present around their roots.
The simple remedy for blossom end rot is to water more, not to give calcium feed.

I suggest that as long as leaves look a reasonable colour and fruits are developing with some abundance, you do not need to feed plants growing in soil. However, plants in containers almost certainly will need feeding.

Organic feed

For this, as opposed to a proprietary feed of synthetic chemicals, I cannot give a precise formula or amount because organic feeds vary so much. To increase trace elements, I recommend some feeding with seaweed, or a scattering of basalt rock dust on the soil before planting. Or add dry seaweed with basalt rock dust to the compost in your container before planting.

A homemade option is to feed with a liquid from leaves of stinging nettles and comfrey. This is not smelly if you make it by stuffing any large bucket or pot as full as possible with the green leaves. There must be a small hole at the bottom to allow a resulting black liquid to drain into a container below – any bucket large enough to support the container or bucket above.
Dilute at approximately 20 to 1 when watering plants.

All sacks are filled with soil plus additions – on the left is rockdust plus seaweed, in the middle is bio charcoal and on the right is homemade compost; these Sungold tomatoes are showing strong differences by mid-June

I have given no feed to these greenhouse tomatoes – mid-September

Late September and these tomatoes have received no feed – Gigantonomo F1 in front, Feo de Rio Gordo behind with Black Russian

Sideshoot and leaf removal

Bush plants in the ground need no pruning or fruit thinning, except for weeding around and underneath – not a lot with no dig.

Cordon plants need sideshoots removed at least once a week, to always leave the one leading point at the top. Another small but regular job is to maintain support, either by twisting new growth around the string or tying the stems weekly to the cane.

For cordon tomatoes, not bush, it’s worthwhile but not obligatory to cut off all lower leaves as plants grow. Then you can access trusses for pruning and picking, you can see sideshoots more easily and under cover you have better ventilation. Some growers remove leaves to within 45 cm/18 in of the plant tops, and this works for them. I prefer more leaves than that.

Cut off leaves up to the height of either the lowest truss with fruits, or the one just above it.
The lowest and older leaves photosynthesise considerably less than new and young leaves at the top. This is why cutting older leaves causes little problem for plants.
Cut off finished trusses too.

1. Sideshooting a young plant – see where the shoots emerge

2. Remove all the new sideshoots but be careful when you are sideshooting at the top of the plant, because the main growing tip looks very like a sideshoot!

3. A plant after sideshooting only has one growing point

Truss length of cordon tomatoes

Every variety makes trusses of different lengths. Some are so long that if every flower is pollinated and grows fruit, it slows the ripening of other fruits on the plant and reduces the size of tomatoes.

For cherry tomatoes, I suggest an average of 10 to 15 fruit per truss will give you tomatoes of a nice size, ripening evenly. Cut off extra truss length to remove the extra fruit. Also cut the first and lowest truss to half-length or less, because the lowest tomatoes of long first trusses end up lying on the ground, plus they take energy from a still immature plant.

To grow beef tomatoes of the largest size and highest quality, cut off extra truss length once you see between two to four fruits per truss.

Stopping growth

This only applies to cordon tomatoes, not to bush plants. Unless pruned, cordon plants carry on making new stem until a frost arrives.

Before that happens we can concentrate the growth of late summer and autumn into fruiting, rather than futile new leaves and stems – the method is simple:

Pinch out the leading growth point approximately two months before your first frost date. At Homeacres this is during the second week of August.
Bush plants in pots can also be trimmed of new shoots from this time.
Continue to remove any sideshoots.

All growth energy now goes into swelling and then ripening tomatoes. Two months allows sufficient time for new trusses to grow their fruits and ripen most of them. There will also be a few green tomatoes when you clear plants in mid-autumn, should you wish to make sauces and condiments.

Sakura tomatoes and dwarf French marigolds – mid-September in the polytunnel

Pinching out tomato tops, outside in the Small Garden – 8th August 2018

‍

Harvest times and method

How to judge readiness

It’s your call at which stage to pick fruit. Anything from half coloured if you like them tart and firm, to fully coloured for softer and sweeter fruits. Leaving tomatoes on plants after they have reached full colour sees their texture become a little fragile, and there is less ‘bite’ to the flavour as the acid diminishes.

1. Options for ripening tomatoes – I have just picked these, slightly unripe when breaking

2. In the conservatory just two days later – we had already eaten the Honeycomb cherry tomatoes; this is 15th July when tomatoes are still scarce

21st July – lovely second truss on a compost-grown Sungold plant, outside in the sack with compost added to soil (see above), and with basil and trailing lobelia

How to pick

Handle tomatoes gently, bearing in mind that many varieties you grow have softer skins than ones you may buy. Lift a tomato upwards with your thumb on the calyx (the green, star-shaped stalk) to keep it attached to the tomato after it has been picked. They keep for longer when no skin is broken, which would happen if you detached the calyx.

In exceptional cases, you may have a whole truss with tomatoes all ripening at a similar time. You can then cut a whole truss, which is beautiful to behold and can be stored for a while.

Picking Big Boy F1 tomatoes, on 1st August in the greenhouse

Two weeks later, the greenhouse harvest peaks at 8.3 kg/18.3 lb of beef tomatoes and 3.7 kg /8.1 lb of aubergines, one week since the last pick

See the difference outside in the same year, with the Small Garden tomatoes on 30th August – Dorada and Sungold

When to pick and how often

In hot weather, from midsummer, picking can be every day for a few tomatoes, or twice weekly for plenty each time. Every time you go to pick some fruit you see other things that need doing, such as sideshooting, tying in, or perhaps extra watering. During high summer, and for best results, tomato plants need almost daily attention.

At some point you will experience a glut of more tomatoes then you can eat, or even give away perhaps. It is better to pick them when ready, instead of leaving them to go soft on the plants. The next step is to work on storage of this wonderful bounty.

Near season’s end for tomatoes on 25th September – harvests in the shed include basil and radicchio for the salad mix

7th October in a mild autumn, and tomato plants are still healthy – Sakura etc.

‍

Storing

By mid-autumn, there is as little sunlight as in late winter. Over many years I have compared the ripening of tomatoes in an unheated greenhouse or polytunnel, with tomatoes picked green* and stored in the house. The latter ripen well, and with little loss of flavour from having picked them early. Or, more correctly, there is little increase of flavour from leaving them on the plant.

We have a saying that on the 10th of October, the devil spits on the hedgerow blackberries. They no longer sweeten while changing colour, because the days are now too short and dark for much photosynthesis to happen, which is needed for plants to create sugars and the volatile compounds in ripe fruit. It is similar for tomatoes.

* By ‘picked green’, I mean fruits that are fully developed and showing perhaps a hint of colour. You cannot ripen undeveloped fruits, which need to grow more – they cannot do that once picked.

In your house, picked tomatoes keep better on the counter than in the fridge. 10–15 °C/50–59 °F is a good temperature for keeping tomatoes in nice condition, without them ripening too fast and with little loss of flavour. When in a fridge, the low temperature can slow down decomposition but may reduce sweetness and flavour. It’s not necessary to keep tomatoes in a fridge for long-term storage.

Unripe but fully grown tomatoes store for at least a month in ambient house warmth while slowly ripening. Trials suggest that ripening them out of sunlight, even in a drawer, is better than in full sun or next to a banana. Christmas tomatoes look the part, but have unremarkable taste and sweetness.

Cherry tomatoes can be frozen whole in polythene bags.
Tomatoes are excellent for canning/sterilising in glass jars in a water bath at near boiling temperature.

Dehydrating

At Homeacres I have an electric dehydrator and find that drying tomatoes is an excellent way to preserve flavour. Slice into 6 mm/0.25 in strips for dehydrating, over 12–18 hours at 50 °C/122 °F. Or use a slow oven, preferably with a fan and a half-open door. Sunlight in autumn is rarely strong enough to dry fruits.

The result is thin and dense fruit strips, highly aromatic, which store for over a year in jars.
During dehydration, they lose 95% of their weight.
Best results come from beef tomatoes because they have less moisture to start with.

1a. Early September, and after much slicing the dehydrator is crammed full of tomatoes, sliced to the same thickness so that they dry evenly

1b. After dehydration the tomatoes are really quite small and full of flavour

2a. 19th September with de Colmar tomatoes – six trusses to hang in the house, for eating as late as March; these have thick skins

2b. 2nd April – de Colmar tomatoes, seven months since they were picked; they have hung in a spare room of temperature 11–15 ° C, fifties °F

Saving seed

Be sure to save seed only from open-pollinated varieties, not hybrids. To check this out, I saved seed from one Sungold hybrid tomato and grew ten plants the following summer. Each plant grew differently, with quite large fruit of totally unremarkable flavour.

Tomatoes do not cross-pollinate. This allows us to save seeds from tomatoes of two different varieties, growing right next to each other.

If growing more than one plant of a variety, save seed from fruit growing on the plant that has the nicest growth habit and harvest.

Cut your tomato, as if preparing it to eat, and scoop out any seeds using a spoon.
Place seeds, and any tomato fruit sticking to them, in a cup with some water and leave them in the kitchen to ferment. This breaks down germination inhibitors on tomato seed, through fungal action.
After five to seven days you will probably notice a black mould of decaying fruit pulp on top of the water, which you can scoop off – the seeds are at the bottom, now much cleaner.
Give the seeds a rinse and then place, say, on cardboard, in a dry place for a few days. Then pop in an envelope or old seed packet, clearly labelled.
Tomato seeds store for up to ten years in any dry environment. Dry and ambient temperature is better than cold and damp.

1. Just in water, tomato seeds with a little flesh on are about to start fermenting – 12th August

2. Four days later, tomato seeds with four days of fungal growth

3. Removed from the jars and washed, the tomato seeds are now drying and are almost ready to put in paper envelopes

‍

Potential problems

Pests

Aphids are a common problem in spring. Their numbers build up quickly but should also diminish quickly when predators arrive.

When soil fertility is good, plant roots have sufficient moisture and transplanting was at the correct time, aphids may be present but should not cause any serious problem. By midsummer, the chances are you hardly notice them any more.

1. Greenfly/rose or peach aphid (Macrosiphum rosae)

There are several species and colours of greenfly, from yellow to light brown in colour. When they are numerous, you see leaf distortions as well as black mould on the undersides of leaves. The mould grows on the aphids’ honeydew excretions, which are enjoyed by ants.

Spay a moderate jet of water on aphids to displace them, for a while at least.

2. Greenhouse whitefly (Trialeurodes vaporariorum)

Their lifecycle is similar to that of greenfly. The greenhouse name comes from where they are most prevalent and noticeable. Susceptible plants include cucumbers and tomatoes, where one often sees them under cover.

Damage to plants happens from the tiny larval stage, when they are barely visible to our naked eyes.

Best avoidance is from not planting too early.
During late spring, allow the white- and greenfly populations to increase enough to feed predators, who arrive in early summer.
You can buy Encarsia formosa or lacewing larvae to reduce aphids, from early summer to early autumn. They are expensive and not worthwhile unless you have, say, ten plants or more, and expect significant damage.

Root knot nematodes (Meloidogyne hapla)

These can be common in soil used for growing vegetables over several years. They are most active in warm soils, 21–30 C/70–86 °F, and reduce root function, with knots visible on affected roots.

Growth will be stunted or below average. If you suffer this, and unless you can allow, say, two years between each summer of growing tomatoes, it’s worth buying plants on grafted roots. Some sellers also offer resistant varieties.

Tomato hornworm (Manduca quinquemaculata)

This is common in warmer climates, and the bright green caterpillars make significant holes in fruits in particular. The moths can be diverted by interplanting with umbellifers that flower, such as dill. Such plants, and marigolds too, attract insect predators of the caterpillars.

22nd June – aphids on tomato plants, which soon diminished as predators arrived; I had a healthy harvest from this plant

A result of the caterpillar damage to a tomato – the hole is quite large

Diseases

Late blight (Phytopthora infestans)

This is the main disease threat for tomatoes and potatoes. It arrives during summer, when night temperatures stay above 10 °C/50 °F for 48 hours, and air humidity is above 90% for all that time.

This results in enough warmth and moisture for growth of newly arriving blight spores, which become prevalent everywhere in such weather and blow around in the wind. Leaves quickly turn translucent brown, followed by dark spots appearing on stems and infection of tomato fruits or potato tubers.

In cooler and especially dry summers, blight is unlikely to be a problem.
It’s often ‘called wrong’, and blight warnings are issued by manufacturers of fungicide when there is no need to worry.

In temperate and damp climates, blight can be maddening for outdoor tomatoes, arriving just as they finally ripen in late summer. Salvage what you can, which may be little in damp weather.

If you spot blight damage on tomato leaves, best cut them off immediately – likewise for infected fruits and trusses. However, once the blight is in plant sap, enough to infect fruits and trusses, you may not harvest any more healthy fruit. Tomatoes may look normal when green, then start to brown and soften as they ripen. A further disappointment is that tomatoes ripened on blight infected plants do not taste sweet.

Dry leaves do not host blight spores, therefore water plants under cover at root level only. If you can keep leaves dry, all will be well, but it’s not possible for outdoor plants.
For outdoor tomatoes in cooler climates, grow early-ripening varieties such as Sungold F1, and cherry rather than beef tomatoes.
It is safe to put all blighted material onto compost heaps, because blight spores need living tissue to survive. Therefore they die as soon as decomposition happens, which occurs even in cool heaps, just more slowly than in hot ones.
For this reason, there is no need to change the soil in a greenhouse or polytunnel where blight infected tomatoes were growing, before planting tomatoes the following year.

12th August 2009 – after a wet summer there is leaf blight on this tomato plant in the tunnel

On the same day, also in the polytunnel and despite careful watering, this Jasper variety has stem blight

I put all blighted leaves, stems and tomatoes on my compost heap – no blight survives there, even at the cooler edges

Early blight (Alternarium solani)

Far less common, and less troublesome compared to late blight. I mention it as a possibility – growth would be weak, with spindly stems. Remove infected plants.

Other

Pyralid weedkiller

Horse manure and hay are at a small risk of contamination by aminopyralid weedkiller, occasionally sprayed on grass for making hay. Increasingly, however, it’s being used to control broadleaf weeds in other fields and verges.

It’s the most common weedkiller to persist in poisonous form and it’s lethal to potatoes, tomatoes and legumes, whose growing tips become curled and twisted.

I only heard of this weedkiller after suffering its effects in 2014, a year after I had added some horse manure to bulk up a heap of homemade compost. Potatoes, beans, lettuce, chard, alliums and cucurbits grew with deformed and stunted leaves, and matched the online photographs of damage.

Classic symptoms of hormone weedkiller are the growing tips curling and twisting; this is from aminopyralid in the horse manure that we spread on this bed of tomatoes

A growth test to check for pyralid presence – seeing if tomato roots in two-month-old manure grow healthily; this is a pass – a nice healthy plant

A deformed tomato from an allotment supplied with aminopyralid-containing cow manure in Ireland; the farmer will probably not have realised the danger of this poison

The poison has many points of entry to gardens, all invisible:

Horse manure from stables where horses have eaten hay sprayed with weedkillers such as Banish, Forefront, Grazon, Pharaoh and Runway. Or if horses were bedded on rape straw sprayed with Astrokerb.
Hay used by gardeners, as above.
Horse manure used in commercial bagged compost for mulching, which may even be called ‘organic’. The word organic on bags of compost means nothing if there is no symbol of certification.
Potting composts that have used contaminated horse manure or green waste composts. Readers sent photos of problems in 2020 from Bord na Mona compost, J Arthur Bowers and various Westland products. They were a minority, but you can’t tell if the poison is in a bag until your plants suffer, and it’s shocking when it affects your garden.

Pyralid problems have also occurred from the following:

Mushroom compost – this may be contaminated as it often contains horse manure.
Green waste compost, if some of the grass mowings were from lawns sprayed with weedkiller containing clopyralid, which affects growth similarly to aminopyralid. My local composting operation do trials of most, though not all, batches, using pea and red clover seeds. However, this is expensive because it adds time to their process.
Some cow manure.
Gardens and allotment sites close to fields sprayed with weedkillers containing aminopyralid weedkiller.

There is no straightforward remedy. In cases of mild contamination, the simplest is to wait for soil microbes to dissipate the poison, often within a year. Or, if you have spread a lot of contaminated material, best remove it, but to where?

We have been handed a difficult problem, and in 2021 a gardener who suffered this, Anna, set up a Twitter group where you can report damage. The hope is to find out how bad it is – if there is a high frequency of problems, we have grounds to push for the poison to be banned.

A problem compost in 2020 from Dalefoot – tomato deformity and growth almost stopped, yet this compost was certified organic by the Soil Association. I received little help from Dalefoot, who I guess could not afford to acknowledge that a powerful chemical poison was in one (not all) of their composts; other gardeners suffered similar problems. Dalefoot no longer add horse manure to their composts and I did not know that they ever did, because it was not written on the sack label

Jane Newrick’s pyralid-damaged tomato in Levingtons compost – 2019

‍

Leaf roll

Under cover tomatoes may suffer this if ventilation is inadequate. For example, the leaves roll in hot weather in my 12.8 m/42 ft long polytunnel, especially the leaves of cherry tomatoes plants, much less on beef tomato plants. I have no remedy except to wait for cooler weather. My polytunnel has doors at both ends but no side vents, because in winter I do not want too much cool breeze blowing in. The winter harvests are more valuable than the summer harvests.

Leaves rolling look as though the plants are short of water, but watering does not reduce leaf roll.
Ventilation of polytunnels from the doors at each end should be adequate, up to a length of about 9.5 m/30 ft.

After hot weather in late July, a healthy beefsteak tomato plant is next to the curling leaves on a Honeycomb cherry tomato plant

5th October – there is a good yield of tomatoes, despite leaf curl on these Sungella in the polytunnel

Compared to leaf roll inside, the outdoor tomatoes look healthy from reduced temperature extremes

Blossom end rot

As I explained above, this happens when plants cannot find sufficient moisture in the soil to carry nutrients to developing fruits. Give plenty of water as soon as you see any such rot, which shows as a small and jet black spot where the flower was. If the spot is a large area, this suggests the plant needed a lot more water than it could find.

Tomato mosaic virus

Viruses show as bright yellowing/curling/veining of leaves, and mottled fruits with light streaks and patches. They can affect celery, legumes, lettuce, cucurbits and solanums, plus many flowers.

This one is not common and I have never suffered it. If it does happen, best remove plants to the bin.

Verticillium and Fusarium wilt

Carried by a soil-borne fungus, whose spores can fill the veins of infected plants, to the point of preventing water and nutrient transmission. Lower leaves wilt and may turn yellow, then drop off.

The spores survive in most conditions, but can only multiply sufficiently to cause disease in warm moisture, with soil temperatures over about 30 °C/86 °F. Most vegetable gardeners will not suffer these wilts. I would suspect leaf roll first.

Other

Beef tomatoes sometimes lose their growing point and then cannot continue to grow normally until a sideshoot becomes the new leader. This delays growth a lot and is caused mostly by transplanting too early, when there is insufficient warmth for healthy growth. It’s worthwhile keeping a few plants in reserve after transplanting, for use as replacements if needed.
Irregular watering can cause skins to split. This only matters if you were hoping to store tomatoes for a long time. Otherwise it’s an indication of ripeness, because unripe fruit rarely split. Avoid split skins by watering consistently.
Spots on leaves are nothing to worry about – they are mostly on all leaves that are in the early stages of decay.

‍

And finally

Clear

Use a sharp trowel or knife to cut around surface roots, enabling plants to come free but leaving most of their roots in the ground. Cut stems to 10 cm/4 in lengths before adding to a compost heap.

It is safe to put any blighted material on the compost heap. Blight spores die once the plant tissue has decomposed, and even in cool heaps this will be before midwinter.

Follow with

Tomatoes grown outdoors finish by mid-autumn, which means there is little time for new plantings, especially after bush tomatoes.

However, cordon tomatoes give many possibilities. Options are to underplant or sow winter and spring vegetables, starting with spinach in late summer, then salads in early autumn and spring onions in mid-autumn.

Spread a little compost before undersowing or planting, because you may not find space to spread it in late autumn, between the new vegetables that are already growing.

Outdoor tomato plants on 7th October, with spinach that I sowed between them in early August; soon I cut around the tomato’s main roots to remove the plants – the spinach grew until May

October in the polytunnel and no frost, so I left a few tomatoes to finish ripening, with transplanted salads underneath for winter

16th October – with a Small Garden harvest; to the right behind me are tomato plants, with spring onions already growing underneath them

‍

Take the Quiz!