Pastinaca sativa, family Apiaceae
Many vegetables are in the same family as parsnips. In this course we have carrots, celery, celeriac and fennel, and others include parsley, coriander, dill and cumin. All grow umbel shaped flowers in their second summer, hence the colloquial family name of umbellifers.
Parsnips are native to Asia and Europe, and were much appreciated by the Romans. They are nothing like as popular as carrots and deserve to be better known, partly because they are easy to grow and are a substantial harvest for winter.
- The part we eat of both parsnips and carrots is the taproot.
- They are the two vegetables that are best sown direct rather than transplanted. Transplants usually suffer damage to the taproot, resulting in a smaller harvest with fanged roots.
Wild parsnips are common in hedgerows of temperate regions, and they carry tall stems with pretty white flowers, every year in late spring. All parsnips are biennial plants that we grow as annuals – see ‘Varieties’ below.
- Days from seed to first harvest: 180, to last harvest: 390
Parsnip seeds sownParsnips ready to harvestEarly springAutumn through winterLate spring to early summerLate autumn through winter
- Best climate is moist, warm summers, not too hot and dry, with cool winters.
Why grow them
Parsnips have about an 80% water content, which may sound a lot but is very much at the low end for vegetables. Carrots are 86–95% water, depending on the variety and when harvested.
About 5% of parsnip roots is sugar of different kinds, which helps them to resist damage by freezing. In cold weather the sugars convert from starch to sucrose, hence the advice to eat parsnips after a frost, for more sweetness.
- They were used as a sweetener in parts of Europe, before the arrival of cane sugar in the 18th century.
The sweetness is also enhanced by roasting, which, in the UK at least, is a traditional way to eat parsnips and makes them super tasty. They are also delicious grated raw in salads, with some lemon juice.
The photo above right is of harvests in 2016 from my Three Strip Trial – I am unsure why Strip 3 was lower in that instance.
Pattern of growth
One difference to carrots is that parsnips continue to swell all through the growing season, from one early sowing. In contrast, carrots start to lose quality about four months from sowing, becoming less tender and sometimes splitting.
Through autumn, parsnip leaves start to yellow and then go brown, leaving what was a bed full of abundant growth looking suddenly barren. Our food, the parsnip taproots, survive winter in a dormant state. Then, as soon as there is warmth in late winter or early spring, they sprout again.
- New growth in the second spring is not contributing to any more growth of the parsnip tap root.
- In contrast, it is taking goodness from that root, because parsnips are storage organs that power new growth in early spring to make flowers and eventually seeds.
Growing a flower stem makes the taproot woody and inedible. Therefore it’s best to harvest parsnips by late winter before too much growth has happened. From early spring, sugars in the roots are used by new growth, while the texture becomes fibrous.
Suitable for containers/shade?
Parsnips will grow in shade, and you could grow them in a container as well, although they would occupy the container for a whole year.
You need a pot of 30 cm/12 in depth, or a little more, in order to have a worthwhile harvest.
Varietal ups and downs
All open-pollinated varieties have the caveat of how well they are being maintained. The word variety also means discrepancy! The correct botanical term is ‘cultivar’, but I say variety because almost everybody then knows what I mean.
A cultivar/variety of parsnip called The Student was bred by Professor James Buckman from 1847 to 1861. It was a project to show his students how one can selectively breed from wild stock. The result was even more successful than he had anticipated.
They started with wild parsnips from the Cotswold hedgerows near Cirencester. First they collected seeds, then the next spring sowed these to grow ‘wild’ parsnips. From the harvests that autumn, they selected the growth characteristics they wanted. They replanted those parsnips the following spring.
- Within five years, they had an acceptable parsnip – reasonably tender and fleshy, and of good flavour.
- Within 14 years they had a named variety, reckoned to be among the best available for gardeners.
The other side of this trial shows how the characteristics we prize can quickly be lost, as well as gained. Seed producers need to be careful with their root selections every year.
White Gem has medium length roots, broad shoulders and a little resistance to canker.
Tender and True is acclaimed for flavour. I like it but feel that any flavour difference is not huge.
The Student, worth a try!! The outcome will depend on who looked after it.
Gladiator F1 is, in my experience, the most canker resistant variety, with roots of even shape and often long.
Javelin F1 grows slightly thinner roots than Gladiator, also with resistance to canker.
Hamburg Root grows leaves like parsley and a root like parsnip, although smaller if you pick the parsley a lot. Fun to try at least!
It was, and perhaps still is claimed that parsnips need super loose soil in order to grow successful tap roots. I used to read descriptions of how you use a crowbar in clay soil to make a hole, fill it with sand and sow the parsnips in the middle of that hole. Please don’t do that!
The photos below illustrate how I grow parsnips in heavy clay soil, and many others also do this all the time. It’s totally unnecessary to loosen soil in any way before sowing parsnips, which grow into dense and undisturbed soil even better than carrots do. The parsnip tap root takes a lot of discouragement before possibly failing to descend.
Seeds germinate in 15–21 days. They are famously slow and need moisture around them for at least the first 10–14 days. Then the taproot descends to find moisture below. Their slow germination causes anxiety.
It’s possible to sow in late autumn and for seeds to germinate in the spring, after surviving all winter in the cold soil. This is how it happens in nature, where seeds fall out in late summer to autumn, then spring to life after winter. It helps if your soil grows few weeds and you don’t dig!
- I sowed seeds in November, for a photoshoot and not for a crop, then I forgot the seeds were there until March. They all grew!
- Best results in the garden are from sowing late winter to early spring.
- My favourite time here is the spring equinox, but you can also sow right up until early summer.
It’s less about timing and more about having moisture present for germinating seeds, during an uninterrupted two weeks or so of germination. This is more likely in early spring than in late spring, for example.
Prior to sowing, rake the surface level and break up any larger lumps of compost. This gives every seed a chance of being at the best depth – not too deep but in contact with moist material.
With no dig beds, you are sowing into the compost that you spread on top last autumn or winter.
Sometimes it’s claimed that compost on or in the soil for growing parsnips makes them fork. This is an outdated statement, which assumes compost is dug in. It’s probably untrue anyway, from what I see of the parsnips we grow in the dig bed of my trial.
- Drills can be 5 cm/2 in from the top of their ridge to the bottom of the furrow, so that after sowing and then filling them in, parsnip seeds are 2.5 cm/1 in below surface level.
- The drills in surface compost have moist compost at the bottom, which holds water nicely while seeds are germinating.
- If that compost looks dry, it’s worth running water along it, just in the bottom of the drill, before sowing seeds.
It’s rare that weeds are a problem in no dig. However, because parsnips germinate so slowly and we sometimes sow them so early, just when the spring’s main flush of weed seeds also are germinating, the two can coincide.
A sowing of parsnips may be lost in the growth of new weed seedlings. Radish can rescue this situation.
Radish seeds germinate rapidly and show you the sowing rows, which makes it easier to weed between them. Early spring is radish roots’ natural season of growth, before flowering in late spring – see Lesson 28.
- Sow a radish seed every 5 cm/2 in.
- Harvest the radish within six to eight weeks, with a gentle twist – I have never seen this damage the parsnip seedlings. The radish are a ‘free’ and extra harvest.
- A cover of fleece over the newly sown bed will keep insects off radish leaves, as well as providing warmth for germination of both radish and parsnip.
The main factor is seed freshness. Parsnip seeds decrease in germination percentage with each succeeding year, and quite quickly.
I sowed two batches of seed in the beds shown in the photos above and below.
- In rows one and three, counting from the left, it was seed I had bought two years earlier.
- In rows two and four, it was seed that I had bought one year earlier.
I was actually impressed by the germination rate of the one-year-old seed, but lost harvests from sowing seed I had purchased two years earlier, showing that it’s not worth hanging onto seed beyond one year from when you buy it. Also, you don’t know its age at the time of purchase, and this varies.
An investment in buying new seed every year is repaid by the amount you will harvest. The growth failure I experienced in rows one and three, even though I resowed in early May, was a loss of three-quarters of my potential harvest from those rows.
- For this sowing I trialled a cover of cotton muslin, to see how well it worked compared to normal polypropylene fleece. It worked as a cover to retain warmth and keep off pests, but is expensive. It costs five times more than normal fleece and degrades more quickly. I am not yet sure if we can use it for more than one extra year, compared to at least four years’ use from a fleece cover.
It is possible to transplant parsnips for a successful harvest. But it is not easy, and the likely outcome is a short, hopefully fat parsnip with many fanged roots coming from it.
The parsnips you see below right are the best result I saw to date. The photo was sent to me by a clearly very capable gardener!
The rows you create can be 30–35 cm/12–14 in apart. Either along or across the bed is fine, that is entirely your choice. In the rows, sow a seed every centimetre or so.
However, parsnip seeds are light and it’s often windy when you are sowing. It’s rare to achieve great precision, but you have the chance to correct that when you thin seedlings, six to eight weeks later.
After a slow start to life, parsnips grow large leaves that feed into potentially large roots. Sowing seeds more closely still makes sense, because if you sowed seed at a final spacing of, say, 10 cm/4 in, that would likely result in gaps, because small seeds benefit from having neighbours that are also germinating. The radish help too.
Parsnips are the vegetable that I water the least. There are two reasons for this.
- They grow slowly through a whole year and have plenty of time to catch up later, if the soil is sometimes dry enough to restrict growth.
- The long taproot is excellent at foraging for water.
If you want the highest harvest, give some water in late summer to early autumn, if rain is lacking.
How to judge readiness
This is your call, depending on when you want a first harvest and how big you want parsnips to be. Any time from early autumn, harvest one or two to see how they are and how they taste.
The main period of harvest is winter. Parsnips are a classic winter vegetable, when they taste good and stand so well in the ground, for harvesting any time you like.
How to pick
This depends partly on your soil. If it’s heavy clay, you may need a spade: push it in almost vertically and close to the parsnips. Often you are levering out two or three at once.
Insert the spade almost to full length, say 20 cm/8 in, and pull the spade handle towards you in order to gently lift the parsnips, while you also pull them upwards with your fingers around the shoulders.
When you can ease them upwards gently, there is a fair chance that you will extract them together with the fine and very long taproot. I love it when this happens because it’s such a great example of soil openness and quality.
- For no dig, this is a disruptive harvest, because it breaks the soil structure to some extent. My preference, after using a spade, is to push the soil back down with my foot, not too firmly because it is often wet.
- An option for lighter soils is to put your hands around the shoulder of a parsnip to harvest, push it down firmly and then pull upwards. There is something about the downward push which makes the pull more successful.
Parsnips store in the soil, but there are two possible disadvantages:
- In heavy soils, the shoulders may rot with canker.
- Animals such as rats and rabbits may nibble the shoulders through winter.
You could harvest all parsnips in early winter and store them in boxes, crates or paper sacks – best leave with the soil on so they stay moist.
Towards the end of winter, you will see bright green stems and leaves sprouting from parsnips, according to how mild the winter has been. Best harvest parsnips before leaves are 15 cm/6 in long, by early spring. Sweetness diminishes as leaf growth increases, and parsnips grow more fibrous.
This is possible and a long-term project. Seeds ripen in the second summer, from parsnips you transplanted or left in the ground.
Select your finest parsnips, about six – they can be planted or left in the ground close together. Close spacing, say 10 cm/4 in apart, makes it easier to stake and tie the stems. Seeds start to ripen around midsummer, and you must pick the umbels before they start to fall. Check for them going brown.
Professor Buckman’s parsnip The Student shows how much you can influence eventual growth from your homesaved seeds, by careful selection of which parsnips to grow for seed.
Which pests are likely, and when
Carrot root fly is the main pest, damaging the outer skin, but proportionately less than on carrots thanks to parsnips’ broader diameter, meaning less skin compared to middle. Also, the high dry matter content slows down eating by root fly maggots.
Other pests are not significant, unless your ground suffers voles and rodents. During my first summer at Homeacres, I found that putting mousetraps with peanut butter under large leaves, near to where damage had happened, caught two voles in three days.
Canker disease (Streptomyces scabies)
This is the main one!
It’s a common disease of parsnips, especially in soils that lie wet. It is caused by two or three different fungi, and may be brown-orange or purple-black in colour.
Some varieties are less susceptible – Gladiator F1 suffers the least in my experience. Even when looking bad, damage may be shallow, and underneath the brown slime there is still good parsnip to eat.
The RHS website advises that parsnip canker is caused by any of summer drought, winter rains, over-rich soil or damage to the crown, showing how it’s hard to manage disease! Canker may also be increased by early sowing, and carrot root fly damage from the hatching of late spring.
Possible remedies therefore include:
- Extra compost on heavy soils, to raise the surface level and keep it drier.
- Sowing as late as in the first week of summer.
- Covering early sowings with mesh from mid to late spring.
- Sowing the most canker-resistant variety you can find.
Remove any large pieces of fruit or stem, rake level and spread 2.5 cm/1 in of compost. Leave over winter, ready for next steps in the spring.
Parsnip harvests finish too late for any new sowings until spring.
Any vegetables can follow them, preferably of a different family. I reckon leaving at least a year between growing carrots and parsnips in the same ground, especially parsnips, because they occupy a bed for all or most of the growing season.