This lesson has a grouping of vegetables that are mostly eaten as salad ingredients and grow rapidly. None of them grows in summer, and they are from a selection of plant families.
Other salads such as Oriental leaves, plus rocket and lettuce, are in Lesson 13 (Course 3A) and Lesson 20 respectively. I include some photos of them here for comparison purposes, to show their larger leaves and faster regrowth. They are less hardy to frost than the three featured here.
Three hardy winter salads
1. Claytonia (Claytonia perfoliata) is in the Montiaceae family of flowering plants, native to the Americas, in particular to mountainous regions with moist conditions.
Its colloquial name is winter purslane, but it’s not in the Portulaceae/Purslane family.
It’s also called miners lettuce, from its popularity with miners from two very different locations – it was eaten during the 1849 Californian Gold Rush and by tin miners in Cornwall, UK, who (it is said) picked some from the hedgerows to pop in their pasties, before descending.
2. Corn salad (Valerianella locusta) is native to and wild in much of northern Europe and Africa, then was taken to North America and has escaped to grow wild there. Its German name of ‘Feldsalat’ (field salad) reflects how it grows like a weed in disturbed soil, and the English name ‘corn salad’ likewise originates from it growing after harvests of wheat and barley. Other colloquial names are ‘mâche’ and ‘lambs lettuce’.
3. Land cress (Barbara verna) is in the Brassica family, with a pungent mustard flavour very similar to watercress. It’s native to southern Europe and mountainous regions in general, including the Appalachians where it now grows wild. Other names include ‘American land cress’ and ‘upland cress’. It grows in damp soil and is healthiest in the cool of winter.
- Days from seed to first harvest: Claytonia – 50, corn salad – 60, land cress – 70
Seeds sownLeaves ready to harvestLate summerMid-autumn, mostly before winterEarly autumnLate autumn through winter
- Best climate is temperate, moist, cool more than hot, can be frosty in winter.
Why grow them
A special attribute of these plants is their hardiness to cold, combined with an extraordinary ability to make new growth in conditions when many other plants do not! They give green leaves through winter when fresh greens are so valuable for our health.
Flavour-wise they are very different. Land cress is pungent, corn salad is nutty and with a waxy leaf, while Claytonia is succulent with soft leaves and not a huge flavour. Corn salad has three times more vitamin C than lettuce.
Pattern of growth
These are not plants I would attempt to sow in spring for harvesting late spring and summer. They are likely to flower, suffer more pests and grow less healthy leaves – mildew on corn salad that you sow before early autumn, for example.
These plants need regular moisture to keep growing, yet mostly have surface roots. This is partly why it is difficult to grow them in summer, because when the surface dries they suffer, from being unable to root deeply for moisture.
The natural season of leaf growth is autumn through winter, from germination in late summer to early autumn. How much they actually grow in winter depends on the weather. They all survive hard frost, colder than -10° C/14° F, but won’t grow in those temperatures. See the work of Pam Dawling in Virginia USA, who has researched the lowest temperatures for vegetable survival.
Flowering time is early spring and you can easily save seeds then, when you have a few plants growing together to ensure cross-pollination.
Suitable for containers/shade?
These plants are fine for both shade and containers. Their shallow rooting system means that growth is excellent in any kind of box, tray or pot that is not too deep.
The trays I use for winter salad are 10 cm/4 in deep, filled with multipurpose potting or container compost, packed in firmly. Although these plants are not heavy feeders, they crop for several months. To save any need for feeding, it’s good to use compost with sufficient nutrients, such as potting compost.
I compared growth when using different composts, starting in October 2020 with winter salads in four trays, two of which contained commercial compost and two my own compost. Some rocket, mustard and coriander died in my own compost, I think from wet and soggy roots. This shows that when using your own compost in containers, it benefits from a drainage improver such as vermiculite or perlite, about 20%. I shall do that next time!
Salad plants in the photos below are not the only ones of this lesson, but they grow and harvest with the same timings.
- Sow in September.
- Transplant into boxes or the ground in October.
- Harvest through winter, according to the ambient, under cover temperature which regulates growth.
- Continue picking leaves until flowering initiates in early to mid-spring.
Claytonia and land cress have not been selected into named varieties. Corn salad is more important commercially and has been bred to produce varieties with attributes like colour and plant size.
You can sow direct or in trays.
Sowing direct is difficult when the soil is often dry and beds are full of vegetables still growing. Therefore raising plants in trays is worthwhile, also for reduced pest damage to seedlings.
- Seeds germinate in about one week.
The absolute best time is early autumn, to avoid early flowering and disease, and for precious harvests in winter months. Below are my best sowing dates for growing outside here, to give you a reference. You can sow a week later, for growing through winter under cover.
- Claytonia – mid-September.
- Corn salad – 5th–15th September, a week earlier in Zone 7, for example.
- Land cress – mid-August for autumn harvests outside, early September for winter cropping.
I suggest one plant per cell, for ease of harvest and larger leaves. Water trays to capacity before sowing.
Sow two or three seeds per cell, or a pinch of tiny Claytonia seeds (later you thin to the strongest).
Cover seeds with almost no compost, then water lightly.
For direct sowing, follow this method.
- Often you need to run water along the bottom of a drill, before dropping in the seeds. In early autumn it’s common that the surface is dry.
- Make drills 22 cm/9 in apart, even a little closer if it’s possible.
- When direct-sown seedlings have two true leaves, thin to the spacings described below.
Transplant size and time
Growth slows by early October so these may be four weeks old before you transplant. Or, if the ground is ready, you can pop them in as small seedlings after two to three weeks. There is no absolute correct size.
It’s rapid to make holes with a wooden dibber, then pop in the small module seedlings. Plant a little deep but not too much so, especially for corn salad which has no long stem.
Corn salad never grows large and can be as close as 10 cm/4 in. Claytonia and land cress grow larger, and 22 cm/9 in allows for many healthy green leaves which are easier to pick. The 22 cm/9 in spacing allows a longer root run, which helps plants to grow all winter for many pickings.
There are many possibilities, as you see in the photos just below and dotted through this lesson. The principle is to find space between vegetables that will soon finish. During autumn this can mean a lot of possibilities, as long as the pattern of leaf growth on existing vegetables allows sufficient space for new leaves.
Suitable vegetables to transplant between are lettuce, Florence fennel, swede, winter radish and endive.
See how the outdoor salads are coming good after winter
You almost never need to water any of these plants. However, do give water to transplants and if it’s dry in mid-autumn, it’s worth watering corn salad in particular.
These plants all root shallowly and do not tolerate the surface being dry, so they also benefit from a little water in early spring, if the soil is drying quickly.
How to judge readiness
Claytonia grows up and outward into a mound of leaves on quite long stems, including a few male flowers. Take a first cut before you see more than one or two male flowers, and before too many of the first leaves start to discolour with age.
Corn salad grows a tight and only medium-sized rosette of central leaves, which then stop growing larger because new growth is now on side shoots around the central rosette. First harvest is to cut the centre leaves, once you notice sideshoots developing. Cut low enough to secure the whole rosette of middle leaves, but not too low, so that at least a few sideshoots remain to continue growing.
Land cress also grows sideshoots, so look for outer leaves large enough to twist off before there are too many sideshoots.
How to pick
Claytonia and corn salad need to be cut, while land cress can be cut or picked. Cut as low as you can without damaging the central and smallest leaves. Cutting low is good, to reduce the amount of yellowing stem in the way of subsequent harvests. Just be sure to cut higher than the smallest new leaves, otherwise regrowth may not happen!
When to pick and how often
After cutting across plants, the next harvest will be after four to eight weeks, according to how cold winter is. With corn salad, the new harvest is small sideshoots, nobody’s favourite job in cold conditions, whereas the other two are fantastic for repeat cropping. By early spring, there is a much shorter time interval between harvests, which are larger.
In the cool of winter, these leaves keep for at least a week, even outdoors, in the garage for example, and preferably in a polythene bag. It is more practical to harvest quite a few in one go, than to keep popping out in winter weather!
The period of cropping continues right up to the flowering stage, in mid-spring. Next, within four weeks, there are viable seeds on Claytonia, around six weeks for corn salad and up to ten weeks for land cress.
Gather flowering stems as soon as you notice some dry seeds on them, which means before too many seeds fall onto the ground. With land cress, twist out whole plants and hang to dry until midsummer.
Slugs and snails
They are prevalent in winter’s moisture, but less active in the cooler conditions. I often find slugs while harvesting leaves of these plants but do not see a lot of damage, because they are not slugs’ favourites.
These are ways to reduce slug numbers:
- Adopt a no dig approach, which allows slug predators such as beetles to maintain or increase their numbers. Ground beetles (Carabidae) can eat a lot of slug eggs and baby slugs.
- No dig results in soil with good aeration, compared to thin layers of damaged and compacted/anaerobic soil after digging. Fermentation can occur in anaerobic conditions and results in alcohol, which attracts slugs.
- Remove and reduce nearby slug habitat.
You can protect susceptible plants using bird netting, However, in winter it’s more efficient to use mesh, for extra weather protection. In my garden, I have not known rabbits to dig under mesh or fleece, but others have experienced this.
These will eat land cress, in cold winter weather above all. Bird netting is a good remedy – support it on hoops so it’s held more than 30 cm/12 in above plants.
The main one is mildew on corn salad, but only when it is sown too early and therefore growing in dry conditions in early autumn.
- These plants are rustic, can grow in the wild and suffer very few problems.
Either cut the main stems at ground level, or twist out plants to leave most roots in the soil. It’s good to spread some compost in spring, between finishing the winter salads and transplanting summer vegetables.
A cover or mulch of 2.5 cm/1 in of compost will set your soil up nicely for cropping through the whole year.
Under cover, we add 4 cm/1.5 in, because of the intensity of cropping during every month of the year, with both summer and winter vegetables.
These plants are efficient at growing in space that would otherwise be unused in winter. Then they finish in spring, in time for any subsequent planting.
There are few implications related to rotation, and only land cress is related to commonly grown vegetables. You could still follow it with, say, cabbage, if that’s what you want to grow in that bed. It’s a free choice.
For the fourth salad, see the endive guide.