Fothergill's Growing Guide: Kale

Average time to harvest

24 weeks

Sowing depth

1.5cm

Soil type

Well cultivated, fertile soil

Kale is about as easy going as a vegetable can get. If the soil drains well and it gets plenty of sun, it really isn’t too picky about its growing conditions compared to other members of the brassica family.

That’s why it’s one of the best vegetables to start with if you’re new to gardening: it’s easy to grow and care for, productive and reliable, and there are lots of varieties to choose from.

Want to find out how to grow your own kale from seed? Keep reading and we’ll tell you everything you need to know.

Did you know?

Its botanical name is Brassica oleracea Acephala.

Kale, also known as borecole, is normally grown as a cut-and-come-again crop, picking just the required amount of leaves and allowing the plants to grow on. This way kale can be harvested for much of the year. Low-maintenance compared to other brassicas, it’s the ideal hardy winter crop. In fact, a winter frost improves its taste by turning the starches to sugars.

Once referred to as ‘peasant’s cabbage’, it is one of the earliest known
European vegetables.

Kale is full of antioxidants and nutrients, and is particularly high in vitamins A and K, a calcium and iron.

There are green, purple, red and white varieties, as well as curly leafed, plain leafed.

Growing at a glance

Kale will grow in almost all conditions but benefits from soil enriched with fresh compost or well-rotted manure.

Sow from March onwards into seed trays or modules, or outside into a well-prepared seed bed or final growing position.

Keep the area weed free, and don’t let the soil dry out.

Apply a nitrogen feed as the plants mature and grow.

Kale leaves can be harvested at any stage, from when they’re young to mature, for a continual winter crop.

Sowing seed

Kale can be sown indoors from March to May. Using a seed tray, fill with a seed compost. Tamp the soil down to create a firm surface, water the compost, then sow the seeds thinly on top and cover over with a thin layer of compost. Keep moist and warm, a temperature of approximately 15°C is ideal. Once they’ve germinated, give them plenty of light so they don’t become leggy.

Direct sowing into the final growing area can be done when the soil is warmer and more workable, from March to May, or until September for crops of baby leaves.

Prepare the open growing area by adding plenty of organic matter and working it into the soil. Firm the soil down with the back of a rake, or use your heels to walk over the growing area, and then create a fine, level tilth. Water the area before sowing to avoid dispersing the seed.

Create drills 1cm deep and 15cm apart for baby leaves. For mature plants, rows should be 45cms apart, if sowing directly. Sow seed thinly, then cover over with fine soil. Seedlings usually appear in 14-28 days. If sowing early in the growing season or if pigeons are a problem, a cloche or horticultural fleece may be needed to protect the sown area.

Pricking out

For plants directly sown into the final growing area, thin seedlings to 45cms apart.

To avoid disturbing the roots, either pinch-out the weaker seedling or cut it away. Keep soil moist.

Hints and tips

Harvest the young and tender leaves for salads.
Only harvest what you need as kale keeps best on the plant.
As long as you continue to harvest, the plant will continue to grow and produce new leaves.
If short on space, try growing kale amongst flowers; the foliage makes it an attractive ornamental. Kale can also be grown in large pots and containers.

Growing on

When indoor seedlings are 10-15cm high, they are ready to be planted out into their final growing positions. Before planting out, let them harden off outside for a week beforehand by bringing your plants outside for a few hours every day so they can acclimatise to outside conditions.

For best results, the growing area should be prepared with plenty of organic matter worked into the soil, adding a general-purpose fertiliser, if necessary. Firm the growing area down with the back of a rake, or use your heels to walk over the growing area, and then create a fine, level tilth. Plant deeply, up to its first set of leaves, and firm around the roots. This will help them establish a good root system and prevent wind rock. Plants should be spaced 45cms apart in rows 45cms apart. Water in well. This also applies to plants that were grown and transplanted from a seed bed.

Plant maintenance

As plants mature, mound up around the base of the plants to help support them. Taller varieties may need staking.

Water regularly, keeping the soil moist and the area weed free. Provide a plant feed as plants begin to mature, and remove any yellowing leaves.

Kale leaves can be harvested when they’re young or left to grow on for a winter crop. Either twist the leaves down and away from the main stem, or use a knife to cut the leaves off.

Jargon busting

Organic Matter

Broken down plant matter, leaf mould, manure and compost.

Seed Tray

Used to sow seeds. Once seedlings appear, often pricked out and moved on.

Germination

When seed begins to grow and its first shoot appears.

Propagator

A covered, typically heated container filled with compost, used for raising seeds.

Tilth

Surface soil which is fine and crumbly.

Drill

A shallow trench in the soil, for seeds to be sown in.

Pricking Out

Removing seedlings from growing trays and planting them individually to grow on.

Thinning

Removing seedlings that are growing too close together to allow the remaining crop to grow on successfully.

Common problems

Mealy cabbage aphid

A grey white fly found as a cluster under the leaves of kale. They suck the sap of the plant, causing the leaves to discolour and become distorted. Check plants regularly, and if discovered, remove by hand or gently hose the infestation off. Pest control sprays can also be used.

Slugs and snails

A prolonged period of wet weather can encourage slugs and snails to attack the plants. Pick them off by hand, or set up beer-traps to deter them.

While kale isn't quite as vulnerable as other brassicas, it can still be affected by problems such as:

Birds and caterpillars will happily eat the leaves of the plants, so place fine netting over the crop at the time of planting. This will also deter the white cabbage butterfly from landing on the plants to lay its eggs during the summer months; an infestation of caterpillars can quickly devastate a crop.

Cabbage root fly larvae feed on brassica roots. When planting into its final growing position, place a brassica collar around its stem, just above the soil. This will help prevent cabbage root fly from laying eggs at the base of the plant, and its hatched larvae from eating and destroying the roots.

Club root is a fungal infection that damages the roots, leaving them swollen, distorted and stunted. The foliage can also discolour. If plants are infected, remove from site and destroy. Wash hands, tools and boots to help prevent the spread of infection. Avoid planting brassicas in areas where club root has occurred. Buy seed varieties that have some degree of club root resistance.

Ready to get planting?

Which variety of kale will you bring into your garden? Have a look at our range of kale seeds and find out first hand just how rewarding this hardworking brassica can be.