HOW TO GROW BRASSICAS FROM SEED

Vegetables for the Brassica family are not only amongst the easiest to grow, they can also provide a crop at almost any time of year. However there are few of us that would actually want to eat cabbages in the middle of summer so to get the best use out of your garden or allotment space it is better to grow brassicas for autumn and winter production. Not only will this leave a convenient ‘brassica free’ April-to-June gap, this three-month break will also helps to limit the incidence of common brassica pests such as whitefly.

For those who are unfamiliar with this brassicas, they are the edible stars of the spring and autumn garden. It is a comparatively large family containing a wide range of common leafy vegetables, such as cabbage, brussels sprouts, broccoli, kale and cauliflower. Root crops such as turnips, swedes and kohlrabi are also part of this nutritious group.

Growing Requirements

As a rule of thumb, brassicas are heavy feeders, preferring a well-drained soil rich in organic matter. They also prefer a site in partial shade with a soil pH between 6.0 to 7.5. To prepare the soil for planting, add a couple of inches of organic compost or well rotted manure to the ground and work it in - removing any large stones that turn up. Add lime - if necessary – to balance out the pH as your brassica crop can fail if the soil is too acidic. You can check the pH of your soil using an 'off the shelf' pH testing kit obtained from any good plant retailer. Once finished, tread over the soil to remove any air pockets, firming up the soil surface.

TIP. Autumn plantings of brassicas tend to do well following an earlier planting of peas or beans as these crops will naturally increase nitrogen levels with the soil.

Nearly all brassicas should be planted either directly into a seedbed, or singularly in modules under glass which can be transferred outside at a later date. When sown directly outside, the seeds should be sown relatively sparsely to reduce future thinning and the potential risk from pests. When lifting from modules try and keep the root ball as intact as possible to minimise any damage to the juvenile root system,

Broccoli, Brussels sprouts and cabbage seeds can be 'direct sown' outside when temperatures are as low as 4°C, but temperatures of 7°- 29°C will be more preferable for successful germination. Aim to sow brassica seeds in ½ inch deep in rows spaced 6in apart.


Cabbage and broccoli seedlings sown under protection will be ready for transplanting outside once they have reached between 3 -4 inches high. However, Brussels sprouts and kale should be about 6 inches in height before they go outside. Make sure that all protected seedlings are hardened off for at least a week or two before planting outside to make sure that they are tough enough to cope with ‘real’ weather conditions. Water the day before moving, and keep well watered once outside until they are established.

If you have them, space the plants according to their planting instructions which should automatically be printed with shop bought brassica seeds/baby plants. These distances can vary from 12 inches for small cabbages to 18 inches for Brussels sprouts. However, if you are without instructions keep to the safe side and thin all seedlings out to 18 inches apart.

Keep control of the weeds as they grow between your crop by hand weeding. Try and avoid using a how as this can disturb your crops roots and lead to the wind rock making the plants less productive

TIP. Avoid growing brassicas on the same piece of ground more often than one year in three, as this will help to avoid the buildup of soil pests and diseases.

TIP. Brassicas are a particular favourite of birds so use an appropriate and safe deterrent to stop them from picking off your seedlings. Brassicas are also susceptible to attack by the caterpillars of the cabbage white butterfly. Try covering crops with a crop protection mesh. It keeps the butterflies out, so they can't lay their eggs on the plants.

For related articles click onto the following links:
HOW TO GROW BRASSICAS FROM SEED
HOW TO GROW BROCCOLI FROM SEED
HOW TO GROW BRUSSELS SPROUTS FROM SEED
HOW TO GROW CABBAGE FROM SEED
HOW TO GROW CAULIFLOWERS FROM SEED
HOW TO GROW CELERY FROM SEED
HOW TO GROW CHINESE SPINACH FROM SEED HOW TO GROW KOHLRABI
HOW TO GROW SEA KALE
HOW TO GROW SPINACH FROM SEED
HOW TO GROW TURNIPS FROM SEED
WHAT IS SEA KALE - CRAMBE MARITIMA
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