Brassicas are healthy and versatile, the perfect crop for harvesting during autumn and winter. They include many common leafy vegetables including cabbage, sprouts, broccoli, cauliflower and kale. The genus also includes root vegetables such as swedes, turnips and kohlrabi. Brassicas are nutritious and easy to grow. If you’re just starting out growing your own veg, we recommend sprouts and cabbage as Brassica starting points.
When and Where
Brassicas should be planted out in the early spring. They will thrive in the partial shade, in free-draining, fertile soil. Stones should be removed and the soil made firm – you can get rid of air pockets by treading on the soil. Lime the soil if it is acidic, as a pH of around 6.5 to 7.5 is ideal. Compost or well-rotted manure should be worked in as the best preparation.
How to Plant
If you are planting out seedlings or plug plants, water the root ball if necessary and leave to drain for 24 hours in a shaded place. Then plant out in final growing positions in your garden pots, greenhouse or a sheltered, warm location. Ensure that the plants are well fed and watered.
If growing from seed, sow these in a seedbed or in modules, 1.25 cm deep. Once germinated, thin out to between 6 and 8 cm between plants. Broccoli and cabbage seedlings can be transplanted when they reach between 7 and 9 cm high, while Brussels sprouts and kale are ready for transplanting at around 15 cm. Water the plants before re-potting and keep well watered until the plants are newly established. Spacing for plants varies across different Brassicas from small cabbages to Brussels sprouts.
Summer varieties of cauliflower, green broccoli and cabbage will be ripe for harvesting from mid-July onwards. For broccoli, cut the flower shoots when well-formed but before the flower buds open – the shoots turn tasteless and stringy once in flower. For cabbages, take out the entire plant in order to reduce the risk of clubroot, a Brassica fungal disease. For other Brassica crops, use a sharp knife to cut close to the ground. Autumn and winter varieties are harvested from mid-October onwards, including winter and spring cabbage, early and late varieties of broccoli, kale, Brussels sprouts, swede and turnips. For sprouts, begin harvesting with a sharp knife when the sprouts at the bottom end of the stem are tightly closed and nut-sized. Only pick a handful of sprouts from a stem on any one day. Opened, unfurled sprouts and yellow leaves should be pruned away.
For kale, harvest from mid-November on, removing young leaves from the plant’s crown. As you strip the crown, side shoots will grow which in turn should be ready for harvesting in the early spring. Only pick out a few leaves at a time.
Through the Year
A range of diseases and pests can afflict Brassicas. Chief among these is club root – leaves will yellow out and the roots swell, becoming stubby and possibly rotten; the plant’s growth will stunt. An infected plant should be uprooted and destroyed. To avoid the build-up of soil pests and diseases, rotate your crops so that you only grow Brassicas one year out of three.
You’ll need to deter birds away from your Brassicas, particularly when the plants are small – experiment with netting, bottle tops or a string of CDs. A net or mesh will also be useful for keeping cabbage white butterflies away from your plants where they will lay their eggs – leaving your Brassicas as food for the caterpillars.