As we attempt the first of the group of veg loosely called brassicas we immediately hit a problem with naming. Brassicas are a large group of plants, all in the Brassicaceae, once the Cruciferae, which have four-petalled flowers – hence the crucifix reference. Most of the veg belong to the species Brassica oleracea (oleracea means vegetable) which is European and has been cultivated and selected and bred for so long that it has been transformed from a scruffy coastal weed into cabbages, cauliflower, kale, sprouts, collards, Kohl rabi and broccoli. Other brassica species have given us turnips, swede and all the Oriental veg. Other ‘brassicas’ – related genera – include honesty, stocks and wallflowers.
Because they are so closely related, they all have rather similar requirements. They need well-drained soil, though they cope well with heavy clay soils and they prefer an alkaline soil, thriving on chalky soils. In fact, one of their biggest problems, clubroot (below), a fungal disease, is worse in acid soils and by adding lime you can reduce the severity of the disease.
But back to broccoli. Sprouting broccoli is a spring crop, harvested from early March to April. The leafy flowering sprouts are either purple or white. Basically they are multi-headed cauliflowers and quite easy to grow. I have always regarded them as princes among veg and look forward to the tasty sprouts in spring. But there are problems. The biggest is that they are in the ground for a long time. Seed is usually sown in May and they are planted out in June or July and they take up a lot of space in the plot until the following April. They are bulky plants and need to be spaced at least 75cm apart.
And then there are all the usual brassica issues. They will be attacked by the caterpillars of cabbage white butterflies, will get mealy aphids on the leaves and, in winter, pigeons will land on them and peck at the foliage, and poo on the plants. And there is cabbage whitefly. Of course these are not inevitable but they are likely.
But, all being well, you will have a super-healthy, tasty crop in spring. I nearly always grow purple-sprouting though most books say that the white is more tender and tasty. On the basis that more colour means more healthy I am happy with my choice and this is one of those veg that imbues a feeling of healthiness just as you eat it – even if slathered in butter – the broccoli, not me. You can now get F1 hybrid cultivars and I confess that I choose these because they tend to have a more compact habit than the older types and larger central heads. After these are cut there is a later flush of thinner shoots that are just as good, if not better, because they grow during warmer days and are more tender.
To add confusion there is also ‘Summer Purple’ which, like some of the F1 hybrids, does not need a cold period to stimulate flowering so will crop in summer. I find it rather disappointing and I think the seed strain needs stabilising. But perhaps it is just that there are so many veg when this is ready and I don’t really need it.
And so we come to calabrese (named after Calabria where it originated), and which everyone calls broccoli. I pedantically continue to maintain the distinction because they are very different plants. Calabrese is not hardy and is a summer and autumn crop. Each plant forms a large central head and all will make secondary small heads though some are bred specifically with this in mind. Unlike sprouting broccoli, this is a quick crop. You can sow from March (under glass) to June, for a succession of heads from July to November. Because the plants are neat and can be put as close as 30cm apart, this is a much better crop for raised beds and small gardens. It does suffer from all the brassica pests but, simply because the plants are not hanging around for so long, they are less likely to be affected by them. This is another case when F1 hybrids are worth the extra money because they will be reliable and crop well. Excess can be frozen if you get a glut.
What to grow
For fast crops and where space is at a premium grow calabrese. But for spring crops grow sprouting broccoli.
The seeds are quite large and easy to handle so you can easily sow ten calabrese seeds in a pot in March and repeat over the next three months. All brassicas prefer loam over multipurpose compost but it is not critical at the seedling stage. Sow the seeds, cover with compost and at 15-20c they will germinate in less than two weeks. Transplant to cell trays when the seed leaves are fully expanded and grow-on cool till they have two or three true leaves. They do not need high heat and do need light. If the leaves start to go purple they are starved so either feed them or plant them out quick. Sprouting broccoli is usually sown in May, in the same way. It is worth buying plants in trays but look for those with large leaves. Ignore any with small leaves and with compost packed with roots which may be stunted.
Don’t accept freebies
Few people sow in the soil and transplant seedlings but it is possible. Never accept any brassica seedlings grown this way because the soil may be contaminated with club root and you will infect your plot with it. The same goes for wallflowers.
When ready to plant out, choose a dull day if possible, then water the plants. Plant with a trowel and firm well after planting and then water. Protect the youngsters from slugs and snails. It goes without saying that pigeons will pounce on them. You can cover them with fleece or pest fabric to keep insects out.
Calabrese needs little attention but sprouting broccoli needs the old, fallen leaves picked up or they will just encourage snails and other pests.