Broccoli is just one cultivar of the wild cabbage family, which was found around the North and West coasts of the Mediterranean, before domestication thousands of years ago.
While Broccoli is the common name used in the shops for this vegetable, confusingly you sometimes find it under the name Calabrese in some seed and plant catalogues.
In fact, there are two main different groups of Broccoli plants which are:-
Sprouting Broccoli or Brassica oleracea Cymosa group.
This type of Broccoli is sown in the Spring and usually eventually harvested in late Winter and early Spring. In other words, it is a group of hardy, over-wintering varieties of Broccoli to eat in late Winter and Spring. But just to complicate matters, there are now sprouting broccoli cultivars that are ready for eating in the Autumn.
Calabrese or Italian Sprouting Broccoli, or Brassica oleracea Italica group.
This type of Broccoli is sown in the Spring and harvested in the Autumn and early Winter, as it is not frost hardy. Some catalogues also list the Romanesco varieties (look rather like green cauliflowers), in this group. The edible spears are usually shades of green.
Health benefits of broccoli include Sulphoraphone. This anti-cancer plant compound in broccoli and most other members of the cabbage family, for the most anti-cancer effect, requires that the enzyme “myrisubase” is not destroyed by cooking at high temperatures. Steam instead for only 5 minutes or even eat raw. Also contains vitamins A, C, K, B-complex, iron, zinc, phosphorus, phyto-nutrents.
Both groups of Broccoli are grown in similar ways. They can grow up to 1 m high when fully grown.
The ground should have been prepared well in advance to allow it to become quite firm and give the plants some stability to resist the wind. Dig in manure, if available, in the late Autumn.
Sow the seeds in March for Autumn and early Winter “heading” varieties, or April for over wintering types in individual cells or pots in a cool greenhouse. In the North of the UK, transfer them to a cold frame in May and plant them out in their final positions in June. In the South of the UK, you can try sowing the seed in April directly in a seed bed, before transplanting into their final positions in May or June.
The plants should be transplanted into their final positions when they are about 10 cm tall. Leave about 45 cm between the plants and the rows.
It is best to transplant your Broccoli plants on a dull, cloudy day and water the plants in well. If you try and transplant them on a hot, sunny day, they will loose so much moisture that they will droop through stress from lack of water. If you really have to transplant on a sunny day, try and provide some shading with netting or fleece.
Protect all plants immediately after planting. If you expect to have problems withcabbage root fly, fit collars made from a 15 cm square of old carpet underlay. Cut a slit in the underlay square, halfway through. Then fit it onto the Broccoli with the stem in the middle of the underlay square. Sprinkle slug and snail pellets around the plants, or fit plastic tubes to prevent slug attack. Finnish off by erecting medium mesh netting, about 1 cm square, over and around the plants to fend off cabbage white butterflies. You should hang your protective netting about a 1 m above the ground to allow the broccoli to grow to its full height. Using these physical protective measures to protect your plants, will eliminate the need for pesticides.
Regularly inspect the growing plants to make sure that no slugs, snails or cabbage white caterpillars have managed to get into your protective cage. If you spot an infestation of large aphids, either “squish” them or dislodge them with a hose or spray with a suitable pesticide. Water as necessary in hot weather in the evening.
Both types of Broccoli should be harvested while the flower florets are still closed. When you have harvested the primary florets, you should be able to pick further crops in the following weeks.
Remember that you can also eat the smaller, tender leaves as you would do for cabbage leaves. This can be especially useful with the Sprouting types of Broccoli when there may not be much in the way of spring greens available in your plot.
If the florets are left, they will start to flower with lots of small yellow flowers. It is therefore best to keep on picking the florets before they reach the flowering stage.
Pests and diseases. Cabbage root fly, slugs, snails, aphids and the cabbage white butterfly have all been discussed above.
Pigeons. These birds can strip the leaves from over wintering brassicas. Therefore defeat them by leaving the netting protecting your valuable crop.
Clubroot can also be a problem in some locations. Clubroot is a fungus that can live in the ground for many years and will immediately infect any new brassicas planted in infected soil. It causes the roots to become swollen and distorted and the brassicas are stunted. There is no cure but measures can be taken to limit the effects and the spread of the disease.
Be very wary of buying-in plants that are not growing in sterile soil, such as peat. You do not want to bring in contaminated soil to your plot. Much better to grow your own plants from seed using sterile soil.
Sprinkle a handful of garden lime round the planting position, if you know that there is a clubroot problem in the soil.
A plant gown in a small pot of sterile compost and then transplanted, will most likely succeed even in contaminated soil.
Always burn the roots of brassicas after cropping. Never put the old roots into a compost heap as this could transfer clubroot to other areas.
Suggested varieties of Sprouting Broccoli.
Rudolph. This is an early season variety.
Purple and White sprouting Broccoli. These are mid to late season varieties.
Claret. This is a late season variety.
Suggested varieties of the Calabrese Type of Broccoli.
Corvet F1. This is an early variety.
Romanesco Veronica F1. In seed catalogues you will find it either under cauliflowers or broccoli or even calabrese. In any event, it is the best tasting variety, with the lime-green curds arranged in a spiral of symmetrical cones, rather like a fractal. It is very surprising that it is seldom seen in the supermarkets. It is slightly smaller than the standard cauliflower.
Just to complicate matters, there is now a hybrid between a calabrese and a Chinese kale, Kailaan. Also known as stem broccoli.
Brokali Appolo F1. This grows to about 60 cm tall with a spread up to 80 cm, and should be ready in about 80 days from planting out. When ready, cut the central head first to encourage the side shoots, which will extend the cropping period. It has soft and tender stems and flower buds, with a delicious flavour.