Although it originated in Italy, calabrese or green broccoli – to distinguish it from white and purple sprouting broccoli – is sometimes known, confusingly, as American broccoli or plain broccoli in the supermarkets
By careful choice of variety and planting dates it is possible to have fresh calabrese from the garden for much of the year. It is not a difficult vegetable to grow and the smaller varieties are suitable for growing as a baby vegetable in even the smallest garden.
Calabrese will suffer a setback to its growth if it is transplanted from a seedbed, producing a poor-sized head. It is therefore best to start it off in pots, so that it can be planted out without disturbing the root ball.
Calendar
Like other members of the cabbage family, calabrese grows best in a rich soil. If possible, dig in well-rotted manure or garden compost before planting. If this is impractical, work in a balanced fertilizer instead. A light dressing of a nitrogen fertilizer can be given when the young plants have 6-8 leaves, to boost yields.
February-March
Make the first sowing in pots in a greenhouse or somewhere you can maintain a temperature of at least 13°C. Sow two seeds to a 7-cm pot. If both germinate, pull out the weaker one later. Keep the plants growing somewhere frost-free. The compost needs to be moist but try to avoid wetting the leaves, as they are very susceptible to downy mildew.
April-May
Plant out the first sowing after six to eight weeks. In cold areas, plant them under cloches or garden fleece.
For baby vegetables, space plants 15cm apart each way. For larger main heads, space plants 15cm apart in rows 30cm apart. This spacing will give the optimum yield of main heads. For a follow-on crop of side shoots, space them 30cm apart each way.
Water plants while in their pots and try not to disturb the root ball when planting out. Plant them deeply, so the first set of leaves are level with the soil surface.
Sow further small batches throughout April and May for a long harvest. As the weather warms up, you can start plants off in pots in a sheltered spot outdoors or sow seed directly where they are to grow.
June
In dry summers, you can improve the yield of calabrese by giving the plants a good soaking about a month or so after planting out.
Sow another batch of seeds in pots. Bear in mind that cabbage white caterpillars start to become troublesome during mid-summer and will severely damage young plants given the chance, so cover the plants with fine netting.
July
Continue to sow small batches of seed and plant out earlier sowings, protecting them at all times from cabbage whites.
Cut the main heads of earlier sowings and pick over the side shoots of the earliest batch before the flower buds start to open.
August
Make a last sowing for a crop before Christmas. Note that the plants will be killed by severe frost.
September
Plant out the late-sown plants and continue to pick over early crops.
October-December
Cover late crops planted out last month with tall cloches or garden fleece. Continue to cut main heads and side shoots of later sowings.
