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Broccoli (Calabrese)

Brassica oleracea Italica group

INTRODUCTION

Calabrese (meaning from Calabria) or Broccoli, originated in the eastern Mediterranean during Roman rule. It arrived in England during the 18th century and is a highly nutritious brassica. Calabrese is grown for its large immature flower head, which if left uncropped will turn to flower.

Using a selection of varieties sown and planted at different times, it is available for harvesting from late May (with protection) until well into the autumn. It is a very straightforward and rewarding vegetable to produce and is incredibly versatile in the kitchen.

Soil Preparation

Calabrese or Broccoli thrives in fertile, moisture-retentive but well-drained soil. The growing area should be sunny but sheltered from strong winds.

The addition of garden lime may be required to maintain a soil pH of around 6.5. Do not grow in a freshly manured site.

Ensure the ground is well prepared the previous autumn and has sufficient time for the soil to settle.

Sowing & Planting

Calabrese can be sown directly into a seedbed for later transplanting but a better method of raising plants is to sow into modules or seed trays.

Sow seed from February (early varieties) through to June (late varieties) into your chosen container and cover to a depth of approx. 0.5cm. Keep at a temperature of between 5c and 15c. When seedlings are large enough to handle, transfer into a larger container. A 9cm pot is ideal.

Gradually harden plants off before planting. Planting out should be from March, weather permitting, for early harvests continuing until July for autumn harvesting, at a spacing of 45cm/18inches between plants and between rows.
Ensure plants are deep enough and well firmed in, they dislike loose soil.

Do not allow sowing temperatures to rise above 25oc, Brassica seed can go into dormancy at high temperatures.

Growing & General Cultivation

After planting, water well. Once established Calabrese require regular watering to maintain growth. Protect establishing plants with netting to guard against attack from pigeons.

Keep growing crops weed-free and stake plants as they grow if required.

Feed once during the growing season and mulch plants if possible.

Try and avoid growing Calabrese or any other Brassica plant type on the same ground the following year. Crop rotation is an important factor in helping to protect against disease.

Pests & Diseases

Calabrese tends to suffer from all common pests and diseases associated with other Brassicas.

Slugs and Snails can be a problem for young plants - for remedies - see product directory.

Other pests can include Caterpillars (cabbage white). Eggs will appear on the underside of leaves during summer and can be removed by hand. Caterpillars will devastate crops within days if left uncontrolled. Chemical control is available - see product directory.

Cabbage Whitefly (not to be confused with greenhouse whitefly) can be unsightly but shouldn't affect cropping potential.

Diseases can include, Downy mildew which shows as yellow patches on foliage and affected leaves should be removed. To prevent, ensure good air circulation and low humidity. Powdery Mildew is a white powdery deposit that can cover stems and foliage. It is usually associated with dry weather and to prevent, avoid plants from drying out. Remove affected foliage as needed or in severe outbreaks, use a suitable fungicide - see product directory.

Clubroot, a soil-borne fungal disease, affects Calabrese which causes swelling and distortion of roots. It results in poor plant growth and subsequent loss of harvest. Avoid using ground previously used for brassica crops and ensure correct soil pH (6.5).

Add garden lime as required. As an alternative, grow a Clubroot resistant variety such as 'Monclano'.

Harvesting

Once Calabrese heads have reached your desired size, cut with a sharp knife as required. If plants are left, you will be able to crop secondary shoots that will appear lower down the stem.

Be warned, Calabrese can mature all at the same time and in warm weather can 'go over' very quickly. A simple solution to having a glut is to sow/plant little and often. Calabrese freezes well.