Romanesco cabbage: Sowing, planting and harvest calendar

Sow Romanesco under cover in spring for varieties suited to summer or autumn harvests. Adjust the date to your climate and the seed packet instructions. Use small pots or a modular tray with drainage holes, filled with well-drained seed compost.

Sow one seed per module at the depth indicated on the packet and cover it. Place the containers somewhere bright, at a temperature suitable for germination. Keep the compost moist without waterlogging it and provide good light after emergence.

Once young plants are well developed, gradually acclimatise them to outdoor conditions before transplanting. Prepare fertile, well-drained soil in sun and plant when conditions are suitable. Adjust spacing to the variety and feeding to the condition of the soil.

Check the root balls before planning to plant out: they should hold together without roots remaining cramped in small modules for a long time. A growth check caused by lack of water or late transplanting can hinder head formation. Label each batch with the variety and date. To spread out harvesting, raise several small batches suited to the season rather than sowing a large quantity at once.

For summer or autumn romanesco varieties, outdoor sowing usually takes place in spring, when conditions allow germination. Follow the seed packet and adjust the timing to the variety and climate. Choose a sunny spot with fertile soil that retains moisture without becoming waterlogged.

Sow in a small seedbed at the depth stated on the packet. Thin the seedlings after germination to give them room to develop. Then transplant them to their final position, generally leaving 45–60 cm between plants depending on the variety. Seeds sown directly in their final position also need thinning to this spacing.

Water regularly to keep the soil moist. Watch for slugs and caterpillars; suitable insect-proof mesh can protect plants from butterflies that lay eggs on brassicas. Avoid routine treatments without first identifying the problem.

A nursery bed holds young plants temporarily rather than being their final site: mark the rows so you can prepare the next stage in time. If the bottom of the drill is dry, moisten it before sowing to avoid leaving seeds in dry soil. Remove competing weeds without damaging the roots. Check plants after dry spells, as an early shortage of water can slow their development.

Plant young romanesco when their development and outdoor conditions are suitable. Summer or autumn varieties are usually transplanted in spring or early summer, depending on sowing time and climate. Autumn planting for a spring harvest does not suit every variety: follow the seed packet or supplier's advice.

Gradually harden off plants raised under cover. Choose a sunny spot with fertile, well-drained soil, adding mature compost if needed. Water the root balls before planting and handle them without damaging the roots.

Generally leave 45–60 cm between plants, depending on the variety. Set them with the lowest leaves close to the soil surface, firm the soil around the roots and water thoroughly. Keep the soil consistently moist without waterlogging it and watch for brassica pests.

Young plants of this cauliflower type can generally be moved when about 10 to 15 cm tall, provided their roots are well developed. Prepare the holes before taking the root balls out so they do not dry out while waiting. Firm the soil around the roots without compressing wet ground into a solid mass. After watering, check that plants remain upright and the root balls are in good contact with surrounding soil.

Harvest romanesco when the head is sufficiently developed, firm and compact, before the florets start to separate. The season depends on the variety, sowing time and climate; it is often in summer or autumn. Do not wait for a colour change before deciding to harvest.

Use a sharp knife to cut the stem below the head, keeping a few leaves to protect it. Ideally use it soon after harvesting; it can be kept in the refrigerator for a few days. The florets can also be blanched and frozen using a method suitable for cauliflower.

Look at the spiral points and the gaps between them: they should remain tightly packed, without stems lengthening between the florets. Once a head approaches the size expected for the variety, check it frequently rather than always waiting for the largest possible size. Several plants from one batch may be ready together, so start with the most advanced heads. Support each head while cutting, then place it gently in a basket to avoid breaking the points. Remove damaged parts when preparing it and keep the harvest cool until you use it.