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How to Grow Romanesco

Brassica oleracea var. botrytis

Half Hardy Cool Season Single Harvest

When to Start

Sow indoors 5 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 8°C.

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Growth Stages

Sow seeds
Germination ~10d
Harvest ~120d

Approximate days from start

Care Essentials

  • Feed with a nitrogen-rich fertiliser when transplanting and again when heads begin to form. Brassicas are hungry plants.
  • Romanesco is more temperamental than cauliflower — it needs consistent conditions without temperature shocks. Avoid transplant stress and keep evenly moist.

Companion Planting

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Growing Conditions

Min. soil temperature: 8°C+
Germination temperature: 10–25°C

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Spacing & Planting

Plant spacing 60 cm
Row spacing 75 cm
Sow depth 1.5 cm
Mature height 60 cm
Mature spread 60 cm

Large plants that need generous spacing for good head development. Do not crowd.

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Care Guide

Feeding
Feed with a nitrogen-rich fertiliser when transplanting and again when heads begin to form. Brassicas are hungry plants.
Watch for
  • Cabbage white butterfly caterpillars
  • Pigeons
  • Clubroot
  • Whitefly

Pests & Diseases

Pest Cabbage White Butterfly

Identification: Green caterpillars on leaves, large ragged holes, frass visible

Organic treatment:
  • Fine mesh netting (best prevention)
  • Hand-pick caterpillars
  • Encourage parasitic wasps
Chemical treatment:
  • Bacillus thuringiensis (Bt) spray
Pest Wood Pigeons

Identification: Stripped leaves, torn foliage, bird droppings nearby

Organic treatment:
  • Netting or cage protection
  • Bird scarers
Disease Clubroot Plasmodiophora brassicae

Symptoms: Wilting in warm weather despite moist soil. Swollen, distorted roots when pulled up.

Treatment: No cure. Remove and destroy affected plants. Do not compost.

Prevention: Lime soil to raise pH above 7.2. Rotate brassicas on a 4-year cycle. Start plants in clean compost in pots.

Growing Conditions

Min. soil temperature8°C
Germination temperature10–25°C
Base growth temperature5°C
Min. daylength to start10h
Photoperiod sensitivityday neutral

Frequently Asked Questions

How far apart should I plant Romanesco?
Plant Romanesco 60cm apart with 75cm between rows.
When can I harvest Romanesco?
Romanesco is ready to harvest approximately 80 days after transplanting.
Is Romanesco frost hardy?
Romanesco is classified as Half Hardy.

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