How to grow perennial rocket
Overview
Perennial rocket (Diplotaxis tenuifolia) is a hardy, perennial brassica grown for its peppery, deeply lobed leaves. Unlike annual rocket, it regrows from a woody crown each season, providing a longer harvest period with less bolting in warm weather.
Varieties
- Perennial Rocket 'Sylvetta' — The standard wild rocket type with deeply lobed, peppery leaves; very hardy and long-lived.
- Perennial Rocket 'Wasabi' — A slightly hotter, more pungent variety bred for extended leaf production in warm weather.
Soil Preparation
Perennial rocket prefers a slightly acidic to neutral pH (6.0–7.0) in well-drained, loamy soil enriched with compost or well-rotted manure. Avoid heavy clay or waterlogged beds; improve drainage with raised beds or coarse sand if needed.
Growing Guide
Sow seed directly into well-drained, fertile soil at 5 mm depth, 20 cm apart in rows or broad beds. Perennial rocket thrives in full sun but appreciates light afternoon shade in hot zones. Water deeply once or twice a week, allowing the topsoil to dry between waterings. Cut back flower stems as soon as they appear to keep leaves tender and productive.
Sowing
Sow seed 5 mm deep, 20 cm apart, directly into prepared beds or punnets. Germination takes 5–10 days at 15–20°C. Thin to 30 cm apart for strong plants. Direct sowing is preferred over transplanting to avoid root disturbance.
Care
Feed every 4–6 weeks with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) during active growth. Remove yellowing or damaged leaves to reduce pest habitat. Cut flower stems promptly to prolong leaf production and prevent bolting.
Companion Planting
Plant near beetroot, carrots, onions, and herbs like dill or coriander to deter pests. Avoid planting near other brassicas (cabbage, kale, broccoli) to reduce shared pest and disease pressure.
Common Pests & Risks
Flea beetles cause small holes in leaves; control with diatomaceous earth or fine mesh netting. Aphids cluster on new growth; blast off with water or use insecticidal soap. Caterpillars (e.g., cabbage white butterfly) can be hand-picked or managed with Bacillus thuringiensis (Bt).
Harvesting
Harvest young, tender leaves from the outer rosette when plants are 15–20 cm tall, usually 6–8 weeks after sowing. Regular cutting every 2–3 weeks encourages fresh growth and prevents the leaves from becoming tough or bitter.
In the Kitchen
Use fresh leaves in salads, pesto, or as a peppery garnish. They wilt quickly, so add at the end of cooking. Store unwashed in a damp cloth in the fridge for up to a week.
Troubleshooting
Yellow leaves: overwatering or poor drainage — reduce water and improve soil. Brown leaf edges: heat stress or underwatering — provide shade and consistent moisture. Stunted growth: nitrogen deficiency — feed with liquid fertiliser. Bolting: warm weather or missed cuts — cut flower stems immediately and harvest more often. Holes in leaves: flea beetle damage — use fine mesh or diatomaceous earth.