Diplotaxis tenuifolia (Wild Rocket)
Diplotaxis tenuifolia (Wild Rocket)
Contents
Introduction & History
Wild rocket is the perennial cousin of common arugula, offering a more intense, nutty-peppery flavour that holds through summer heat far better than its annual relative. Slow to bolt and persistent in the garden, it forms a woody-based clump that returns year after year, providing a reliable supply of narrow, deeply serrated leaves.
History & Origin
Native to southern Europe and western Asia, wild rocket has been foraged from Mediterranean hillsides for millennia. Unlike cultivated arugula, it was never widely domesticated until modern demand for 'wild' salad greens grew in the 1990s. It now appears in commercial baby leaf mixes and is increasingly grown in home gardens for its superior heat tolerance.
Botanical Description
Herbaceous perennial forming a semi-woody base. Leaves are deeply pinnate with narrow, elongated lobes, darker green and more finely divided than common arugula. Plants grow 30–60 cm tall when flowering, bearing bright yellow four-petalled flowers. The overall habit is more upright and bushy than Eruca vesicaria, with wiry stems.
Stem: Semi-woody to woody at base • Height: 40 cm at maturity • Spread: 25 cm • Foliage: dark green • Flowers: yellow (summer)
Planting & Cultivation
Sow seeds on the surface or barely covered (light aids germination) in spring after last frost. Space plants 20–25 cm apart. Germination takes 7–14 days and can be erratic — be patient. Alternatively, start indoors 6 weeks before last frost and transplant. Once established, plants self-sow moderately. Can also be propagated by dividing mature clumps in early spring.
| Sun exposure | Full Sun Partial Shade |
| Soil pH | 6.0-7.5 |
| Spacing | 25 cm |
| Seed depth | 3–6 mm (surface-sow if light-dependent germinator) |
| Water needs | Low |
| Soil type | Well-drained, humus-rich loam; add perlite or grit for drainage |
Cultivation Details
Grows in almost any well-drained soil, tolerating poor, rocky ground. Full sun to partial shade. Unlike annual arugula, wild rocket handles summer heat without bolting prematurely, though leaves grow more slowly in midsummer. Cut plants back to 5 cm in midsummer to rejuvenate foliage. Fertilise lightly — too much nitrogen reduces flavour intensity.
Climate & Hardiness
Perennial in USDA zones 5–9, surviving winters to about −20°C once established (the woody base is remarkably hardy). In zones 3–4, treat as an annual or provide heavy mulch. Tolerates summer heat well up to 35°C, continuing to produce leaves when annual arugula has long bolted.
USDA zones: 5-9
Minimum temperature: -15°C
Drought tolerance: Yes — established plants tolerate dry spells
Seasonal Care
Spring: divide established clumps if crowded; begin harvesting new growth. Summer: harvest regularly, cut back flower stalks to promote leaf production. Autumn: continues producing well into autumn frosts — often the best harvest season. Winter: mulch crowns in zones 5–6; in mild climates, leaves persist through winter.
Propagation
By seed (surface-sow, light-dependent germination), division of established clumps in spring, or stem cuttings from semi-woody basal growth in late spring. Seeds are tiny — mix with sand for even distribution. Self-sows moderately if flowers are left. Division every 3–4 years rejuvenates old plants.
| Method | Success rate | Time | Notes |
|---|---|---|---|
| Stem cuttings | 70–90% | 2—4 weeks | Softwood in spring, semi-ripe in summer; 8–12 cm |
| Division | 95%+ | Immediate | Split established clumps in spring or autumn |
| Seed | 50–80% | 14–28 days | Some require cold stratification; germination variable |
| Layering | 80–90% | 6–12 weeks | Pin low branch to soil; sever when rooted |
🌍 Distribution Map
Native origin: Mediterranean
Diseases & Pests
Flea beetles can be problematic but cause less damage than on annual arugula due to the plant's vigour. Aphids occasionally colonise flower stalks. Generally very pest-resistant once established. Downy mildew in humid climates — ensure good air circulation. No serious disease problems in most gardens.
Culinary Uses
The intense, nutty-peppery flavour makes wild rocket a premium salad green, excellent paired with aged cheeses, cured meats, and robust vinaigrettes. Toss onto fresh pizza, stir into risotto at the end, or blend into a distinctive pesto. The yellow flowers are also edible with a mild mustard flavour. In Italian cuisine, it is the traditional rucola selvatica.
| Category | Pairing suggestions |
|---|---|
| Poultry | Chicken, turkey, duck |
| Fish | White fish, salmon, prawns |
| Vegetables | Tomatoes, courgettes, aubergine |
| Dairy | Soft cheeses, butter, cream sauces |
Medicinal & Aromatherapy
Similar nutritional profile to common arugula — rich in vitamins C and K, folate, and glucosinolates. Traditionally used in Mediterranean folk medicine as a digestive tonic. The higher glucosinolate content compared to annual arugula gives it stronger potential antioxidant properties.
| Compound | Properties |
|---|---|
| myrcene | herbaceous, earthy |
| linalool | floral |
| geraniol | rose-like |
| citral | lemony |
| apigenin | mild sedative flavonoid |
Container & Companion Growing
Container Growing
Grows well in deeper containers (25+ cm) due to its taproot. Use well-draining potting mix. Less suited to shallow windowsill trays than annual arugula because of its perennial root system. Water moderately — tolerates some drought. Feed monthly during the growing season with half-strength liquid fertiliser.
• Minimum pot size: 20–25 cm Ø, 5 L+
• Shallow roots; frequent watering needed
• Use free-draining potting compost with 20–30% perlite or grit
• Ensure drainage holes; stand on pot feet to prevent waterlogging
• Feed with dilute liquid fertiliser (half-strength) every 2–3 weeks in growing season
Companion Planting
Good companion for tomatoes, peppers, and eggplant — its small flowers attract beneficial hover flies and parasitic wasps. Plant near fruit trees as a living mulch. Avoid grouping with other brassicas to minimise shared pest problems.
| ✓ Good companions | Tomatoes, Peppers, Strawberries, Carrots |
| ✗ Avoid planting with | Fennel, Rue |
Common Mistakes to Avoid
Expecting it to grow as fast as annual arugula — wild rocket is slower to establish but far longer-lived. Sowing seeds too deep (they need light). Over-fertilising, which produces lush but bland leaves. Not cutting back flower stalks, which diverts energy from leaf production.
Harvesting & Preservation
Harvest individual leaves or cut the entire rosette to 5 cm — it regrows vigorously. Leaves are smaller and more flavourful than annual arugula. Best used fresh; can be stored refrigerated for up to a week. For preservation, make pesto or herb oil and freeze. Dried wild rocket loses most of its flavour.
• Time of day: Early morning, after dew has evaporated but before intense midday heat volatilises essential oils
• Growth stage: Just before flowering, when essential oil concentration peaks. Once flowers open, the plant redirects energy from leaf production
• Season: Spring-Autumn
• Part harvested: Leaves
• Harvest rule: Never remove more than ⅓ of the plant at once; this ensures continued vigorous regrowth
• Technique: Cut stems cleanly above a leaf node with sharp scissors or secateurs. Tearing damages tissue and invites disease
| Method | Process | Shelf life | Best for |
|---|---|---|---|
| Air drying | Tie bundles, hang upside down in warm, dark, airy space | 6–12 months | Most herbs |
| Oven / dehydrator | Spread on trays, 35–45°C until crisp | 6–12 months | Fleshy-leaved herbs |
| Freezing (whole) | Blanch 5s, ice bath, pat dry, freeze flat on tray | 6 months | Basil, chives, parsley |
| Freezing (oil cubes) | Chop fine, pack into ice cube tray, cover with olive oil | 6 months | Any culinary herb |
| Herb salt | Layer herb and coarse salt 1:4, dry and grind | 12+ months | Rosemary, thyme, sage |
| Infused vinegar | Pack jar, cover with warm vinegar, steep 2–4 weeks | 6 months | Tarragon, dill, basil |
| Infused oil | Fill jar with dried herb, cover with oil, steep 4–6 weeks | 3–6 months | Rosemary, thyme, chilli |
Frequently Asked Questions
What's the difference between wild and regular arugula?
Wild rocket (Diplotaxis tenuifolia) is a perennial with narrower, more deeply lobed leaves and a stronger flavour. Regular arugula (Eruca vesicaria) is an annual that grows faster but bolts quickly in heat.
Will wild rocket survive winter?
In zones 5–9, yes. The woody base is hardy to about −20°C. In colder zones, mulch heavily or treat as an annual.
Why is my wild rocket so slow to germinate?
Wild rocket seeds need light to germinate and take 7–14 days, sometimes longer. Surface-sow and keep consistently moist. Patience is key.
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Moderate
Feeding: Regular feeding
☀️ Summer (Jun–Aug)
Water: Regular
Feeding: Regular feeding
🍂 Autumn (Sep–Nov)
Water: Moderate
Feeding: Light feeding
❄️ Winter (Dec–Feb)
Water: Light
Feeding: No feeding
A hardy perennial rocket with intense nutty-peppery flavour, far more heat-tolerant than annual arugula. Forms a woody base surviving to −20°C in zones 5–9. Slower to establish but produces for years with minimal care. Cut back midsummer for fresh foliage.
Quick Reference: Diplotaxis tenuifolia
Key Principles: Right location, well-drained soil, regular harvesting to promote growth, and appropriate winter protection for tender species.