Coriandrum sativum 'Slow Bolt' (Slow Bolt Cilantro)
Coriandrum sativum 'Slow Bolt' (Slow Bolt Cilantro)
Contents
Introduction & History
Slow Bolt cilantro is the answer to every cilantro grower’s chief frustration — premature bolting. This cultivar was bred specifically to extend the leaf-producing window by 2–3 weeks beyond standard coriander, giving gardeners more time to harvest fresh leaves before the plant races to flower. While no cilantro variety can be bolt-proof, Slow Bolt’s delayed flowering makes it the best choice for warm-climate growers.
History & Origin
Developed through conventional plant breeding — selecting plants that naturally took longer to bolt. Multiple seed companies have independently selected slow-bolting lines. Similar selections include 'Calypso,' 'Santo,' 'Caribe,' and 'Leisure.' The breeding reflects the reality that most home gardeners grow coriander for leaves, not seeds.
Botanical Description
Visually nearly identical to standard coriander. The key genetic difference is delayed transition from vegetative to reproductive growth: Slow Bolt produces 2–3 additional rosettes of harvestable basal leaves before sending up the flowering stalk. Plants reach 40–50 cm, slightly shorter and denser than standard coriander. Flowers are the same white-pink umbels.
Stem: Hollow, often grooved • Leaves: Alternate, compound (pinnate or palmate) • Inflorescence: Compound umbel • Height: 45 cm at maturity • Spread: 20 cm • Foliage: green • Flowers: white (late summer)
Planting & Cultivation
Identical to standard coriander: direct sow 2–3 weeks before last frost, 1 cm deep. Crush fruits before sowing. Full sun in cool climates, partial shade in warm. Succession sow every 3 weeks — even Slow Bolt will eventually bolt.
| Sun exposure | Full Sun Partial Shade |
| Soil pH | 6.2-6.8 |
| Spacing | 20 cm |
| Seed depth | 3–6 mm (surface-sow if light-dependent germinator) |
| Water needs | Moderate |
| Soil type | Well-drained, humus-rich loam; add perlite or grit for drainage |
Cultivation Details
Grow exactly as standard coriander with the advantage of 2–3 extra weeks of leaf harvest. Keep soil consistently moist — drought is the strongest bolting trigger. In hot climates, use shade cloth or plant in shade of taller crops. Begin harvesting aggressively at 15 cm — cutting stimulates lateral production and delays bolting.
Climate & Hardiness
Same cold hardiness as standard coriander — survives brief frosts to -5°C. The improved bolt resistance is most evident at 22–28°C. Above 30°C, even Slow Bolt bolts relatively quickly. Best in cool-season windows.
USDA zones: 2-11
Minimum temperature: -5°C
Indoor growing: Suitable for windowsill culture with 6+ hours light
Seasonal Care
Spring: Primary sowing season. Direct sow every 3 weeks. Water consistently. Summer: Bolting becomes inevitable in hot weather. Harvest heavily. Make new sowings for autumn. Autumn: Best growing season — cool temperatures maximize bolt resistance. Winter: Overwintered plants resume early spring before bolting.
Propagation
Seed only. Comes true from seed (bolt-resistant trait is stable). Save seed from the latest-bolting plants to gradually improve resistance. Crush fruits before sowing.
| Method | Success rate | Time | Notes |
|---|---|---|---|
| Direct sowing | 85–95% | 7–21 days | Sow after last frost, 3–6 mm deep |
| Indoor start | 90–98% | 6–8 weeks early | Use seed trays, transplant after hardening off |
| Succession sowing | — | Every 3–4 weeks | Ensures continuous harvest all season |
Diseases & Pests
Identical to standard coriander. The longer vegetative phase means more time vulnerable to foliar diseases. Maintain air circulation and water at the base. Overall pest-resistant due to aromatic oils.
Culinary Uses
Identical to standard cilantro — same flavor profile. The advantage is purely in quantity and timing: more leaves over a longer period. All standard cilantro applications apply.
| Category | Pairing suggestions |
|---|---|
| Poultry | Chicken, turkey, duck |
| Fish | White fish, salmon, prawns |
| Vegetables | Tomatoes, courgettes, aubergine |
| Dairy | Soft cheeses, butter, cream sauces |
Medicinal & Aromatherapy
Same profile as standard coriander. No medicinal difference. The extended harvest means more fresh material available.
| Compound | Properties |
|---|---|
| myrcene | herbaceous, earthy |
| linalool | floral |
| geraniol | rose-like |
| citral | lemony |
| apigenin | mild sedative flavonoid |
Container & Companion Growing
Container Growing
Same as standard coriander — minimum 20 cm deep. Sow densely for cut-and-come-again crop. The bolt resistance makes Slow Bolt the best cilantro variety for containers where heat stress from sun-warmed walls triggers rapid bolting.
• 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
• Indoor: Place on brightest windowsill (south-facing ideal); supplement with grow lights in winter
Companion Planting
Same as standard coriander. The extended vegetative phase provides ground cover and pest-deterrent aroma for a longer period before flowering.
| ✓ Good companions | Tomatoes, Peppers, Strawberries, Carrots |
| ✗ Avoid planting with | Fennel, Rue |
Common Mistakes to Avoid
1. Treating as bolt-proof — it’s bolt-resistant, not immune. 2. Growing in full hot sun in summer. 3. Neglecting consistent watering. 4. Transplanting instead of direct sowing. 5. Not harvesting aggressively enough — heavy cutting delays bolting.
Harvesting & Preservation
Expect 4–6 cut-and-come-again harvests compared to 3–4 with standard types. Same preservation methods: freeze (best), use fresh within 1–2 days. Drying is worthless. Green seeds from bolted plants are a culinary bonus.
• 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
How much longer does Slow Bolt really last?
In optimal cool conditions (18–25°C), 2–3 extra weeks — producing 4–6 harvests instead of 3–4. In hot weather above 30°C, the advantage shrinks to about 1 week. A meaningful improvement, not a miracle.
Should I still succession sow?
Yes, absolutely. No cilantro variety eliminates the need for succession sowing. Slow Bolt delays bolting, it doesn’t prevent it.
Can I save seed from Slow Bolt?
Yes — only save from the LAST plants to bolt. Over generations, this improves bolt resistance adapted to your local conditions. Keep isolated from standard coriander (10+ meters).
Seasonal Care Calendar
🌱 Spring (Mar–May)
Water: Moderate
Feeding: Light feeding
Primary sowing. Direct sow every 3 weeks. Water consistently.
☀️ Summer (Jun–Aug)
Water: Regular
Feeding: Light feeding
Bolting eventually occurs. Harvest heavily. Use shade in hot zones.
🍂 Autumn (Sep–Nov)
Water: Moderate
Feeding: Light feeding
Best growing season — cool temps maximize bolt resistance.
❄️ Winter (Dec–Feb)
Water: Light
Feeding: No feeding
Autumn-sown plants produce through winter in mild zones.
Slow Bolt cilantro extends the leaf harvest window by 2–3 weeks through genetically delayed flowering. Identical flavor to standard cilantro. Still requires succession sowing — bolt-resistant, not bolt-proof.
Quick Reference: Coriandrum sativum 'Slow Bolt'
Key Principles: Right location, well-drained soil, regular harvesting to promote growth, and appropriate winter protection for tender species.