How to grow calendula
Overview
Calendula is a versatile cool-season herb grown for its edible petals and steady kitchen harvests. It thrives in full sun with consistent moisture and rewards regular picking to keep it productive. A reliable self-seeder that suits both garden beds and containers.
Varieties
- Calendula officinalis 'Indian Prince' — Deep orange-red petals with dark centres; popular in Australian gardens for its rich colour.
- Calendula officinalis 'Pink Surprise' — Unusual soft pink blooms; a conversation starter in NZ borders.
- Calendula officinalis 'Resina' — High resin content, valued for medicinal use; a favourite among herb growers.
Soil Preparation
Calendula prefers neutral to slightly acidic soil (pH 6.0–7.0) with good drainage. Enrich with well-rotted compost or aged manure before planting. Avoid heavy clay; if needed, add coarse sand or raise beds to improve drainage.
Growing Guide
Sow calendula seed directly 6mm deep in well-drained soil, spacing 20–30cm apart. For best growth, position in full sun with moderate water — avoid waterlogging. In cool zones, start after last frost; in warm zones, sow in autumn for winter blooms. Pinch out early tips to encourage bushiness. Thin seedlings to 25cm apart once true leaves appear.
Sowing
Sow seeds 6mm deep, 20–30cm apart, in rows 30cm apart. Germinates in 7–14 days at 15–20°C. Direct sow is easiest; transplant only if needed for early starts. Soak seeds for 2 hours before sowing to speed germination.
Care
Feed calendula monthly with a balanced liquid fertiliser (e.g., 10-10-10) during active growth. Deadhead spent flowers weekly to prevent excessive self-seeding and encourage rebloom. Cut back leggy stems by one-third after the main harvest to trigger a second flush.
Companion Planting
Calendula is a strong companion for tomatoes, beans, and brassicas, repelling aphids and attracting beneficials. Avoid planting near fennel, which can inhibit its growth. It also works well alongside carrots and lettuce in mixed beds.
Common Pests & Risks
Aphids cluster on new growth — hose off or use insecticidal soap. Powdery mildew appears in humid, crowded conditions; improve airflow and avoid overhead watering. Slugs may damage young seedlings; use iron-based bait or barriers.
Harvesting
Harvest calendula petals when flowers are fully open, typically in the morning after dew dries. Pick regularly to extend blooming — every 2–3 days during peak. Use fresh or dry petals in a single layer on a screen for later use.
In the Kitchen
Use fresh calendula petals in salads, rice dishes, or as a natural yellow dye for butter and cheese. Dry petals for tea or infusions — store in an airtight jar away from light. Avoid using the bitter green base of the flower.
Troubleshooting
Yellow leaves: overwatering or poor drainage — reduce water and improve soil. Brown edges: underwatering or heat stress — increase water and mulch. Stunted growth: nutrient deficiency — feed with balanced fertiliser. Powdery mildew: high humidity — space plants and avoid wetting leaves. Few flowers: too much shade or not deadheading — move to sun and pick regularly.