Chillies: How to Start (Part 1)
Chillies are a rewarding crop for New Zealand gardeners. Growing them in a greenhouse lets you extend the season, protect plants from wind, rain, and frost, and achieve higher yields of vibrant, flavourful fruit. This guide walks you through everything you need to know to grow chillies in a greenhouse in NZ—from when to sow seeds to when to harvest.
1. Planning to Grow Chillies
Before you begin, take time to plan. Chillies range from mild capsicums through to fiery varieties like habaneros and bird’s eye chillies. Choose varieties based on flavour, heat level, and how you intend to use them. Medium-heat types such as cayenne or jalapeño are great for beginners.
Decide how many plants to grow depending on your greenhouse size and how much harvest you want. A small NZ greenhouse can comfortably hold 10–20 plants; larger structures can house more. Avoid overcrowding as it restricts airflow and increases the risk of disease.
Growing chillies in a greenhouse in New Zealand is particularly worthwhile. The controlled environment extends the growing season, keeps temperatures more stable, and protects plants from harsh weather. This results in earlier harvests and healthier plants than outdoor growing alone.
2. Starting from Seed
Seeding timeline:
• In New Zealand, sow chilli seeds between September and January, giving plants enough warmth and daylight to grow strong before flowering.
Chilli seeds need warmth, humidity, and good light to germinate. Maintain soil at 25–28°C. A heat mat is helpful, and covering trays with a propagator lid retains moisture.
Use a light, fast-draining seed-raising mix. Sow seeds about 0.5 cm deep, water gently, and keep the mix moist but not saturated. Germination usually takes 7–14 days, depending on the variety.
Once seedlings emerge, give them plenty of bright light. NZ winter daylight is often insufficient, so consider LED or fluorescent grow lights for 12–16 hours a day to keep seedlings compact and healthy.
Common issues:
• Poor germination: usually low temperatures or old seeds
• Damping-off: caused by overwatering—ensure airflow and clean seed mix
• Leggy seedlings: not enough light—use grow lights if necessary
3. Growing Conditions in the Greenhouse
Chillies grow best in warm, stable conditions: daytime temperatures of 20–30°C and nights above 15°C. A greenhouse helps maintain these conditions through New Zealand’s cooler months.
Light is crucial. Chillies need 12–14 hours of light daily. In darker periods, supplementary LED lighting is beneficial.
Use fertile, well-draining soil enriched with compost or well-rotted organic matter. Aim for a slightly acidic to neutral pH of 6–7. Water consistently, allowing the top layer of soil to dry slightly between waterings to avoid root rot. Mulching helps retain moisture and moderate soil temperature.
Humidity and airflow matter. High humidity encourages fungal disease, while poor airflow reduces pollination. Use vents, fans, or leave doors open to maintain circulation. Humidity around 50–70% is ideal, with adjustments made for the season.
