How to Grow Peppers in the UK

How to Grow Peppers in the UK: Complete Growing Guide

Peppers (sweet peppers and chillies) are rewarding crops for UK gardeners, offering colourful, flavourful fruits throughout summer and autumn. While they need warmth and protection, growing peppers in a greenhouse, polytunnel, or sunny windowsill is straightforward and productive.

Not sure when to sow? See our When to Plant Peppers UK →

Quick Growing Facts

Sowing Time: February to April indoors
Harvest Time: July to October
Growing Time: 20-30 weeks from sowing to first harvest
Difficulty: Moderate
Position: Greenhouse, polytunnel, or very warm, sheltered spot outdoors

When to Sow Peppers

Indoor sowing: February-April in a heated propagator or warm windowsill
Early sowings: February-March for greenhouse growing (need 18-21°C)
Later sowings: March-April for outdoor growing in very warm, sheltered locations
Chillies: Sow in February as they need an even longer season than sweet peppers

Soil and Compost Preparation

Container growing: Use good quality multipurpose or tomato compost
Greenhouse borders: Enrich soil with well-rotted manure or compost
Drainage: Ensure excellent drainage; peppers hate waterlogged conditions
pH level: Slightly acidic to neutral (pH 6.0-7.0)
Pot size: Final pot size should be at least 7.5-10 litres (2-3 gallons)

How to Sow Peppers

Use small pots or modules: Fill with seed compost
Sow on surface: Place 2-3 seeds per pot on the surface
Cover lightly: Cover with a thin layer of vermiculite or sieved compost
Warmth essential: Keep at 18-21°C (65-70°F) for germination
Use a propagator: A heated propagator speeds germination (10-21 days)
Good light: Move to bright, warm location once germinated
Thin to strongest: Remove weaker seedlings, leaving one per pot

💡 Top Tip

Pepper seeds germinate best with bottom heat. Place seed trays on top of a refrigerator, near a radiator, or use a heated propagator to maintain consistent warmth for faster, more reliable germination.

Potting On and Planting Out

First potting: Move to 7.5cm (3 inch) pots when 2-3 true leaves appear
Final potting: Transfer to final 7.5-10 litre pots when roots fill smaller pots
Greenhouse planting: Plant in greenhouse borders or large pots in late April-May
Outdoor planting: Only in very warm, sheltered spots after all frost risk (early June)
Harden off thoroughly: Acclimatise to outdoor conditions over 2-3 weeks
Spacing: Space plants 45cm (18 inches) apart

Ongoing Care

Watering: Keep compost consistently moist but not waterlogged; water regularly, especially when fruiting
Feeding: Feed weekly with high-potash tomato fertiliser once first fruits appear
Support: Stake tall varieties to prevent stems breaking under fruit weight
Pinching out: Pinch out growing tip when plants reach 30cm (12 inches) to encourage bushier growth
Temperature: Maintain 18-25°C for best growth; provide shade if over 30°C
Humidity: Mist plants occasionally in hot weather to aid fruit set

Common Problems

Blossom end rot: Dark patches on fruit base caused by calcium deficiency due to irregular watering. Maintain consistent moisture levels.

Poor fruit set: Often due to temperatures too high or too low. Maintain 18-25°C and ensure good pollination by gently shaking plants.

Aphids: Small sap-sucking insects. Spray with soapy water or use biological controls.

Red spider mite: Tiny mites causing yellowing leaves. Increase humidity and use biological controls.

Harvesting Peppers

Green peppers: Harvest when full-sized but still green (12-16 weeks after planting out)
Coloured peppers: Leave to ripen to red, yellow, orange, or purple (2-3 weeks longer)
Ripe = sweeter: Coloured peppers are sweeter and more nutritious than green
Cut, don't pull: Use secateurs or scissors to cut fruits with a short stem
Regular picking: Harvest regularly to encourage more fruit production
Before frost: Harvest all fruits before first frost; green ones will ripen indoors

Storage

Fresh: Store in the refrigerator for up to 2 weeks
Room temperature: Green peppers will ripen to red if kept in a warm place
Freezing: Chop and freeze raw for up to 6 months (texture changes but fine for cooking)
Drying: Thread chillies on string and hang in a warm, dry place
Preserving: Roast and preserve in oil, or make into chutney or hot sauce