Best Chilli Pepper Varieties for Scotland

In Scotland, chillies are a greenhouse crop. Outdoors, fruiting may be reduced, especially in cooler summers, so the real limits are greenhouse or windowsill space and how much heat you want. Those two things, not hardiness, decide the variety.

What Scotland means for the choice

For the best crop, grow chillies in a greenhouse, polytunnel or sunny conservatory. They tolerate a minimum of about 12°C but grow better above 15°C, and all six varieties here are rated H1cThe RHS's H1a–H7 scale for how much cold a plant can survive outdoors, H1a being tender indoor-only and H7 hardy anywhere in the UK. Full definition →, so none copes with frost or cold any better than the others. Two things follow for choosing. First, space under glass is limited, so plant size and yield per plant matter. Second, a chilli's heat depends on growing conditions as well as variety, so the Scoville figures below (SHU, the standard heat scale) are what each can reach, not a promise in a dull summer. The chilli growing guide covers sowing, warmth, pollinating and feeding.

All six hold the RHS Award of Garden Merit (AGMThe RHS's Award of Garden Merit: a UK-wide trials award for reliable performance, not a Scotland-specific recommendation. Full definition →), a UK-wide award rather than a Scottish one.

Fuego

Fuego is a hot cayenne, with long fruits up to 15cm that turn from green to fiery red in summer. It stays within 0.1–0.5m, so it fits a greenhouse shelf or a pot, and at 30,000–50,000 SHU it's hot without being extreme. That balance makes it the safest single choice.

For a windowsill or small space: Prairie Fire and Loco

Prairie Fire is a compact, bushy plant up to 30cm, recommended for a sunny windowsill or patio container as well as a greenhouse border. It's also by far the hottest, at up to 1,000,000 SHU. Loco is a compact plant with colourful fruits and less heat than Fuego, 20,000–30,000 SHU, for chillies you can use every day.

For a big crop: Hot Thai

Hot Thai gives up to 200 small, hot chillies per plant, the one variety here with a yield figure, which makes it the pick for drying, freezing or pickling a batch. It's a taller plant, 0.5–1m, so give it room and good airflow under glass to keep grey mould down.

For mild peppers: Hungarian Hot Wax

Hungarian Hot Wax is the mildest here, 5,000–15,000 SHU, with large fruits that have a hint of citrus. Heat also varies with how ripe the fruit is.

For more heat: Apache

Apache, an F1 hybridThe first-generation offspring of two specific, deliberately chosen parent plants, bred for a predictable, uniform result but not worth saving seed from. Full definition →, is rated at 80,000 SHU by the RHS, above Hot Thai but far below Prairie Fire, on a plant within 0.1–0.5m. Gardener's World calls it "medium heat", so it may come out milder than that figure suggests.

Which one for your situation

• One reliable chilli for the greenhouse: Fuego.
• The hottest possible, on a windowsill: Prairie Fire.
• Everyday heat in a small space: Loco.
• The most chillies from one plant: Hot Thai.
• Mild peppers: Hungarian Hot Wax.
• Plenty of heat without going to extremes: Apache.

Under glass, any chilli can get aphids, whitefly and red spider mite, and uneven watering causes blossom end rot. Variety makes no difference to these.

Common questions

Sources