Thai chile
Capsicum annuum
Also known as: Prik kee noo, Thai pepper, Bird pepper (note: also used for C. frutescens types), Prik chee fa
Quick facts
- Category
- fruiting
- Difficulty
- beginner
- Days to harvest
- 80 to 100 days
- Harvest type
- continuous production over weeks or months
- Spacing
- 45 cm between plants
Environment
- Temperature
- 20–32°C
- pH
- 6 to 6.8
- EC (hydroponic)
- 1.8 to 2.6 mS/cm
- Daily light
- 22 to 30 mol/m²/day (strict, will fail outside this range)
Climate and zones
- USDA zones
- 5 to 12 (winter low around -29°C or warmer)
- Frost tolerance
- frost sensitive (dies at first frost)
- Season
- warm (summer crops, frost-sensitive)
Viable growing environments:
- outdoor in growing season (annual)
- unheated greenhouse / hoop house
- heated greenhouse
- indoor (heated home)
- indoor hydroponics under grow lights
USDA zone bounds reflect outdoor year-round survival. Anywhere outside the bounded zone range, this crop still grows as an annual in the warm months (outdoor_seasonal), under cover (greenhouse), or indoors under lights.
Growing systems
Thai chile works in:
- drip / Dutch buckets
- media bed (ebb and flow)
- soil bed
Growing media
The substrate the roots sit in. Choice depends on the system (clay pebbles don't fit NFT channels; rockwool isn't used in media beds) and the crop (thai chile works in the media listed below).
| Medium | pH effect | Water retention | Bacterial surface |
|---|---|---|---|
| Expanded clay pebbles (LECA) | neutral / inert | low | high |
| Coco coir (Coconut coir) | slightly acidic | high | moderate |
| Perlite (Expanded volcanic glass) | neutral / inert | very low | low |
| Rockwool (Mineral wool) | alkaline until pre-soaked | very high | low |
| Soil-based mix (Potting soil) | varies by source | high | high |
Bacterial surface area matters for aquaponics: clay pebbles, lava rock, and pumice double as biofilter substrate. Low-surface media (rockwool, perlite, pea gravel) work in hydroponics but need a separate biofilter in aquaponics.
Nutrient demand by stage
NPK ratios are relative weights at each growth stage; the nutrient mix calculator scales them to absolute grams or ml. EC targets shift through the plant's life: seedlings need a much lighter solution than fruiting adults.
| Stage | N | P | K | EC target (mS/cm) |
|---|---|---|---|---|
| seedling | 2 | 1 | 1 | 1.2 |
| vegetative | 3 | 1 | 2 | 1.8 |
| flowering | 1 | 2 | 3 | 2.2 |
| fruiting | 1 | 2 | 3 | 2.4 |
Companion-growing notes
- Heavy uptake of potassium, calcium. Co-grown crops with the same demand will end up deficient even at "correct" EC. Plan around this in shared reservoirs.
Aquaponics suitability
Compatible with typical aquaponics nutrient profiles. Fish waste provides enough nitrogen for healthy growth; supplemental potassium, calcium, and iron may still be needed depending on fish stocking density.
Care notes
A compact, prolific pepper for small hydroponic systems. Culture is identical to bird's eye chiles. EC 2.0-3.0 mS/cm. pH 5.8-6.5. Temperature: 24–32°C. High light (DLI 18-25 mol/m2/day). Plants are small enough for windowsill, countertop, or vertical growing. From transplant to first fruit: 70-90 days. Each plant produces 100-200+ small peppers over a season. Harvest green for green curry paste, red for red curry paste and dried uses. The tiny peppers dry quickly: spread on a screen or dehydrate at 55°C until brittle. Dried Thai chiles are ground into the chile flakes used in Thai cooking (prik pon). For curry paste: pound fresh Thai chiles with garlic, shallots, lemongrass, galangal, kaffir lime zest, and other aromatics in a mortar. A few Thai chile plants provide enough peppers for a household's Thai cooking year-round.
Verified against: kasetsart-u, rhs-uk, u-florida-ifas. Last reviewed 2026-05-15.