Serrano Chilli

Capsicum annuum (nightshade)

Also known as: Serrano Pepper

A traditional Mexican chilli from the mountainous regions of Puebla and Hidalgo, its name simply meaning "from the mountains." Slim, smooth, thick-walled pods ripen from glossy deep green to bright red, staying crisp and crunchy whether eaten fresh or cooked. A step up from the jalapeño in heat but every bit as versatile, with a bright, clean flavour that's earned it a place as Mexico's second most-used chilli after the jalapeño — essential in fresh salsas, pico de gallo, and pickling. Medium-hot heat of around 10,000–23,000 Scoville Heat Units.

Days to harvest 75–85 days
Fruit size 5–10cm, slim, thick-walled
Sowing depth 5mm
Germination 8–18 days at 24–29°C
Spacing 45–60cm apart
Aspect Full sun, well-drained soil
Frost tolerance Frost sensitive — needs reliably warm nights

Growing notes

Choose a full-sun spot with fertile, well-drained soil. Vigorous, branching plants reward regular picking with heavy, ongoing production. Suits 20-30L pots.

Soil preparation: Well-drained soil with plenty of compost worked in.

Support: Staking or a small cage recommended once plants mature and carry a full crop.

Watering & feeding: Water deeply and consistently, avoiding waterlogging. Feed with a balanced fertiliser once flowering begins, avoiding excess nitrogen which favours leaves over fruit.

Harvest: Pick once pods are firm, full-sized, and glossy — usually green, though left to ripen red brings extra sweetness and complexity. Use pruners or pinch carefully to avoid snapping branches.

Timing: Expect first harvest around 75–85 days after transplanting, with frequent picking encouraging continued flowering and fruit set.

Key features

  • Open-pollinated Mexican heirloom
  • Medium-hot heat — 10,000–23,000 Scoville Heat Units
  • Slim, thick-walled pods, crisp and crunchy
  • Ripens from deep green to bright red
  • Bright, clean, slightly smoky flavour
  • Essential for fresh salsas and pico de gallo

Short season tips

Best started indoors on heat mats — this variety needs 24–29°C soil to germinate, and germination can be erratic if planting depth isn't consistent. Sow 8–10 weeks before the last frost or purchase as 6–8-week-old seedlings. Transplant into the garden only once soil temperature has reliably warmed to at least 15°C and nights stay above 13°C. Avoid disturbing roots when transplanting — chillies resent being moved and stall easily.

  • Spring
  • Summer

Tender perennial — most often grown as an annual

  • Basil (particularly good for capsicums and chillies) Marigolds Onion Carrots
  • Other nightshades (tomatoes, eggplants, potatoes) Fennel

Native to the mountainous regions of Puebla and Hidalgo in Mexico, where cool nights and warm days produce thick-walled, flavourful chillies. Long selected and refined by local growers over generations, it remains a cornerstone of Mexican cuisine and is now Mexico's largest chilli export, grown across more than 14,000 hectares primarily for fresh use.