Chili Peppers: Germination and Pre-cultivation

There are hundreds of different varieties of chili peppers in the world that differ in heat, shape, color and size. What all types of chili have in common, however, is that they are heat-loving plants with a relatively long growing cycle. If you want to grow them outdoors in our conditions, it is therefore important to start early and raise them indoors first. We will show you how!

Many of us love chili peppers for their heat. Heat is measured on the so-called Scoville scale, named after the American chemist Wilbur L. Scoville. While mildly hot jalapeños measure about 2,500–8,000 SHU, the recently bred record holder “Pepper X” reaches a staggering 3,180,000 SHU, enough that eating it has caused anaphylactic shock in some individuals. The burning sensation is caused by a chemical called capsaicin, which stimulates nerve endings in the mouth and is thought by some to have medicinal effects. Capsaicin content depends mainly on the cultivar (bred variety), but also on the plant’s age and growing conditions.

How to choose the right chili variety for growing

Chili can be grown in many ways: outdoors in a pot or in the ground, in a greenhouse, or indoors under artificial lighting or hydroponically. The chosen cultivation technique has the biggest influence on selecting the right chili variety for your garden. Different chili varieties differ not only in taste, appearance and heat, but also in length of the growing cycle. Some varieties (often the hottest) take so long to flower and ripen that they would have little chance to mature outdoors here. Varieties with long flowering times are therefore better grown indoors under artificial lighting. Below we list several popular chili types with regard to flowering time and the suitable cultivation method.

• Jalapeño is a variety of chili native to Mexico; it won’t knock your socks off with heat, but it’s easy to grow and is great for cooking—use it in sauces, salads, nachos, or pickle it in a sweet-and-sour brine or smoke it (chipotle). Plants reach about 1 meter in height and do well in full sun or in a greenhouse. Jalapeño has a relatively short flowering and ripening period (80–125 days) and is suitable for outdoor growing.

• Bhut Jolokia, also known as Ghost Pepper or Naga Jolokia, is one of the hottest peppers in the world. Its heat, which can last for hours after eating, is accompanied by distinct apricot and apple notes. The fruits change color from bright green to deep red as they ripen, though some types can have white, orange or chocolate-colored fruits. Bhut Jolokia is a bit more demanding to grow and requires a constant temperature of around 24–28 °C for germination. Plants reach about 1.2 meters and have a longer ripening time. This variety is suitable for outdoor, greenhouse and indoor growing.

• Trinidad Moruga Scorpion is an extremely hot pepper from Trinidad. It occurs in two cultivars, one with bright red and the other with yellow fruits. Both varieties have the characteristic stinger-like tip and a very thin skin under which a huge load of capsaicin is stored, reaching up to around 2 million SHU. This cultivar is better suited to experienced growers. Seed germination can be challenging and you will likely need a heating mat. Patience is required for ripening, which can take more than 160 days. Trinidad Scorpion is suitable only for indoor growing under artificial lighting.

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How to germinate chili seeds

Best time for germinating chili seeds for outdoor growing is from January to March. The earlier you start, the better. Your seedlings will gain a head start before the sun really comes out. Before you begin, make sure you have all the necessary equipment prepared.

• Chili seeds
• Seed tray or seedling pots
• Sowing substrate (or seedling tablets, seedling cubes, rockwool)
• Propagator (plastic cloche)
• Sprayer
• Other equipment (heating mat, LED grow light, grow tent)

Germinating chili seeds should always be done indoors, as they need sufficient warmth. You can place the germinating seeds on a windowsill where they get sun, or use a heating mat to provide a constant temperature. This is especially important for more demanding exotic varieties.

• Fill the tray or germination container to the top with sowing substrate.
• Moisten the substrate using a spray bottle.
• Sprinkle a few seeds on the surface of the substrate and cover them with a layer of substrate or vermiculite. If you use jiffy or seedling cubes, place the seeds in the prepared hole.
• Place the germination container inside a plastic propagator and put it in a warm spot with plenty of light.
• Maintain a constant temperature. For chinense varieties 24–32 °C, for annum varieties 10–24 °C.
• Seeds should germinate within 3–10 days depending on the variety and seed age.
• Keep the substrate moist but not waterlogged the entire time.

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How to plant and pre-grow chili seedlings

You can transplant germinated seeds once they have grown and the first two small leaves have emerged. For pre-growing, it’s better to plant the germinated seedlings first into a small pot and only move them to the bed or a larger container when the seedlings have grown. This helps develop a robust root system.

Water the seedlings regularly during pre-growing, but be careful not to overwater the substrate or let the roots sit in water. From the second week you can start feeding the plants with a weak growth fertiliser or a fertiliser designed for chili peppers.

Raise the seedlings either on a windowsill with enough sun or under artificial lighting in a grow box. Whichever method you choose, make sure the plants receive at least 12 hours of light. Lack of light or too low intensity will slow plant development. Under the right conditions, chili seedlings should grow enough within a month to be moved into a larger pot and transferred outside or under stronger grow lights.

If the idea of a garden full of chili intrigued you and you want to learn more about growing them, read our article on growing chili.