Chilli Growing Glossary

Capsaicin

The compound in chillies that causes heat sensation, concentrated in the placenta (white pith) rather than the flesh or seeds. The higher the capsaicin concentration, the higher the Scoville rating.

Capsicum annuum

The most common chilli species, encompassing jalapeño, cayenne, bell pepper, serrano, and many other everyday varieties. The species is highly variable — it includes both the mildest and some moderately hot chillies.

Capsicum chinense

The species containing the hottest chilli varieties — habanero, scotch bonnet, Carolina Reaper, and Trinidad Moruga Scorpion all belong here. Distinguished by a fruity aroma alongside the extreme heat.

Cotyledon

The first pair of leaves after germination, also called seed leaves. These are not true leaves and look quite different from the mature foliage that follows. Once the first true leaves appear, the cotyledons gradually yellow and drop.

Damping off

Fungal disease that kills seedlings at or just below soil level, causing them to collapse suddenly. Caused by overwatering, poor drainage, or low airflow around seedlings. Prevention: water sparingly and ensure good ventilation.

F1 hybrid

First-generation cross between two stable parent lines. F1 plants tend to be vigorous, consistent, and high-yielding. However, seeds saved from F1 plants will not breed true — they will produce unpredictable offspring.

Hardening off

Gradually acclimatising indoor-raised seedlings to outdoor conditions over 7–14 days. Start with a few sheltered hours of outdoor exposure and increase daily. Skipping this step causes sunscorch, wilting, and setback.

Internode

The stem section between two leaf nodes. Long internodes indicate the plant is stretching toward inadequate light — a leggy plant with long internodes will be weaker and produce less. Provide more light to keep internodes short.

Open-pollinated (OP)

Varieties that breed true from saved seed. Plants grown from open-pollinated seed reliably produce the same variety, making them useful for seed saving. Unlike F1 hybrids, OP seed can be saved year after year.

Overwintering

Keeping chilli plants alive through winter indoors so they can grow again in spring. Second-year plants are significantly larger than new seedlings and begin fruiting much earlier in the season.

Pinching out

Removing the growing tip of the main stem just above a leaf node to encourage side branching. The plant produces two shoots from that node, creating a bushier shape with more fruiting sites. Can be repeated on side shoots.

Placenta

The white pith inside a chilli fruit where capsaicin is most concentrated. Seeds are attached to the placenta and absorb capsaicin through contact. Removing the placenta and seeds significantly reduces the heat of the fruit.

Scoville Heat Units (SHU)

The measure of capsaicin concentration in a chilli, named after pharmacist Wilbur Scoville. Bell peppers score 0 SHU; jalapeños typically reach 2,500–8,000 SHU; Carolina Reapers can exceed 2 million SHU.

Stratification

Cold treatment used to break seed dormancy by mimicking winter conditions. Not required for standard chilli seeds, but relevant if collecting seeds from wild Capsicum species or unusual botanical varieties.

Variegated

Leaf pattern showing patches of different colours, typically green and white or green and yellow. Can be a deliberate variety trait (some ornamental chillies are bred for variegated foliage) or a symptom of mosaic virus. Check for other disease symptoms to distinguish the two.