How to Grow Chilli Peppers

7 August 2009, written by Jeremy Dore

Hot chilli peppers are something I have always had mixed success with. Usually I grow plenty of sweet peppers with a few chilli plants on the side. Yet despite trying several varieties over the past few years I have rarely managed to get much heat out of home grown peppers. Growing here in the UK does mean they take longer to ripen and need extra care and attention. Still, the results were disappointing – plenty of peppers but where was the heat?

To diagnose this lack of heat in peppers I contacted our expert, Barbara Pleasant, who says that cool, damp weather can take the heat out of some chilli peppers and there can be a lot of variation, even in seeds from the same seed packet. This would certainly account for my previous experience.

Peppers can also cross-pollinate with each other very easily as insects move between them. Many people believe that cross pollination between sweet and hot peppers is what causes lack of heat. However the genes from each plant will only be mixed in the seeds inside the peppers, affecting the next generation - the peppers themselves will stay true to the original plant. So, this year I set out to grow the two types of peppers in dryer, hotter conditions from a different supplier of seed and, hey presto, I have chilli peppers with fiery heat!

If there is one tip you need to know about growing peppers it is this: they hate getting cold. Most of the important growing advice stems from this one fact:

Peppers should be started off with indoor warmth, away from draughts. I use a heated propagator at about 18 °C (64 °F) and sow three or four into 3 inch pots of seed compost. This can be done in late winter or very early spring as they take time to germinate and grow.
After 4 – 6 weeks of good growth they will need re-potting into individual pots. Because peppers have quite small root systems they don’t like a lot of cold compost around them, so I usually wait until they are at least 5cm (2 inches) tall. After another 4-6 weeks I transplant them into 6-8 inch pots that will become their final homes, just adding a layer of extra compost later on.
Once the weather warms up they can be gradually introduced to the outside temperatures. To keep them happy, I always take some time to gradually harden them off.
In cooler climates such as the UK I find it necessary to grow peppers in the shelter and warmth of a greenhouse. Without this they tend to just sit in the ground doing very little and certainly not bothering to produce fruit.
Even within a greenhouse the peppers do much better when raised up on staging. Down at ground level they succumb to cold air and are easily crowded out by other plants. My best peppers always come from pot-grown plants in the prime sunny spots on my greenhouse bench.
To get your peppers to ripen and produce a good crop, see our recent article on The Long Wait for Ripe Peppers. There Barbara Pleasant reveals the vital tips that will get your plants pollinated, your peppers ripening and a bumper crop from a few plants.

Hot peppers come in a whole range of varieties: Cayenne, Anaheim, Ancho and Jalapeno types to name but a few. Even within these types there are huge variations on how hot the peppers will be, so unless you are partial to burn-your-mouth sensations it is wise to consult seed catalogues very carefully before choosing varieties. I have had particular success with a standard ‘Hot Cayenne’ variety this year but many people also recommend ‘Hungarian Hot Wax’ and ‘Apache’.

Each pepper will also accumulate heat as it matures – picked green they will be much milder, turning hotter as they ripen to a deep red. The hottest part of the chilli is the white flesh that attaches the seeds to the inside of the pepper, which can be removed if you want to limit the heat. The chemical which gives the chilli pepper its heat is called capsaicin, and because this is an irritant it is important to either use gloves when handling hot chillies or thoroughly wash hand afterwards. Anyone who has inadvertently touched their eyes after handling a pepper will know why (which is probably why an extract of capsaicin is the main component of pepper sprays used by police forces).

Peppers can be eaten fresh or preserved but this does vary by type. The cayenne types are the best for drying – just hang the whole plant upside down when the peppers are fully mature in a dry, frost-free place for several weeks. Once dry store them in an airtight container. Another great idea is to create fresh chilli oil but if doing so it is very important to follow these steps:

Wash containers thoroughly, or even better boil or bake them to sterilize them
Crushed dried chillies are best as they contain little moisture
Simmering the chillies in a pan of malt vinegar for 10 minutes will help acidify them so that they can be stored for longer
Adding the chillies to hot (but not over-heated) oil and then letting them infuse for some time will transfer much of the heat to the oil. Remember that pouring hot oil into containers is a potential hazard as it may cause them to crack, so allow it to cool first.

[When preserving in oil there is a small risk of a very serious soil-borne disease called botulism which thrives in conditions in which foods with a pH above 4.6 are stored where there is no oxygen, such as under oil. This is why the above method acidifies the chillies in vinegar and uses dried chillies. Refrigerating the finished product is also a sensible precaution and you should apply the same principles to anything else you add to the oil.]

Once you start growing chilli peppers it is easy to get hooked. There are so many different types, colours and flavours to sample and it is easy to produce a bumper crop of high-value peppers for very little effort. Some people grow special varieties for grinding their own spices, such as the Anchos used for chilli powder or the Paprika types to make spice of the same name. Others grow them for the challenge of exotic peppers ranging from bright yellows to deep purples. Whatever you choose, be prepared for some mouth-tingling experiences and a great sense of achievement.