There are a great many misconceptions with chilli plants, to start this guide off I will try to cover a few of these, for those who want to jump ahead, do feel free.
Whilst there are a large number of chilli experts, many people instead know chillies as a hot red blob people put in curries. That is pretty much the furthest thing from the truth. Chillies come in a wide spectrum of colour and taste, from green to purple to black or brown and from smoky to fruity, citrus or hot burning agony.
Chilli plants are quite possible to grow outdoors in most parts of the UK, however the hotter the chilli, generally the more heat required to produce them and the longer it takes to germinate them. The best results will be given if you have a sheltered sunny position but we will also cover how to grow them indoors if needed.
The most important thing to bear in mind is start early.
Before starting germination, you should know what sort of chilli you have, as there is a wide variance of light and heat requirements for germination then knowing what you have will help you get a strong plant. The species also gives you a guide as to what can be overwintered and how easily they germinate.
Capsicum annuum: Despite the name, the annual chill is actually perennial if looked after well, They are derived from north America and therefore they benefit from a hot but slightly dry environment. Whilst this doesn't mean desiccated, they will cope with poor watering better than some other chillies and they develop stronger taste in such situations.
Capsicum baccatum: This species is best known for Aji chillies, often described as semi-domesticated, they produce very few seeds and have a low germination rate (60-80%), however this is more than offset with the high vigour and superb taste these plants provide. Of particular note is Lemon Drop and Dedo De Mocha, the first one being lemon scented and flavoured, with the second having a low heat which reveals the deep smoky complex taste characteristic of the Aji group.
Capsicum chinense: There has been some debate about chinense and if it is actually the same species as annum, they share certain characteristics however when crossing between the two species, there is a loss of fertility compared to interspecies crossing. The epithet chinense is like annuum, completely wrong as all chillies derive from the new world. They germinate readily and contain some of the hottest chilli cultivars such as habanero and Trinidad scorpions.
Capsicum pubescens: Pubescens means hairy, making this the hairy chilli although the other common name is the tree chilli. This species is very rare and distinctly different to other cultivars. The most important difference, and where it gets the tree chilli name, is that it reaches maturity quickly and can live for over 15 years and tolerate the cold much better than other cultivars, making them superb for overwintering. There are reports that the plants can reach four meters or more by the time they reach old age and they can be extremely prolific. The other differences are they have slightly hairy leaves, purple flowers and black seeds!
Growing chillies from seed is the traditional, most common way to start a plant out, as the seeds are small, they should not be planted too deeply, ideally just a surface covering to preserve moisture. Although if you want to do it in bulk, it is quite possible to sow into seed trays or half trays (here we do about 40 seeds to a half tray to fit in our propagators) you will generally get better results sowing into plugs or cell inserts as you can leave them in until they have formed their second leaf sets. If you do it in half trays, you may get better results by re-potting them earlier so you don't damage the roots of other seedlings.
Initially chillies only require heat and moisture to germinate, this this varies between cultivars always try to look up the species before germination, If you are growing numerous species then just try to keep the heat constant, such as in a propagator. An ideal seed mix would be 40% JI Seed, 40% multi-purpose and 20% pearlite with a covering of fine vermiculite, however for most non-specialist chilli seeds, multi-purpose compost should be perfectly fine. Try to keep them slightly moist throughout germination (and I don't mean drowned!).
With the first sign of germination then move the plants to somewhere slightly cooler and well lit. The best time for sowing seed is mid-late January if you have a heated propagator.
After the chilli plants have germinated then you should see two leaves emerge, these are the cotyledons or seed leaves. The pair after this are the first "true" leaves and when they are about 1cm long, this is the stage you will want to re-pot them if you planted them singly. Handle them gently and by the leaves, supporting them from the roots with a label. When pricking out seeds you should always lift from below the root zone with a pencil or label. Although the seedlings are tougher than you would think, its still not a good idea to recklessly damage them. For the first pot use a liner (10cm) and after it has developed a root system big enough to reach the drainage holes in the bottom of the pot, re-pot it into a 3L.
After a few weeks from re-potting you can start feeding it, there is a lot of conflicting information on what to give chilli plants, however it boils down to not too much nitrogen, tomato food or vitax q4 is ideal. Keep re-potting it until its reached the size you want and as the weather warms up then you can move it outside if you want, into a sheltered place overnight, just be sure to acclimatise it as time goes on.
At some point (time determined by the cultivar), if you haven't killed it by following my instructions, you should start to see flowers appearing. If the plant is outside then you don't need to do much as bees will readily pollinate them, the only thing to watch for is that the plant doesn't dry out to the point of blossom drop (don't confuse this with pollinated flowers dropping as the chilli will push the flowers off), A little heat or dryness will stress the plant slightly and as a result increase the heat of the chilli fruits.
If the chilli is grown under cover or you are using the seed saving method below, shake the plant slightly and this will help release the pollen and increase fruit set.
Notably unlike tomatoes, you should not try to encourage overly strong root growth, even the earliest chilli plants are slower than tomatoes and they can struggle to ripen properly or have reduced yields if they spend too much time developing roots.
You can harvest chillies at almost any time after the fruit has reached its full size. Over time the fruit will ripen and change colours, this will also change the taste characteristic which is in most cases mild at first before developing heat later. Again the colour and ideal time to pick depends on the cultivar you are growing. The best way to harvest is with a sharp craft knife or secateurs and cut above the fruit with a clean cut. You can then use the fruit in a number of ways, there are instructions on drying and seed saving below.
Congratulations! But this is not the end, there is so much more you can do with this plant, even after taking fruit!
Seed saving is incredibly worthwhile with chillies and it can be selectively done to improve a certain cultivars suitability to your growing environs or to cross two chillies you particularly like. If you want to create your own cultivars, look to the breeding page (not yet written) for information on stabilising and finding which species are capable of crossing.
The first thing you will want to consider is what you want the seed to become, if you don't mind, then just let the local insects pollinate the flowers and skip the next two paragraphs, otherwise you will need to isolate what fertilises the plant.
To do that you have two options, if there are no other chillies nearby and its in a house or greenhouse you can be fairly certain it is not cross pollinated, otherwise there is a trick you can do to ensure purity. You will need to get some close weave net or nylon (think women's tights), some thread and a shoelace. Cut a rectangle of nylon, not too big or small and lie the shoelace on the top edge, fold the nylon over it and stitch it in so that it can be tightened, much like a coat hood. Then stitch it together to form a bag.
With that bag you can now wait for a flower that has not opened yet and put the bag around it, meaning when it opens there is no way for a pollinating insect to pollinate it. After the flower opens then either shake to self pollinate or cross with a paintbrush, let the chilli start to form and push the flower off then remove the bag (but remember to mark the flower stem) and you have a tailor made fruit.
The next step is the actual seed saving, Seed can only be saved from fully ripe plants, so don't try it too early. One important thing to note, that many people miss is that air dried seed is only dormant meaning it is still metabolising and it will sweat, burn through energy and have all sorts of problems such as rotting and very low germination/lifespan!
The better method is to rice dry the seed. for that then put some rice on a baking tray and cook it for 45 mins on medium heat, you will want at least twice as much as you have seed. Afterwards pour it into a jam jar with a lid or cover to make sure the air inside remains dry. This will suck the moisture out of the air and create a very dry area for the seed to rest in. Let the rice cool (so you don't destroy the seed) and put your seed in a nylon or similar bag (again think ladies tights with a rubber band) on top of the rice, then put the lid back on. After a fortnight, your seed should be ready for storage and be absolutely bone dry.
There are three main ways to dry chillies, air drying (the longest), Sun drying and Oven drying (the quickest)
For simple air drying, all you need is a warm and dry well ventilated room. Simply thread the stems of the chillies together and hang them so that air can pass around. This can take up to three weeks, and whilst the easiest way to do mass chillies or whole chillies in a cool damp environment normally results in them moulding. This is best done with small chillies.
For sun drying you need at a minimum three days of hot sun. Split the chillies into half’s (or more for larger fruits) and place on a metal tray in a hot spot, turn them occasionally and at night just cover them slightly to avoid insects and such causing problems. Whilst this is a natural easy way to dry them, it also takes a consistent period of hot weather which can be hard to come by in this country and especially so if the chillies are late.
The quickest way to dry chillies (other than a dehydrator) is to oven dry. For this simply place the chillies on a clean non-stick tray and bake in a fan oven for between 6-8 hours at 40 degrees. The chillies should be halved or more depending on the size, just watch out for heat damage.
Regardless of the method when they and can be broken apart easily with your fingers, they are done and can be stored for use in cooking.
Overwintering can be done with most chillies (although it is easier with some) and unless they are in the ground or you do not physically have enough room, they should be. Chillies that are overwintered produce fruit earlier, produce much more of it and put on extra growth. Both C. baccatum and C. pubescens are superb for keeping however C. anniuum is less easy to maintain.
As the temperature starts to drop and light levels fall, the chilli will enter a hibernation phase, effectively slowing down growth and dropping leaves to reduce its requirements. As a result, you want to keep the chilli in a well lit environment that is warm so watch out for breezes. Do remember to water it but only sparingly as their growth is slowed down significantly
To make it easier on the plant it is recommended you remove any lingering pods and prune heavily so it dose not try to maintain fruit or leaves and therefore deplete its resources. It is also an ideal time to re-pot a chilli and gently prune its roots as the plant is becoming dormant and this will cause much less shock this time of year.
Prune off any brown material as that has started to die back to the main stem, prune strongly as one year old chillies are extremely vigorous and it will recover any damage done quickly.
Cuttings are a superb way to propagate chilli plants for a number of reasons. Firstly, speed. In much the same way chillies are quicker from overwintering, a cutting can have established roots and started putting on roots before some chilli seed has even germinated! This is particularly useful with some of the hard to propagate cultivars. In addition to this, the plants will be genetic clones of the mother plant which is the only way to reliably propagate F1 cultivars and a certain way to avoid accidentally crossing with another plant.
To take cuttings, take a soft green shoot with ideally two nodes (where the leaves come out) although one is use-able and remove the bottom leaves. The cut should be clean to avoid damage and infection and just below the node as that is where most of the hormones are. If you use rooting powder, just dip it in and tap to remove the excess and push into damp soil. Ideally you would put a bag over the top to retain moisture. Bottom heat will help speed up the cutting drastically!
My personal method is a bit different and is extremely quick if you have a source of strong heat. Rather than using a pot of soil, use a cube cut from oasis foam about 1cm wide and 2.5cm deep. Pre-poke a hole in that is wide enough for the chilli stem and soak fully in water. Then take the cutting and stand in a tray with 1cm of water. As there is constant water the cutting will not dry out and root quickly even in full sun, however there must be enough heat to stimulate growth.
This is an Aji chilli with a yellow coloration and a lemon-citrus taste and scent. Slightly hotter than a Jalapeño it is a fantastic vigorous plant
This is a specially selected Jalapeño that ripens early and is well suited to the UK climate where Jalapeños often fail
Alberto's Locoto Rocoto
This is a C. pubescens so it is extremely rare and can be overwintered for a long time. Although it is a hot tasting chilli it has few of the side effects.
This is a hot cherry shaped chilli that is at its best red. It is quite aromatic and is a compact bush.
Dedo De Mocha
This is another Aij chilli but without the traditional hotness. It has a superb smoky complex taste and is fantastic barbecued.
Ohnivek is a Czech cultivar that has been developed in a special breeding program. Its chillies are mild when green but extremely hot when red and can be as long as a foot given good conditions!
Grey feathery chains of spores appear that act like dust if touched
These are poor pathogens and only really affect chillies that are stressed, wounded or are in constant contact with other infected material.
Can try to prune out minor infections but sterilize after every cut. Otherwise remove and destroy plant.
Decrease humidity and increase airflow. Don't over water.
This affects seedlings, the stem becomes very thin and rotted, the seed collapses
Despite the general hysteria, this is only a problem when plants are over watered. If it starts appearing, you can treat it with copper but it is best to be sparing with water to start with.
Blossom End Rot
The bottom end of the chilli has a blackish patch, soft or hard on the fruit.
This is linked to a calcium deficiency and poor watering, remove damaged fruit and try to keep watering constant.
Flowers fall before fertilisation
Firstly check to make sure the flowers arent being pushed off by growing fruits. If they are falling without fruits appearing then try increasing the watering slightly. If in an enclosed area, shake the plant to aid in self pollination.
Yellowing flower stalks can mean a number of things, low nutrients, lack of water or un-pollinated.
Holes in fruit
Holes in the fruit that sometimes cause it to part ripen or dry fruit up.
This can be caused by a number of pests but most often slugs or earwigs.