Seedlings and young plants can be planted out as soon as they are well established and have roots showing. The appearance of the second true leaves is an ideal sign that plants are ready to be potted out. Plant them in moist compost in small pots (8-10 cm) and make sure that they are well located in the medium so that the bare stem is well covered in compost right up to the first set of leaves.
This will allow the development of new root structures up the stem and add strength to the plant. Depending on the cultivar you may have to pot up the plant again in a few weeks time. Do so when the roots are clearly coming out of the pot.
Once the risk of frost passes you can put the plants outside. Initially you might want to harden them off by placing them outside for just a few hours a day. You can pot them up in big pots or directly into the soil but both chilli and pepper plants need a well drained substrate.
Light and temperature
Chilli plants require much sunlight. In terms of temperature, chilli plants can be treated as half hardy annuals. The temperature requirements may vary according to the cultivar with a minimum 12°C.
Watering and feeding
Water as needed to maintain the growing medium is just moist but not wet. Never let the soil dry out completely. Larger pots require less frequent watering than small pots, pots in full sun light will need more watering than pots that are in light shade for part of the day. A small plant in full sun may need watering every day. When you water, make sure you water deeply so that the water gets down to the roots where the plants need it, rather than just wetting the top where it will evaporate away. When in their vegetative stage, chillies will benefit from feeding every week, ideally with a specialist feed such as Chilli Focus. When flowers appear the strength of the feed can be increased as well as the frequency.
Pinch out the growing tips occasionally to encourage them to bush out. Plants may need some support from branches pushed in around them or they can be tied to a cane.
Flowering and fruiting
As the plants grow, small, normally white flowers will begin to bloom. The flowers will begin dying after a few weeks and chillies will form. Soon after, the flower's petals will drop off as the green middle starts swelling, which is the chilli pepper growing. The plant will continue producing fruit into the autumn and perhaps beyond under favourable temperature and conditions. Chillies and peppers can be harvested green or when in colour.
Pests and diseases
Chillies growing in this country are largely trouble free. In very warm, dry conditions they may be attacked by red spider mite (you'll see very fine webbing and tiny little mites on the underside of leaves). Sometimes aphids can be a problem especially during the early stages of growth. The answer for both of these is to use an organic fatty-acid type spray such as SB Plant Invigorator, which is suitable for use on food crops. This suffocates the pests without damaging the chillies.