Peppers and chillis are expensive when bought in the shops so growing your own is an economical exercise which also brings great pleasure. They are tropical plants and therefore appreciate warm moist conditions. Although they can be grown outside in some parts of the UK they always mature quicker and produce a better crop when grown in the greenhouse. Slightly exotic they may be, but with a greenhouse they are an easy crop to grow.
Peppers need a long growing season so the earlier you get started the better your chance of producing good, ripe fruit. Get the seeds sown in February on a heating mat if you can. They can take up to 2 weeks to germinate. Sow seeds at 20 degrees celsius in pots of compost or module trays. Transfer in to 9cm pots when the seedlings are large enough to handle. Pot up again to a 30cm pot when the plants look like they’ve outgrown the previous pot.
When the plants reach a height of 5 -8cm / 2 - 3in they should be transferred to larger 20 - 23cm / 8 - 9in pots. Fill in with normal potting compost and water well. The potted up plants should be set at the same depth in the soil as they were in the smaller pots.
Peppers and chillis can also be grown in grow bags, just like tomatoes. Simply transfer them from the small pots into the grow bags.
Some peppers and chillis can grow up to 1.5m / 5ft (consult the seed packet) in which case they will require some support. This is best put in place at the time of potting up. Use a bamboo cane or two per plant and tie it into the canes with string as the plants grow.
The compost should be kept moist bit not water-logged. Once the pepper / chilli plants are potted up (see section above) feed with a weak liquid general purpose fertiliser once a week.
When the fruits start to form, feed with a liquid tomato fertiliser once a week for the rest of the season.
Peppers and chillis can withstand high temperatures reasonably well but it is likely that you will have other plants in the greenhouse which will require the windows to be opened when the inside temperature reaches 22°C / 72°F. This will be fine for peppers and chillis.
To encourage the fruits to develop fully in the growing season, thin the fruits out so there are only around 8 per plant. The time to harvest the fruit depends on your preferences. The fruits will go from green through to bright red, harvest them when they are fully grown and at the colour you prefer. Harvesting them when they are green will encourage the remaining fruits to ripen quicker. Cut the fruits off with a knife rather than pulling them off which may damage the plant.