How to Grow Chilli Peppers


How to Grow Chilli Peppers

A far wider range of Chilli Peppers is available as seeds than as produce in the shops. In fact there are thousands of chilli varieties to grow, in different colours, shapes, sizes,  levels of heat and unique flavours!


Chilli peppers are not hard to grow from seed but need a very long time to mature. It is therefore best to start sowing them early indoors or in your Harvst S-Series – late winter is generally a good time. Smaller varieties can be grown till maturity in your S-Series whilst larger plants can be moved to a sunny, sheltered and warm position outside, when the night temperatures are minimum 10-15°C.

Fill a pot, tray or multi-cell tray with peat-free compost and water it. Sow the seeds at least 2cm apart and cover lightly with compost or vermiculite – unless it says on the seed packet that they need light to germinate. Water again carefully. Putting a plastic dome or cling film on top can help germination but make sure it has air holes for ventilation! Keep the soil evenly moist until the seeds germinate because if they dry out, it’s likely they will not germinate at all. Having said that, be careful not to overwater! 

Peppers ideally need 18-26°C to germinate well and normally appear within 7- 14 days, but some varieties can take longer to germinate. Once the seedlings appear, remove the plastic and place in a bright location with 12-16hrs of light. 18°C is an ideal growing temperature.

Plant care   

Transplant the seedlings to their individual 7-9cm pots when at least one set of true leaves has formed. Repot them into slightly larger pots when the roots start to stick out at the bottom, aiming for a 20-30cm pot as the final one. 

You can keep the pot in your mini-greenhouse or put it outside in early summer when the night temperatures are above 10°C. To acclimatise the plants to outdoor conditions, lift them outside in a sheltered, lightly shaded spot during the day, and put them back in at night. Gradually increase the time outside. Do this for about two weeks before leaving them out all the time. 

Try to keep the pots evenly watered, and feed every 10-14 days with a balanced liquid fertiliser, changing to a high-potash feed every 7-10 days once the first fruits start to set. 

When growing in your S-Series, pollinators may struggle to get to your plants so they will need help to pollinate properly. Stroke the inside of the flowers with a small paintbrush to pass pollen from one flower to another. Mist the foliage regularly when growing indoors or under cover with tepid water – this will discourage red spider mites and to help flower set. 


The approximate time between sowing and harvest is 18-24 weeks depending on the variety. Harvest when the fruit is the colour that particular variety is supposed to be. However, if you want them mild, pick when green. Wash your hands after harvesting and be careful not to touch your eyes until you do so! 

Watch out! 

The biggest problem tends to be red spider mites. Avoid them by regularly misting the plants, especially if grown under cover. Whitefly can also be a problem which can be treated with an organic soap spray. Blossom end rot is a result of erratic watering but is not as common as on tomatoes. Botrytis, or grey mould can be a problem in a greenhouse. Ensure good ventilation and remove any dead plant material promptly to prevent it. 

Pro Tip

Make sure to research the heat of your chillies before buying the seeds. The heat can vary a lot for the same variety depending on its growing conditions. If you happen to burn your mouth while eating chillies, try a glass of milk or a spoonful of sugar, rather than water. 

Nerdy facts

In 1912, the Scoville scale was invented to measure a chilli’s heat. The more water needed to dilute a chilli solution before a human taster can no longer detect the chilli, determines the number of Scovilles. A score of around 3,000 Scovilles is considered hot, but some like ‘Carolina Reaper’ goes up to the two million mark. Luckily the testing is done by machines nowadays!

Recommended Varieties

As previously mentioned there are thousands of chilli varieties. Here are a few smaller varieties that will comfortably grow in your Harvst mini greenhouse. ‘Thai Hot’ has lots of small but very hot fruits on a compact plant.

‘Pretty Purple’ is a small plant reaching only 30cm with small, round fruits that start off purple and ripen to yellow and orange and finally red. 

Chilli ‘Apache’ is a good variety for outdoors or in your Sprout. The green fruits mature to red and are medium heat.

Chilli ‘Firecracker’ is a very attractive plant, reaching only 40cm high with cone-shaped fruit in a rainbow of colours from purple, through yellow and orange, to red

Chilly Chilli’ is a very small plant reaching only 20cm high. It has very mild fruit reaching 6cm.