Aphids
Aphids or greenfly can be a problem for chilli plants as they will suck the sap of the new shoots as the plant develops. Squash them as soon as you see them appear. If the problem persists, spray with SB Plant Invigorator.
Whitefly
As a greenhouse plant, chillies can be susceptible to the sap sucking glasshouse whitefly. This has the double disadvantage of causing sooty moulds which grow on the resulting honeydew excreted by the insects. Good glasshouse hygiene is key to prevent the whitefly overwintering, and biological controls (Encarsia wasps) work well to control numbers before they build up to a major infestation.
Grey mould
Grey mould on chilli plants is caused by moist warm conditions, so make sure you have plenty of ventilation in the greenhouse. Tidy up any affected leaves and fruit to avoid the spores from spreading and clean the greenhouse well each winter.
Yellowing of leaves on chillies
This will be a sign of stress due to nutrient or water deficiency. As you are most likely to be growing your chillies in a pot you will need to attend to their every need – they cannot go looking for it in the garden soil. A weekly liquid feed is essential once the nutrients in the compost have all been used up (after around a month). This practice should also ensure that the plant is getting enough to drink, but always check the weight of the pot before you water, as their need for moisture is very dependent on weather conditions.
Chilli plant leaves curling
Leaves will curl if a chilli is in need of water or indeed it has been overwatered, so make sure you get it just right. Insect damage might also be a cause so check underneath the leaves for aphids or whitefly. Some insects will introduce a virus which can cause leaf curl so isolate the affected plant for a while to avoid transmission.
Chilli plant not flowering
This is usually caused by either low temperatures or over feeding with nitrogen-based fertiliser. Give just enough to keep the leaves looking healthy without getting too luxuriant. As soon as you see the buds forming switch to a potash liquid feed (tomato food) to ensure the plant switches to fruit production.
Chilli plant flowering but not fruiting
There can be several reasons for this. Insufficient warmth might be one, if the temperature is dropping below 15 degrees at night, and not reaching 25 during the day. Chillies are generally self-fertile, but if there is very little air movement in the glasshouse they might struggle, so you can help by brushing gently over the flowers with a feather duster, or misting with water during hot dry conditions.
Chilli plant flowers falling off
This is often caused by too much heat, so it may be that your greenhouse is reaching more than 35 degrees and could do with some shading at the height of summer.
Chilli plant wilting
This could either be lack of water, or possibly root damage, caused by vine weevils in the pot. If the plant does not revive after a drink turn it out of its pot and check for large white grubs on the roots – these will need to be destroyed and the compost thrown away. Scrub out the pot in case of eggs and then replant the chilli in fresh compost.
What is eating my chilli plant leaves?
There are very few animals that would attack a chilli plant, so it is most likely insects such as the aphids above, or slugs and snails will have a go at young seedlings before they get their spicy defences fully engaged.
