Growing Chilli Plants
Learn how to grow chilli plants from seeds from the experts. We were featured on the BBC Gardeners World programme during their 2006 chilli seed trial. To purchase chilli seeds go to the chilli seeds page.
In the UK, chilli seeds need to be sown early in the year and grown on in a greenhouse or poly-tunnel, although they can be grown outside in a sunny spot during the height of summer. Germination can be very variable between varieties and can take as much as five weeks, though the varieties we sell on our seed page should all germinate within 10-14 days, some sooner. To help you get going, we have listed some of the tricks and guidelines we use to give our chillies the best start possible and for growing-on in pots.
We recommend that you use soil-based seed and potting-on composts - chillies really appreciate good drainage. We recommend a 'John Innes loam based seed compost' for germination.
Warmth and Surface Watering
Germination speed and percentage is greatly improved by applying warmth to the seed compost. We use thermostatically-controlled heated propagators, but placing the seed pots/trays in a warm environment or on a simple heated tray will also work well. With the seed compost at 27-32°C (80-90°F), you should see good results. Seeds will still germinate down to 21°C (70°F) but germination will be slower and more erratic. If the temperature drifts towards 38°C (100°F) germination will be quick but there will be a lower success rate.
Try to use surface watering with a spray bottle rather than watering from the base, surface watering has less effect on the temperature of the compost. Don't over water, and certainly don't make them swim. Watering with a sprayer causes less impact.
When to Sow
We mainly sow seeds during February and March, but you can leave it later. There is a great variance in the number of days taken for a particular variety to reach maturity. Some can produce ripe fruit in 60 days from sowing and others take as long as 120 days.
Remember that varieties such as Habaneros take 100 or more days (3 1/2 months) from potting on to reach maturity. So these need to be started in good time or the fruit will never ripen.
Germination and pricking-out
We tend to sow seeds about 5mm deep and in small pots, with a number of seeds of the same variety in each pot. Keeping each variety in its own pot is a good idea because germination time varies greatly. As soon as the majority of the seeds in a pot have emerged and are showing two well formed leaves, and certainly before they become leggy, they should be transferred into 3 inch pots. Hold the seedlings by the leaves, and not the stems. Note that some seedlings may need a little gentle help getting free of the seed pod. If you have the propagator space you can sow directly into 3 inch pots.
At this stage they should be moved to a site where they will get plenty of sunlight; ideally to a heated greenhouse or warm conservatory. Continue to keep them warm, moist and well ventilated. They can stay in a 3 inch pot until they are 3 to 6 inches high.
When the plants have about 5 pairs of leaves they should be potted-on into larger pots. We grow most of our plants in the ground and this is a possibility if you have a polytunnel or open soil in your greenhouse. Otherwise pot-on into 9 to 12 inch pots depending on the variety. You can use smaller pots for compact ornamental varieties. As the summer sun intensifies, you may need to provide some shade, for example, lining your greenhouse or painting with greenhouse paint.
Try to keep the plants below 36°C, be careful not to feed them a lot of nitrogen (they will grow big, but can forget to set fruit) and don't let them dry out; that should help prevent blossom-drop and pod-drop. Larger varieties may need support with a cane. Ornamental varieties can be moved to a bright position in the house or to a patio once they are well established. If your flowers are dropping off there could be a number of causes. If they are outside it is probably cold windy weather. If they are indoors it could be lack of humidity, in which case give them a mist spray. Lack of feed may also reduce flower production.
Different varieties are picked at different stages of their development. Fruits that start yellow or green generally ripen to red, though green chillies will sometimes ripen to orange or yellow, it all depends on the variety. Usually, and regardless of the colour, once they have filled out and become firm crisp and glossy they can be picked. Experiment by picking one to see if it has all it's heat and flavour. The sooner you pick the more the plant will produce so even if you don't need them at the time you should pick them and keep them in the freezer until you do.
Most chilli plants can be treated as perennial house plants, but will need some pruning in the winter. Some varieties are better suited than others, smaller hot varieties like Serrano and Twilight, and Prairie Fire do better than the bigger fleshy plants such as Poblano and Anaheim.
Have fun and feel free to email us at: [email protected]
Current customer FAQs and our Answers
Q: What is the best time of year to start sowing in the UK?
A: March usually works out best for sowing chilli seeds. You can sow earlier, but you may need a heated propagator.
Here are some guides on our web page to get you off to a great start:
Q: My chilli seedlings are leggy; what should I do?
A: If you can move your chilli seedlings to a brighter spot, that will help. You can also move the seedlings apart from each other to provide more all-round light. If you still have leggy plants when you decide to pot-on, chilli plants are quite happy to be replanted to a new soil level, so you can bury part of the stem to stabilise the plant then. This should be less of a problem if they start to get better light and are not too crowded. Chilli plants that want to be big (like Padron peppers) will need better light than small plants (like Prairie Fire), so if you only have a small area with good light, use that area for your larger plants
Q: When using your plugs, how should I sow them and pot them on?
A: At the farm, when we sow chilli seeds into plugs, we usually sow two seeds per plug and pick-out the weaker seedlings to leave just one per plug. Once the seedling in the plug has three or four true sets of leaves, we pot-on into a 1ltr (about 6”) pot.
Potting on and Pot Size
Q: What pot sizes should I use for chilli plants?
A: We recommend using a 3” (7.5cm) pot for the first transplant, and then using progressively larger pots as the chilli plant develops. Our experience is that the plants do better with a fairly gradual size increase, rather than potting on into a pot that is much larger than the plant needs, for example: 3”, 6”, 9”, and 12”. The final pot size will depend on the growing conditions, the variety of chilli and where the plant is being grown.
Q: What should I feed my chilli plants and how often?
A: We recommend Chilli Focus, available from our web page in three sizes. A weak solution should be used initially (see bottle for guidelines), building up as the plant matures. A weekly feed is usually sufficient, depending on the richness of the compost, and how often you re-pot.
Q: What type of plant food do chilli plants like?
A: The best approach is to use a reasonably balanced feed, but one that has a good quantity of potash (potassium) to encourage flowering and fruiting. We sell a feed called Chilli Focus which is formulated for chilli plants.
Growing outdoors (e.g. in a pot on a patio)
Q: Can I grow chilli plants in a pot outside on a patio?
A: Yes, you can, as long as there is no risk of frost. Here are a few tips to get the best from outdoor chilli plants:
- Go big on the drainage in the compost/raised bed to prevent the roots being waterlogged.
- Use black pots – they help to keep the compost warm.
- Use rain guards around the plant base to deflect heavy rain.
- Consider bringing the pots indoors during bad weather.
- Use soil-based compost (heavy, so less likely to blow over) John Innes No.2 is a good choice.
- Select small/light fruited varieties (less likely to get damaged in bad weather).
- Pick the fruits green to maximise the crop – expect a lower yield compared to greenhouse growing.
- Support the plant with canes and place in a warm, sheltered spot.
Flowering and Fruiting
Q: Does it help to hand-pollinate chilli flowers?
A: Chillies have ‘perfect flowers’ meaning they don’t need help from another plant or pollinating insects to set fruits. In our crop tunnels, we don’t hand pollinate, but there is some pollination care of bees and hoverflies in the polytunnels. The vast majority of our crop will be from self-pollinated flowers. Chilli plants usually produce an abundance of flowers – more than they need or could sustain if they all turned to fruits. There is some evidence that fruits produced from cross pollination tend to be larger and contain more seeds, so it would be worth trying some hand pollination for the fruits that you want to be bigger. To hand pollinate, use a fine art brush.
Q: I am having problems with fruit yield; how do I improve the cropping?
A: These steps will help to encourage the production of flowers and set of fruits on chilli plants:
- Warm night-time temperature (comfortably over 15c)
- Avoiding periods of extreme heat in the day. Over 40c will cause flowers to abort. 25c is ideal
- Too much nitrogen can cause the plant for forget to flower
- Too little potash can cause set flowers to abort (try our Chilli Focus feed).
- Soil too wet or too and high winds
Q: My chillies fruits have black marks on, is that a problem?
A: As long as the fruits are firm, the black is just an early sign of ripening. There are a few chillies that we get asked about concerning blackening – Jalapeno very often has black streaks before ripening. We sometime get the same question concerning the plants which can develop black marks around the divisions in the stems, which is very common and not a problem.
Q: How do I control Spider Mites on my chilli plants?
A: Spider mites can be a problem during periods of hot, dry weather. These conditions will greatly increase the lifecycle of Spider Mites, allowing them to get to such large numbers that they can harm the plant. The signs are very fine web on the under-side of the leaves, and ‘windows’ that can be seen from the top of the leaves.
Spider Mites can be controlled by regular spray or water on the under-side of the leaves, or by using a non-toxic spray, like the SB Invigorator we sell online:
You can also consider cutting off heavily infested section of the plant to stop the spread.
Q: How do I control aphids on my chilli plants?
A: If you look on the under-side of the leaves, you may spot greenfly (aphids) during the Summer months. The easiest way to clear the plant is to take it outside (or away from its normal growing area); tip the plant so you can see the under-side of the leaves, and gentle brush them off. Smaller ones may need to be squished. If you repeat this for a few days, that should bring it back under control. For extreme cases, we sell a non-toxic spray and feed:
White ‘flies’ on the top of the leave are probably shed skins of aphids, and will wash off with a hand-sprayer.
Q: I would like to keep my chilli plant over winter, what should I do?
A: Chilli plants tend to stop growing and flowering during the winter months in the UK. If the plant is coming in from a greenhouse or patio, you may need to prune it to fit the available space. You can lightly prune to re-shape the plant or heavily prune to just leave the main stem. If the plant grew to an ideal size, then a hard pruning will allow it to re-grow with the same fruit cover and size the following season. Keep the compost just off dry while the plant is dormant and keep it somewhere light, but not with extremes of temperature. In the UK, overwintered plants usually start to become active in March or April, depending on where they are being kept. Fresh compost in the Spring will help to get them going.
Q: How do I dry the chillies I have grown?
A: Drying chillies is more about air circulation than heat, so place them in a well-aired basket and put them somewhere warm – such as over a radiator. Spread the chillies in a thin layer and leave the stalk attached. They should dry out in a few days. Chillies with thick flesh (like Jalapenos) are not a good choice for drying. A thin-fleshed chilli, like Ring-of-Fire, is an easy chilli to dry. Once dry, store in an airtight glass jar or tin, and keep out of direct sunlight to preserve the colour and flavour.
Q: I would like to collect and save chilli seed for next season, do you have any tips?
A: The ideal time to pick a chilli to be used for seed stock is just as it reaches its ripe colour. Cut the fruit open and with a blunt instrument, scrape the seeds out onto paper. Place the seeds in a warm spot out of direct sunlight until the dry a little – this will prevent them developing mould. Store wrapped in foil and placed the foil wrapper in a tin or glass jar and lid. Store the jar/tin in a cool place (in a cupboard). The fridge is good if you want to keep the seed for several years, but they should be fine for a couple of years if they are dried a little before storing.