Introduction: 16 Tips on Growing Hot Chilli Peppers in a Cold Climate

If anybody reading this has actually tasted my cooking, you will know how important chillies are to my daily routine. Most of the meals I have cooked without chillies are fairly disgusting, with the possible exception of cheese on toast, although this too is normally served with a generous quantity of chilli powder. It is therefore essential to me personally to have a reliable source of chillies, especially after the impending apocalypse and the only way to ensure the uninterrupted continuity of supply is to learn how to grow them myself.

It's now the beginning of April and the chilli planting season has started. Now is the time to act, so I bought myself some seeds and equipment and wrote myself a comprehensive set of instructions.

The main key to growing hot chillies in cold climates is apparently temperature and humidity. Chillies hate the cold! And I must always remember Twmffat's 1st law of chilli growing: 'The hotter the chilli, the more temperature dependant it is and the longer it will take for the seeds to germinate and the plant to grow to harvest time'.

I also want to say thanks to everybody who has contributed to this project in the comments section below. It has been a real collaborative effort!

So, after some very extensive scientific research, here are my complete results:

  • Use Twmffat's 1st law of chilli growing to decide which variety of plant you want to grow. Have a look at step 3 for possible varieties and their 'heat' value.
  • The seeds can be sown in a good quality compost in multi cell trays and germinated in a warm place. Sometimes, especially with the hotter varieties, germination can take up to 4 weeks and so investing in a temperature controlled propagator unit might be a good idea. The ideal temperature is between 27 and 32 degrees C and it is important that this temperature does not fluctuate too much. The total possible temperature range is from 21 to 38 degrees C although germination may be more erratic.
  • The plants need good drainage and hate to be stood in water, so make sure your compost is of the free draining type, if possible. Sand can be mixed in if the compost is too hydrophilic.
  • Propagators - These vary in sophistication from the basic 8 watt system to the fully controlled 50 w delux versions. I myself chose a 20 w unit with no temperature control as it was cheap. I used a programmable timer to regulate the temperature and covered it with some insulation to keep the heat in. The instructions with the unit do say not to do this, but I don't see why not? The timer was programmed to come on for 40 minutes and then go off for 20 minutes as this kept the soil at a constant 28 degrees C quite nicely. Other options include using a digital water bed heater or a heated floor in your bathroom or an airing cupboard.
  • Use a digital thermometer to check the temperature stays within the correct range. Put the probe into the soil close to one of the actual seeds to get the best reading.
  • Seeds can be planted in January through to the end of March and the fruit will take between 80 and 180 days to ripen, depending on the seed variety. Soak the seeds over night in diluted feed solution or for 2 hours in potassium nitrate solution (0.33g per litre) to reduce germination times by up to 50%, and then plant the seeds 5 mm deep. For saved seed, see below.
  • Water thoroughly with warm water whenever the top of the compost is beginning to look dry, being very careful not to over water. Cold water may 'shock' the seedlings and delay growth. Use a pressurised spray bottle to water the chilli plants as this is much more gentle than your garden hosepipe. And apply Twmffat's 2nd law of chillie growing: 'Be generous and infrequent rather than frequent and ungenerous'.
  • Check the seed trays every few days or so for dryness and signs of germination. Once the seedlings have emerged they will need to have light so move them onto a window sill or somewhere warm and light. A glasshouse may be too cold at night time to begin with, so in the house may be better.
  • As the plants grow, they will need potting on so as not to overcrowd the roots. They can also be fed with liquid food suitable for tomatoes, especially if the leaves start to look a bit pale in colour. The maximum temperature should be 36 degrees C and the plants do enjoy high humidity. The minimum temperature is 16 degrees C so think carefully where the plants should be kept, especially with regards to night time temperatures. In cold climates it's generally going to be a glasshouse, poly tunnel or conservatory and it may even need to be heated/insulated during the night time.
  • The plants can be planted through aluminium foil so that light is reflected back off the top of the soil back onto the underside of the leaves. This can also reduce pests as they can no longer hide from the sunlight underneath leaves any more.
  • For the fruit to form, the flowers will need to be pollinated either naturally by insects or by hand using an artist's paint brush and the flowers may fall off prematurely if the plants get too cold. Use the paint brush between noon and 3 pm for best results.
  • The flowers will eventually fall off naturally and the fruit will then grow and can be harvested when they are filled out and become firm crisp and glossy. Pick one fruit to begin with and test it for heat and flavour. Remember, some of the varieties are EXTREMELY HOT! If you do want to maximise the heat of your chillies, stop watering the plants so much when the fruit has formed and if you want to maximise the flavour, keep on watering as normal.
  • Chillies are ready for harvesting when the pods come away nice and easily from the stalks. Also, upon inspection inside the pods, the seeds should be well developed ie the same size as they were when the originals were planted.
  • The harvested fruit can be stored very effectively in the freezer and most of the plants themselves can be treated as perennials, with some pruning needed in the Winter season. Dig the plants up, put them in pots and move them to somewhere warm and sunny and free from frost. Next season they will grow back stronger with an earlier and more abundant harvest.
  • If you are growing one single variety of chilli, then save some of the seeds from your chillies for growing next year's plants. F1 hybrids can not be saved, but normal open pollinated varieties work well. Gently dry the seeds just enough to stop them going mouldy and put them in a paper bag or envelope and store them in a dark cool place away from mice. If you do have more than one variety in the same location you will get cross pollination, which will produce a new plant with unknown properties. When you come to use the seeds, wash them for 30 seconds in diluted detergent to remove the waxy natural germination inhibitor, then rinse and soak in water for 2 hours before planting. Some commercially bought seed may also need washing.
  • Chilli plants may not always flower in the first year, especially the hotter varieties, but can be over wintered in a frost free conservatory or glasshouse to get a head start in the next season. The plants should be pruned back hard and watered every now and again dependant on ambient temperatures
  • If you live where there is a lot of wind (see"Wyoming" in the dictionary"!!!) staking plants is a must but also helps those plants that have large fruit and/or are heavy producers.

Step 1: Equipment

Disclosure: I have a 'material link' to so you buying the products above will earn me cash.

Step 2: Seeds in Order of Heat

Twmffat's 1st law of chilli growing: 'The hotter the chilli, the more temperature dependant it is and the longer it will take for the seeds to germinate and the plant to grow to harvest time'.The 'heat' of the fruit is measured in SHU or 'Scoville Heat Units'.

Carolina Reaper (Very hard to grow)

1,600,000 SHU

180 days to grow

Bhut Jolokia (Hard to grow)

1,000,000 SHU

160 days to grow

Hot Chocolate Habanero

600,000 SHU

140 days to grow

Orange Habanero

350,000 SHU

100 days to grow

Paper Lantern Habanero

350,000 SHU

90 days to grow

Red Scotch Bonnet Capsicum C.

200,000 SHU

90 days to grow

Long Slim Cayenne

80,000 SHU

80 days to grow

Ring of Fire (Easy to grow)

80,000 SHU

80 days to grow

Step 3: Summary of Temperatures

  • Ideal range for germination: 27 - 32 degrees C or 80 - 90 degrees F
  • Complete range for germination: 21 - 38 degrees C or 70 - 100 degrees F
  • Minimum growing temperature: 16 degrees C or 61 degrees F
  • Maximum growing temperature: 36 degrees C or 97 degrees F
  • Step 4: Final

    Please enjoy your hot chilli plants and if you do grow the hottest varieties, be careful, as they are incredibly strong.

    If you've got any good tips that I've missed out, please leave them in the comments section and I'll transport them over to the relevant section. Thank you.

    More Chilli related Instructables can be found here:

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