Horticulture Magazine
red chillies hanging amongst foliage

Passionately liked nearly the world over, one or another type of chilli is an essential ingredient for the respective cuisines of nations as disparate as Mexico, Thailand, India, and Italy.

Chillies are best known – and rightfully so – as a hot, spicy food. However, the hotness of different chilli varieties covers an incredibly wide range. Furthermore, chillies also have width and depth in flavour.

No, it’s not just fire-breathing types or entrants in chilli-eating contests who are fond of chillies and would like to grow these tasty little things – yes, ‘tasty.’ Of course, chillies are primarily a spice and produce a ‘hot’ sensation but this heat has an exceptionally wide range from tickling and teasing all the way to painful and injurious, but there’s also a taste component.   

So yes, chillies are not only about and all about the heat, they’re also about taste and flavour. Flavour includes different kinds of ‘spicy’ plus sweet-spicy, fruity-tangy, stinging, darkly smoky, sour or tart, and so on. Different chillies also have varying dryness or moistness. Not to forget that different chilli varieties not only have different tastes but often have distinctly different scents and ‘finishes’ or aftertastes.

Back on the point of spiciness, the heat or pungency of a particular variety of chilli is a quantifiable value, as many readers may know. In 1912 – over a hundred years ago – Wilbur Scoville, an American pharmacist, devised a not-too-precise but ingenious method to measure the heat or spiciness of chillies. Very concisely, he had volunteer tasters try out diluted solutions of various chillies. (The inverse of the) the dilution at which a particular chilli’s heat became undetectable was that chilli’s heat rating. This number came to be called ‘Scoville Heat Unit,’ abbreviated as SHU. Chillis (or peppers) that have no heat and are classified as ‘sweet peppers’ have 0 to 100 SHUs. For informative purposes we mention the SHU value for each variety of chilli we list in Varieties, underneath.

multiple types of chilli peppers on a market stall
Chillies, Chillies, and More Chillies. SHUs from 0 to 100,000!

All chillies are species of Genus Capsicum. This genus – alongwith potatoes, tomatoes, and many other plants, some of them quite surprising – is a member of Family Solanaceae, the Nightshade Family of plants.

Capsicum genus has five species: Capsicum annuum, Capsicum chinense, Capsicum frutescens, Capsicum pubescens, and Capsicum baccatum. Each of them contains numerous varieties and a great number of hybrids as well. A sizeable majority of the varieties that are used all over the world belong to Capsicum annuum and Capsicum chinense. The first includes most of the well-known ‘normal-hot’ varieties and the second most of the well-known ‘super-hot’ ones.

The heat or spiciness of a chilli comes from capsaicinoids which are a class of chemical compounds of which capsaicin is the most common. Capsaicinoids are found in all chillies in concentrations from trace or negligible to off-the-scale.

In the kitchen we use chillies as a spice (and bell peppers as a vegetable) and are free to see and treat them as such; however, all Capsicum species, be they whatever kind of chilli, are fruits from a Botanical perspective. 

It is worth noting that the genus name ‘Capsicum’ is often used as a synonym for mild bell peppers which are actually a type of Capsicum annuum. Bell peppers are somewhat challenging to grow, especially for hobbyists. The good news is that chillies are quite easy to grow, and, as a general rule, the smaller the chilli, the easier to grow it is. In this article we focus on ‘Chillies Proper’ – the hot stuff – and not on Bell Peppers.

Chilli plants in their native Tropical and Sub-Tropical Zone habitats are perennials. In temperate and cool regions they are usually grown as annuals and – unfortunately – even treated and viewed as such. We shall propose that they be grown, even in the British Isles, as the perennial shrubs that they are. Likewise, in this overview we do not treat chillies as gustatory Hydrogen Bombs but as a pleasurably piquant, spicy, and even hot-hot food ingredient.

Remember that, as a general rule, the quicker a chilli is picked, the less spicy it is and the less developed its flavour; the more it matures on the vine and the later it is harvested, the more hot it becomes and the greater its nuances and depths of flavour. Different varieties have different ‘ranges of maturity,’ so to speak.


Official Plant NameCapisicum
Common Name(s)Chillies
Plant TypeFruit
Native AreaCentral & South America
Hardiness RatingH1C
ToxicityEdible Fruits
FlowersFlowers followed by edible peppers
When To Sow (Indoors)February, March, April
Plant OutJune
Harvesting MonthsJuly, August, September, October

Full Sun





Bloom Time


Most Soil Types

Moist but well drained


Background and Origins

Capsicum anuum species were and are indigenous to Central America, and Capsicum chinense species to the landmass we know as Venezuela, Guyana, French Guiana, and Suriname. Their fruits, chillies, were known and consumed in South and Central America since at least 8000 B.C. The plants were domesticated in about 6000 B.C. in what we now know as Mexico, the very southern part of it. 

illustrated mexican icons including piñata, cacti, sombrero, tacos, aztec temples and margaritas
The Chilli is an Essential Component of Mexican Symbols and Symbology

Several thousand years later in the 1490s when Christopher Columbus and then the Spanish conquistadors made landfall in Central and South America, they observed that chillies were a staple part of the Aztec and Mayan diet. It was, in fact, Columbus who was responsible for introducing this New World fruit to Spain and Portugal near the end of the Fifteenth Century. Within a couple of decades this spicy delicacy had established a foothold in Turkey and Italy. 

As such, believe it or not, until about 1500 only Central and South Americans had enjoyed this delicious spice!

Though we may associate chillies with Thailand, India, China, and Vietnam, those nations are latecomers to the Chilli Party. Different species and varieties found their ways to these lands during the 1500s via the Silk Route and other trade routes, and these nations evidently adopted the fruit as their own, as seen from their respective cuisines. In fact, India and China soon became among the world’s largest cultivators and exporters (of some or another species and varieties) of chillies, which they remain to this day.


For the purposes of this article, chillies are not props for showing off in chilli-eating competitions but are a food ingredient. Therefore, we do not discuss the Nuclear Bomb Chillies – let alone Dragon’s Breath or Carolina Reaper. Nor do we list exotica like black chillies.  

A very nice assortment of sensible choices selected for usability in the kitchen, enjoyability in dishes, and tingle-tastiness on the palate, is presented underneath. We list these in order of increasing heat and spiciness since that is, after all, the primary attribute of chillies.

Anaheim or California – As this variety’s name suggests, it is very popular on America’s West Coast among the Caucasian-American population (but not so much the Hispanic-Americans). This dark green-to-red variety is the ‘go-to’ chilli for homemade dishes, being very mild and piquantly flavourful. Perfect for kids and geriatrics who clamour for spicy foods! Only 500 to 2,500 SHUs.

an anaheim green chilli up close
The Anaheim or California Chilli

Ohnivec – This little-known chilli is a fairly ‘adjustable’ variety; more so than most. Pick it young and yellow and it is totally mild; pick it when it’s deep red, and it has a bit of a kick (but only a bit). At 20 to 25 centimetres these babies are BIG. Moreover, these plants bear profuse fruit. It is an easy-to-grow variety, is also easy on the palate, and has a ‘juicy’ taste. 1,000 to 2,500 SHUs but specimens may reach 3,500 SHUs.

Hungarian Wax or Hungarian Hot Wax – This mild variety is very easy to grow indoors. It is not only well suited to the British climate, it is also well suited to the British palate! This popular variety starts off yellowish-green and turns red on the plant. It is one of those whose heat is very strongly dependent on its maturity on the vine. 5,000 to 10,000 SHUs but specimens may range from a low of 1,000 to a high of 15,000. R.H.S.’s Award of Garden Merit.

Jalapeno – Though somehow this name usually conjures up images of intense heat, a Jalapeno is actually one of the milder varieties, ranking exactly nowhere on the H-Bomb scale. This biggish and thickish green chilli is one of those flavourful ones, having – besides a pleasant dose of heat – citrusy-tangy taste. Down in Texas, a pizza is not considered complete without Jalapenos. 2,500 to 8,000 SHUs.

pizza laid on a wooden table with meat and jalapenos
Making Pizza Without Jalapeños is Illegal in Texas!

Serrano – One might call this variety a smaller and hotter version of a Jalapeno. Though this chilli starts off green and progresses to orange or red (or yellow), it is usually picked green. Unlike a Jalapeno, the Serrano is not often used as a topping or diced in foodstuffs but is roasted or used to make salsas and sauces. 10,000 to 22,500 SHUs.

Calabrian Chilli or Peperone Picante Calabrese – If a chilli can be called ‘flavourful,’ this one is at least a prime contender. A deep, lovely red in colour and with that classic chilli shape, the Calabrian has a nice level of heat but has a wonderfully complex flavour, being tangy, fruity, and a little smoky. This versatile chilli is as suitable for home-cooked foods as it is for high-end cuisine. 25,000 to 40,000 SHUs.

Bolivian Rainbow – Though far from an ‘essential’ variety, you just have to mention this pretty baby – after all, it’s a two-in-one, being a highly ornamental plant but also a bona fide chilli. At any given time during the fruiting season, this plant bears its small, inverted fruit in yellows, oranges, reds, and purples – this plant is Nature’s Pixie Lights! At the same time they are that ‘just right’ hot and spicy, and are even easy to grow. 20,000 to 40,000 SHUs.

multi coloured chillies on a Capsicum Annuum plant
Are These Chillies or are These Pixie Lights?

Cayenne – If it’s long, thin, and red, it’s a Cayenne Chilli. Cayenne powder and flakes, so commonly found in Tex-Mex style restaurants, is the dried form of the Cayenne Chilli. Also, many or most Spanish or Mexican style hot sauces have Cayenne as an ingredient. Tried diced or sliced, you will find an appreciable level of heat. It has a very zesty and pungent, slightly smoky, taste. 30,000 to 50,000 SHUs.

Bird’s Eye or Thai Chilli – Identified with Thailand to the extent that it is even called ‘Thai Chilli,’ this narrow, pointed chilli packs near-bomb-level heat. Unlike most other chillies, this one is borne upright (pointing upwards). Used in most Far-Eastern cuisines, this is the chilli that gives Thai Cuisine its distinctive hot spiciness, a tingling, citrusy, and very tasty heat. It is too hot to eat comfortably except finely chopped, and is wonderful to make sauces, curries, and pastes with. 50,000 to 100,000 SHUs.

Habanero – This is an extremely hot naturally-occuring chilli and this is where the chilli heat-bombs begin. Not merely super-hot, the Habanero is tasty and citrusy. Unlike our other varieties this one’s a type of Capsicum chinense. Though it did not originate in Mexico, it is now claimed by the Mexicans as their own and is a widely-used spice in Mexican cuisine, sauces, and pastes. Habanero Chillies are easy to grow and the plants are productive but the fruit can hardly be chopped up, ground, or blended and added to homemade food – after all, you don’t want to provoke a domestic civil war! SHU 100,000 to 350,000 SHUs but some cultivars go up to 600,000 SHUs.  R.H.S.’s Award of Garden Merit.

Red and green Habanero peppers on white background
What is Mexico’s Pride and Joy – Hugo Sanchez or the Habanero Chilli?

Habitat and Growing Conditions

Chillies grow best in a loam mix with a fair amount of organic compost and manure but little clay. Soil pH should hover right around Slightly Acidic.

They are not winter-hardy at all, being indigenous to Tropical and Sub-Tropical climates. They prefer full sun locations.

In the British Isles you need to start off chillies in seed pod trays or small pots indoors or in a greenhouse. (Chillies may be kept indoors or in a greenhouse year-round provided they get a lot of sun.) Many chilli varieties can be grown even in growbags. 

After the plants have developed you would transplant them to suitable containers or in a bed outdoors. If you grow chilli plants outdoors then they will effectively be annuals but if you grow them in containers, then you can overwinter the plants indoors in a sunny spot or in a heated greenhouse and they will flower and fruit for about three more years.

How to Grow Chillies

Sow seeds in preferably February otherwise in March. 

You may transplant your growing chillies more than once if you wish. The rule is to pot on when roots become visible through the drainage hole or when it appears that the root system has filled up the pot.

Chilli seeds do not germinate as readily as do most vegetables and fruits. To up the chances of germination, dampen a few paper towel sheets, put seeds in them, rumple the towels, and let them be for a day or two before sowing them.

Prepare small – 6.5-centimetre – terracotta pots with a mix of seeding compost and organic soil without clay or peat.

Bring out your seeds wrapped in paper towels. Some or many may be starting to germinate.

Place two or three seeds just a touch under the surface of the soil.  

Spread a bit of perlite or vermiculite on the surface for absorption and retention of moisture. If you use vermiculite be aware of its health risks and be sure that it is not disturbed. Water well.

The pots can be kept in a heated greenhouse or in a sunny spot indoors at a temperature hovering around 20° Centigrade. 

young chilli plants in plastic pots
Chilli Plants are Quite Easy to Grow in Pots

Water them every two days so that the soil stays moist though it should not stay wet. Feed them, sparingly, with a liquid fertilizer like Chili Focus. Alternatively, feed them, sparingly, with 5-5-5 fertilizer to start off with.

Keep an eye on the plant’s height and overall shape as it grows. When you feel the plant has reached a desirable height and needs to have more spread, pinch out the tip. The plant will then start becoming bushier.

You will need to transplant the young plants at least once. Do so when a plant’s roots start peeking through the drainage holes, when the root system has just about filled the pot, or in early-to-mid May.

Prepare 18- or 20-centimetre pots with a good organic loam including compost but very little clay and no peat. Transplant one or more developing plants, each to its own pot. 

If you decide to transplant the plants in an outdoor bed, do so when the soil temperature is not below 20° Centigrade.

Stake the developing plants as and when necessary.

In mid-to-end May you can move your chilli plant pots outdoors.

From June, water the plants a little more and continue to feed them with Chili Focus or with a 5-5-10 (and not 5-5-5) fertilizer.

Be aware that chillies not only exude and give out warmth and heat, chilli plants also take in and need warmth and heat. They dislike cold.

Feed a little more regularly and generously after the plants have flowered and have started to bear fruit.

Harvesting Chillies

As the season progresses, be aware that the ambient temperature should not rise too far above 30° Centigrade as that causes many chilli plants to drop blossoms.

You can harvest chillies on an as-needed basis, with a couple of provisos. First, though, do not pick or pluck chillies; cut the stalk with secateurs or a sharp knife.

You may harvest chillies as needed at any stage of maturity; so, for Hungarian Wax, you could pick fruit when it is yellowish-green, deep green, orange, or deep red. 

Here’s what you need to keep in mind and balance according to your needs:– The earlier you pick chillies, the milder the heat and the less developed and one-dimensional the flavour, but the greater the impetus to the plant to produce fresh flowers. The later you pick them, the higher the heat and more well-developed, intense, and fuller the flavour but the plant will not flower and fruit as profusely. It’s a classic choice between quantity and quality.

3 hungarian wax chillies held in hands at different stages of ripeness
Hungarian Wax Chillies at Three Levels of Ripeness

If you have kept your plants outdoors, to extend their lives bring them back indoors or put them in a heated greenhouse in mid-late October.

Discontinue feeding the plants until January or February. 

By December you may notice that the plants have become bushy and unkempt. Trim them so as to tidy them up but do not prune aggressively.

In the January-February timeframe start feeding the plants again, sparingly, with Chili Focus or 5-5-5.

Common Diseases and Problems

In the British Isles you need to watch out for aphids and whitefly, and also red spider mite. Growing chillies in greenhouses increases the chances of the plants being attacked by these pests.

Besides the usual biological controls and cures, one way to avoid these problems is to harvest fruit by cleanly cutting the stalk with a sharp secateurs. 

Where to Get Chillis

Chilli seeds are best bought from speciality seed merchants, preferably speciality chilli seed sellers. Yes, there is such a thing as a speciality chilli seed seller! Chillis have a devoted and increasing fan club and specialists stock seeds that are not only of high quality but also available in a wide variety. In addition, chilli hobbyists collect and sell or trade seeds.

You can find quite a number of such sources online. All the varieties listed above, and then some, will be available.

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