Choosing and Growing Hot Chili Peppers

Closeup of chili peppers growing

The Spruce / Gyscha Rendy

Chili peppers and hot sauces are commonplace everywhere from snack foods to diner booths. The competition to produce the hottest pepper results in new varieties coming to the market every few years. Whether your tastes run to just a little heat or a pepper that makes your eyes water, there are dozens of varieties to choose from, which helps make chili peppers popular around the world.

Types of Chili Peppers

You can't always tell a hot pepper by its name. All peppers are in the genus Capsicum, but here are five species of Capsicum in cultivation. Most of the commonly grown varieties, like cayenne, jalapenos, and serranos, are Capsicum annuum. Many of the Asian hot peppers, as well as tabasco peppers, are C. Frutescens. Habaneros and Scotch Bonnet are C. chinense.  The fiery 'Aji' peppers, like ' Aji Amarillo', 'Aji Colorado', 'Aji Cristal', belong to C. baccatum. And the wild peppers chiltepíns and chilipiquíns, from the regions around Mexico, are C. glabriusculum. However they are classified, there's a lot of variety.

Closeup of cayenne peppers
Cayenne peppers

The Spruce / Gyscha Rendy

Closeup of ghost peppers
Ghost peppers

The Spruce / Gyscha Rendy

Closeup of serrano peppers
Serrano peppers

The Spruce / Gyscha Rendy

chili peppers growing
The Spruce / Grace Thomas  

How Hot is Hot?

It wasn't until 1912 that a pharmacologist named Wilbur L. Scoville came up with a rather ingenious, if imprecise, method for measuring the relative hotness of chili peppers. He diluted the oils from various peppers in sweetened water and had volunteers taste it. Scoville measured how diluted a pepper's oil had to be before the testers could not detect any heat.

The sweet bell pepper came in at zero Scoville heat units (SHU) and set the starting bar. Jalapenos rated 2,500 SHU, which means 2,500 parts of sugar water to 1 part Jalapeno extract. The higher the SHU, the hotter the pepper. Habenero's scored 350,000 SHU.

Today researchers use a chromatography machine, which is much more accurate than Scoville's method. However, the same type of chili peppers grown under different conditions can vary widely in heat level. In fact two hot peppers harvested from a single plant may have different degrees of heat.

Most varieties will change from green to either red, yellow or orange when fully mature. Anaheims, are often harvested while still in their green stage, however allowing jalapenos and serranos to turn red before harvesting often sweetens the flavor along with the heat. Smoke red jalapenos are the pepper used to make the popular chipotle pepper.

While some chili peppers are merely hot, most also have distinct flavors, from fruity to smoky. Habaneros come in fairly high in SHUs and have a distinct citrusy flavor. The poblano pepper, which is mild like the anaheim, has a dark hint of smoke and is the pepper used in the dish chile rellenos. In addition to a variety's taste appeal, the heat (and resulting pain) is thought to stimulate the production of endorphins, which produce a sense of well-being, once the pain wears off. 

Common Types of Chili Peppers to Grow

Besides the botanical classifications mentioned above, chili peppers are often grouped by their SHUs and by the shape of their fruits. Here are some of the most popular varieties, in order of heat ratings:

  • Anaheim: Long, tapered fruits with moderately thin walls. Medium to mild heat (1,000 - 5,000 SHU)
  • Jalapeno: Short, stubby peppers with a slight taper and thick walls. Medium to mild heat (2,000 - 5,000 SHU)
  • Serrano: Short and slim with medium thick walls. Medium to high heat (10,000 - 25,000 SHU)
  • Cayenne: Long, thin, curving fruits with thin walls (perfect for drying). Medium to high heat (25,000- 50,000 SHU)
  • Tabasco: Very short and pointy, with thin walls. Medium-high heat. (30,000 - 60,000 SHU)
  • Thai: Small and slender, with walls. More heat than flavor. Medium-high heat. (50,000 to 100,000 SHU)
  • Habanero: Short, squared fruits with thin walls. High heat. (150,000 - 350,000 SHU)
  • Ghost: Short, squat, slightly tapered fruits with thin walls. Extremely high heat. (1,000,000+ SHU) 
chili pepper harvest
The Spruce / Grace Thomas 

Tips for Growing Truly "Hot" Peppers

While your choice of variety will certainly play a big part in how hot the chili peppers that you grow ​turn out to be, there are a few growing conditions that will improve their heat.

  1. Choose varieties with shorter growing seasons. Some hot peppers don't start setting flowers and fruits until days begin to shorten, in the fall. Peppers with shorter growing seasons will have time to fully mature and develop their heat.​
  2. Hot sun and warm air and soil temperatures seem to increase the heat level in peppers. While you can't control the weather, you can cover the soil with black plastic, to trap and increase the soil temperature.​
  3. Grow your plants on the dry side. Don't withhold water totally, but be stingy with it. Allow the plants to remain dry for several days before watering again.​
  4. Go easy on the fertilizer, especially nitrogen fertilizer, but even compost. Along with minimal water, grow your plants on the lean side. Don't stress your pepper plants but don't pamper them. Get them established in the spring, then let them fend for themselves.​
  5. Don't be afraid to crowd your pepper plants. They will fight all the harder to set fruits.
pepper blossoming
The Spruce / Grace Thomas 


Growing chili peppers with different levels of heat gives you lots of options for using your peppers. It is perfectly okay to use several varieties in your salsa which is one of the most popular uses for chili peppers. They can be stuffed, grilled, baked and sauteed, and added to soups, stews and marinades. Most varieties dry well and can be ground and used as a condiment to punch up just about any dish that you prepare in your kitchen.

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  1. Scoville Scale. “Chili Pepper Scoville Scale | SCOVILLESCALE.ORG.” Accessed August 11, 2021.

  2. Scoville Scale. “Chili Pepper Scoville Scale | SCOVILLESCALE.ORG.” Accessed August 11, 2021.