Chili Peppers

If you like your food spicy, chili peppers are a garden necessity.

Scotch bonnets (Secretlondon) CC BY-SA 3.0

Carolina Reapers (Dale Thurber) CC BY-SA 3.0

Why the heat?

The reason chili peppers are hot is because they contain capsaicin. Capsaicin is found, in varying degrees, in nearly all peppers. Sweet bell peppers contain little to no capsaicin. Powerfully hot peppers are used in Africa to keep elephants out of gardens and other crops. Birds, on the other hand, do not have those particular pain receptors, so they are largely responsible for the spread of wild pepper plant seeds. Before we learn about different varieties of hot pepper and how to grow them, a word on Scoville heat units.

​Scoville heat units

Scoville heat units (SHUs) are used to measure perceived heat or spiciness, as a function of capsaicin levels. The American Spice Trade Association (ASTA) uses high-tech chromatography and some crazy math to measure the relative pungency of a sample. A Scoville heat unit ends up being one part capsaicin per million units of dried pepper. Since it matters just how dry a sample is, people trained to taste hot peppers add their subjective data. [Who knew that was a job?] For comparison, tabasco sauce rates 3750 SHUs and Huy Fong Sriracha rates 2,200 SHUs.

Hot pepper plants are small shrubs with striking red, orange, or yellow fruits, depending on the variety. These plants look great in a landscape and they can provide you with peppers all summer long.

Chili pepper plants

Chili peppers are members of the nightshade family, along with tomatoes, potatoes, and eggplants. These hot peppers originated in Mexico, but are now found around the globe, with China producing half the world’s total crop. Chili peppers were domesticated over 6,000 years ago. There are five basic domestic species of chili peppers (and countless variations):

• Capsicum annuum - bell, banana, cayenne, and jalapeño chiles
• Capsicum frutescens - tabasco and Thai peppers
• Capsicum chinense - naga, habanero, Scotch bonnet
• Capsicum pubescens - rocoto chiles
• Capsicum baccatum - Bishop’s crown peppers

Serrano pepper plant (Cindy) CC BY-SA 2.0

How to grow hot peppers

These plants need a long growing season to reach full flavor. Seeds are usually started 6 to 8 weeks before the weather is warm enough for them to be outside. Peppers need nighttime temperatures that are at least 50 to 55°F, to prevent blossom drop. Start with clean, disinfected pots that are 2 to 3 inches deep and that have drainage holes. You can disinfectant old containers by washing with a household cleaner, such as Lysol, and allowing them to air dry in the sun. This is an easy way to prevent future disease and pest problems. In the same vein, use new potting soil, rather than dirt from your garden. Seedlings are much more delicate than your mature plants, which may be strong enough to withstand existing pests or diseases. Also, use seed designated with a letter “V” - this indicates resistance to verticillium wilt.

Fill containers 3/4 full of moist, nutrient rich, organic potting soil. Seeds should be placed 1 inch apart and covered with 1/4-inch of soil or vermiculite. Wet the surface without disturbing or uncovering the seeds. You can use plastic food trays to hold your pots - the clear plastic covers make it easy to maintain moisture levels and the bases protect your furniture. Plastic wrap held in place with a rubber band can also be used. Once seeds germinate, remove the covers. Be sure to label your pots - popsicle sticks work well and they decompose in the garden later on.

Since chili plants are generally started when it is colder than their seeds like, you may want to invest in a seed heating mat. [Put aside the temptation to use that old heating pad - they get too hot, are not designed to handle moisture, and can be a fire hazard.] Sprouted seeds will need full sun or a grow light. Keep the soil moist, but not soggy.

Thai pepper plant (Daniel Risecher) CC BY-SA 3.0

Caring for seedlings

As the first set of true leaves emerge, thin plants to 2 inches apart or up-pot into larger containers. Water every other day, to avoid hydrophobic soil. Pick up your pots to make sure they feel heavy from the water. Check seedlings regularly for signs of aphids, mites, or snails. These pests can be hand-picked or wiped off with a wet paper towel. Continue to up-pot until outdoor temperatures are warm enough for your chili peppers.

Transplanting hot peppers

Prepare your seedlings to be transplanted by watering them to the point of run-off. Then, place one hand over the soil, with the plant stem between your fingers, and flip the pot upside down. You may need to jiggle or tap the pot to break the soil loose. If roots have really taken hold of the pot, use a sharp, clean knife to cut along the sides of the pot. Seedlings should be planted in a sunny location, 10 to 18 inches apart, depending on the variety. If watered regularly, chili peppers perform especially well in heat islands.

You can improve the plant’s root system by removing any growth from the bottom 1/3 of the stem and burying those nodes below the soil surface, the same way you might for tomatoes. These nodes will produce roots, giving your plant access to more water and nutrients. Water deeply, right away, to help the soil settle, removing air pockets, and keeping the roots moist. And be sure to label your plants! All peppers are self-pollinating, but crops are significantly larger when other pepper plants are nearby. Note: if you plan on saving seeds from your hot peppers, be sure to keep different varieties away from each other, as they will cross-pollinate.

Caring for hot pepper plants

Pepper plants benefit from a thick layer of organic mulch placed around, but not touching, each plant. Use a hose to water your plants thoroughly, at first. This will help the soil settle and keep the plants well hydrated. Once the roots take hold, you can use drip irrigation or a soaker hose. Plants should be side-dressed with nitrogen about once a month for healthy leaf growth. In August, you can increase feedings to once every two weeks. As fruit begins to mature, you can increase their hotness by only watering once a week and allowing the soil to dry out between waterings.

New Mexico peppers drying on the plant (Dicklyon) CC BY-SA 4.0

Harvesting hot peppers

Each pepper has a color that indicates it is ready to be picked. Read your seed packet or check online or at your local library to learn more about your specific varieties. Many peppers are harvested while immature, the flavor actually becomes sweeter as the fruits mature.

Pepper pests and diseases

Pepper weevils, cutworms, aphids, armyworms, flea beetles, leafminers, corn earworm, leafrollers, nematodes, weevils, thrips, spider mites, tomato psyllids, and whiteflies can all become pepper plant pests, though I have rarely had any serious problems. I have found that birds are more likely to become a problem. Most pepper diseases are of the fungal variety: powdery mildew, crown rot, root rot, verticillium wilt, and tomato spotted wilt are common with improper irrigation. Also bacterial spot, several mosaic viruses, blossom end rot, and curly top may occur. Sunburn, or sun scald, can also be a problem on pepper plants with insufficient leaf cover. Personally, I have had excellent results growing pepper plants under my fruit and nut trees.

Make a little space in your spring planting schedule to start some chili pepper plants for yourself and your friends!