Peppers! Peter Piper’s Piquant Patience Payoff
A Potted History of Peppers
Peppers – plants of the genus Capsicum, and their fruit – are native to South and Central America and Mexico. Native Americans were eating wild peppers by 7,000 years B.C.E. and had domesticated them by 5,000 B.C.E. The Spanish were the first Europeans to encounter peppers, but the Portuguese were mainly responsible for introducing them to the Old World, via their colonies in Africa, India, and East Asia. The Ottoman Empire brought peppers from India to the Balkans, and peppers then spread into central and northern Europe.
Europeans quickly adopted “pepper” (and its non-English equivalents like “pimienton” and “paprika”) to refer to these plants. Other names derive from Native American languages. “Ají” comes from the Arawak language in the Caribbean. This name is still used in the Caribbean and in South America, particularly to refer to hot peppers. “Chili” and its variants are from Nahuatl, an Aztec language still spoken in Mexico. In some English-speaking countries “chilli” means a hot pepper, whereas non-spicy peppers are called “Capsicums.” “Chile” is used in Mexico – old and New – to refer both to peppers and the country.
The origin of the scientific name Capsicum is unknown. It may derive from the Latin capsula, meaning chest or box, for the way the fruit encapsulates its seeds. Others believe the name comes from the Greek kapto, “to bite”, referring to the fruit’s piquancy. There are about 20 wild pepper species, and five domesticated species: C. annuum, C. chinense, C. frutescens, C. baccatum, and C. pubescens. The numberless types of domesticated peppers are, botanically speaking, cultivars (or cultivated varieties) of these five species.
C. annuum is far and away the species most encountered in the United States, both in the garden and in the food market: Bell peppers, Jalapeños, and about 3,400 others available from the U.S. National Plant Germplasm System are all cultivars of C. annuum.
C. chinense includes Habañeros, as well as the Scotch Bonnet, Bhut jolokia/Ghost pepper, and Carolina Reaper. All of these are famous (or infamous) for their heat, but mild C. chinense cultivars also are common, for example the Ají dulce, an essential ingredient in Caribbean and Venezuelan cooking.
The Tabasco pepper is probably the best-known example of C. frutescens. Another is the Piri piri, or Bird’s Eye. C. frutescens peppers tend to be hot, small, and intensely colored, even when immature, and most ornamental pepper plants belong to this species.
C. baccatum is primarily grown in Bolivia and on the western side of the Andes. Ají amarillo is the most well-known cultivar; it is often ground into a paste that is the backbone of many South American cuisines.
C. pubescens is also popular to the west of the Andes. Its purple flowers and black seeds set it apart from other Capsicum species, which have white flowers and cream-colored seeds. The plants also are a little more cold-tolerant than the other Capsicums. These peppers are often called rocoto or locoto, from the Quecha and Aymara languages, respectively, and red varieties are sometimes called manzano, Spanish for “apple.” The similarity to apples is 100% cosmetic, though: rocotos can be as hot as Habañeros.
Capsaicin is the chemical responsible for peppers’ heat. (Technically, it’s one of six similar compounds in peppers, but it is the most prevalent by far.) It’s not just poetic license to call the sensation generated by capsaicin “heat”: capsaicin stimulates sensory neurons that also respond to high temperatures. Mammals sense capsaicin but birds do not. It’s hypothesized that this is an evolutionary strategy to ensure seed dispersal by birds, which do not have teeth that can destroy pepper seeds.
Capsaicin is not very soluble in water, but it is quite soluble in oils and fats. Cooks can take advantage of this to ensure maximum capsaicin delivery. If less heat is desired, though, using fewer or milder peppers is probably more satisfying than using less butter or oil. Wash hands, knives, cutting boards, etc. that have come into contact with hot peppers, using soap and hot water to remove any traces of capsaicin.
The glands that make capsaicin are in central pith of the pepper, especially in the placenta where the seeds are attached (see photo). Sadly for gardeners whose plants are targets of deer and other mammals, there is no capsaicin in leaves. Seeds also do not contain much capsaicin, though they are often said to. When using peppers in a recipe, cooks can dial up or down the heat level by incorporating more or less of the pith.
Peppers’ heat level is measured using the Scoville scale, which was developed in the early 20th century by Wilbur Scoville, an American pharmacist. The basic method is to extract capsaicin from peppers using alcohol, then dilute in sugar water until heat can no longer be detected by a taster. The level of dilution is then the number of Scoville units. Peppers range from 0 units (Bell) to about 2 million (Carolina Reaper, according to Guinness World Records in 2017). Pure capsaicin comes in at 15-16 million Scoville units. The following table lists several common pepper varieties and their Scoville levels.
|name (species*)||Scoville units||days†||notes|
|Ají dulce (c)||0-500||100||fruity flavor of Habañero but no heat|
|Anaheim (a)||500-2,500||80||hotter when red|
|Banana (a)||0||70||good alternative to Bell for home gardeners|
|Bhut jolokia (hybrid of c, f!)||1,000,000||100||name can be translated as “ghost pepper”|
|Cascabel (a)||1,500-2,500||80||usually dried; seeds rattle|
|Cherry (a)||0-500||75||often pickled; also known as Pimientos|
|Chipotle (a)||2,500-8,000||80||smoked red Jalapeño; often canned in adobo|
|Fresno (a)||2,500-10,000||75||similar to Jalapeño but hotter and sweeter|
|Habañero (c)||100,000-350,000||95||has it all: fruity flavor, searing heat|
|Hungarian Wax (a)||1,000-15,000||60||usually picked before ripe; yellow-green|
|Mirasol (a)||2,000-5,000||70||point upwards on plants, thus the name|
|Pepperoncini (a)||100-500||80||usually picked green and pickled; a bit sweet|
|Poblano (a)||1,000-1,500||75||fresh Ancho; frequent in Mexican cooking|
|Serrano (a)||10,000-20,000||75||similar to Jalapeños but smaller and hotter|
|Tabasco (f)||30,000-50,000||75||brilliant color, lots of heat; used in the sauce|
If you’re just getting started growing your own peppers, you’ll want to choose from the cultivars recommended by experts, and many of them are noted above. Here’s a list to get you started:
Recommended Cultivars (Clemson Coop.Ext./Pepper)
Bell Peppers: Capistrano, Jupiter, Plato, Antebellum, Valencia, Vanguard
Banana Peppers: Sweet Banana, Cubanelle, Banana Supreme, Biscayne, Key Largo
Jalapeño: Jalapeño M, Tula, Mitla, Fooled You
Habañero: Habañero, Tiger Paw NR
Cayenne: Carolina Cayenne, Charleston Hot, Long Slim Cayenne, Super Cayenne II
Other Hot Peppers: Carolina Reaper, Ghost Pepper, Scotch Bonnet, Poblano/Ancho, Serrano
Many highly-recommended cultivars are disease resistant, so you’ll likely want to look for this feature. See https://extension.umn.edu/news/disease-resistant-bell-peppers-good-choice-home-gardens.
Seed starting: Peppers are easy to start from seed. Begin by finding a good source: most seed companies, both local and national, offer a huge variety of pepper seeds. Seed exchanges (e.g. Seedsavers.org) are also a great option. The enormous number of pepper varieties might be daunting at first, so it’s probably best to start with just a couple of varieties, maybe one hot and one sweet. The above table, which lists some common varieties, might be helpful.
Pepper seeds germinate slowly, so get started 6-8 weeks before the last frost. Average frost-free dates in Virginia can be looked up here. (For locations outside Virginia, use the NOAA Climate Data Online Search. Download the data for a weather station and find the spring and fall dates with a 50% chance of reaching 32℉.)
Start the seeds in potting mix or in a mix specifically designed for seed-starting. Put the dry mix in a container – e.g. a flat with wells (wash it thoroughly if re-using) or an egg or yogurt carton (poke a couple of holes in the bottom) – and moisten completely, until a little water comes out the bottom. Put 2-5 seeds, depending on the size of the wells, on top of the mix. Cover with about ¼” of dry mix. Gently moisten the added mix with a spray bottle.
Pepper seeds germinate best between 75℉ (24℃) and 85℉ (29℃), so a heated mat is a good investment. It’s also a good idea to put the potted seeds in a secondary container, whether a tray designed to hold flats or a shallow tub with a flat bottom, to hold any water that comes out of the container holding the seeds.
Put a cover over the secondary container to keep the environment moist. The cover can be a piece of glass or plastic wrap, or a plastic dome made for seed-starting, but either way, be sure there’s enough room for the seedling to emerge. Ideally, watering won’t be necessary before the seeds germinate. If water must be added, only use enough to keep the seed-starting mix moist, not soggy. Otherwise, the seeds may rot. If possible, add water directly to the secondary container and it will wick up into the seed-starting mix.
Seedling care: Uncover the seedlings once most of the seeds have germinated. This will reduce humidity and prevent fungal diseases. “Damping-off”, when the stem wilts and dies at the soil line, is the main danger for new seedlings. It’s more or less impossible to stop damping-off once it’s begun, so prevention is key. If possible, aim a fan at the seedlings. This has two benefits: it will keep the seedlings dry, and the force of the air against the seedlings will stimulate them to grow stronger.
Continue to water the seedlings as before, just enough that the planting mix is moist but not sodden. This will also help prevent disease.
Natural sunlight won’t be strong or plentiful enough for robust growth, particularly in the winter. Fluorescent tubes and bulbs are very effective as artificial lighting, but it’s important to choose the right ones. Seedlings respond best to blue light. In practice this means the “color temperature” of the light source should be 5000 K or 6500 K, and 4100 K at the very minimum. (Another way to put this: “cool white” bulbs/tubes are OK, but “daylight” and “full spectrum” are much better.) LED’s are fine, but the added expense might not be worth the longer lifetime. Along the same lines, any improved outcomes from “grow lights” probably don’t justify the extra cost.
The light source should be as close as possible to the seedlings, but not so close that the seedlings overheat. Ideally, the light source should be directly above the seedlings. The fixture could be suspended from the ceiling or a wire shelf positioned over the seedlings. Stands built from PVC tubes are another good option. Raise the light source as the seedlings grow. Illuminate the seedlings for 12-16 hours a day.
Needless to say, buying pepper seedlings from a garden center or farmers market is absolutely OK!
Transplanting: Transplant seedlings fairly early on into individual 3” pots filled with potting mix. The exact timing will depend on how densely the seeds were sown. If the seedlings are closely spaced, transplant once the first set of true leaves develop, i.e. after the cotyledons that appear with the new seedlings. If less dense, it’s fine to wait until the 2nd or 3rd set of leaves appear. But do not delay much longer than this, or the seedlings will become “leggy”, i.e. tall, thin, and weak. Peppers grow best when their roots are not too crowded. If necessary, transplant the seedlings again into larger pots.
When the last predicted frost-free day arrives, the next step is to…wait. Peppers grow best in warm soil. Nothing is gained by planting them before the soil temperature has reached about 65℉ (18℃). In the meantime, “harden off” the seedlings by putting them outside for a few hours a day at first, gradually increasing the time over the course of a couple of weeks. Be judicious about weather conditions, i.e. don’t set out the seedlings during a cold snap.
Peppers need a lot of sun – 8-10 hours per day is best, 6 hours at bare minimum – so choosing the right spot for the plants is critical. Don’t plant peppers where trees or taller plants will shade them. Orient rows north-south so that plants won’t be in the shadows of neighboring rows.
Remove weeds from the area to be planted. Loosen the soil with a spade, pitchfork, or broadfork. If the soil is dense clay or loose sand, incorporate 4” of compost into the top 12” of soil at this time. This is a lot of compost, ⅓ cubic foot per square foot of area, but the improved drainage and aeration will be worth it. Work fertilizer into the top couple of inches of soil with a garden rake. Ideally, have the soil tested to determine how much to add. (It’s perfectly fine to use a general-purpose fertilizer like 10-10-10, though. Apply about 3 oz. per 100 sq. ft.) A soil test will also measure the soil pH, i.e. acidity. The report will contain instructions for raising the pH with lime or lowering it using sulfur. Peppers grow best at a pH between 5.5 and 6.5. (See Ralph Morini’s April 2021 article for more about bed preparation.)
Peppers should be planted 18-24” apart, in rows 30-36” apart. Dig holes a bit larger than the containers the plants are growing in, and loosen the soil in the bottom of the holes. Gently remove the plants from their pots and loosen their roots a little, especially if they’re very dense. Put one root ball in each hole, deep enough that the first set of leaves is an inch or two above the soil level. (Peppers, like tomatoes, can grow “adventitious” roots out of their stems.) Fill the holes with soil and firmly but gently press it into place. The goal is to ensure good contact between soil and roots without compacting the soil too much. Add a cup of “starter solution” that’s high in phosphorous around the base of each transplant. A general recipe for a starter solution is 4 Tbs. of a 3-10-3 liquid fertilizer diluted in 1 gallon of water. Finally, water the transplants thoroughly.
Plant support, fertilization, and irrigation Domesticated peppers do not have very strong stems, so it’s usually necessary to support the plants. Tie stems to 3’ stakes driven into the soil about 4” from the plant. It’s a good idea to place stakes at the time of planting, to avoid damaging the roots. Another good option is the “Florida weave”, in which twine is run up and down the row, passing back and forth between each plant. Wrap the twine around stakes at the ends of the row and every 3-4’ along the row. (This video shows the process.)
Peppers are fairly light feeders; that is, they do not require much fertilizer as they grow. A little extra nitrogen may be helpful after the first fruits appear if “vegetative growth” (i.e., stems and leaves) isn’t vigorous. Add 3 Tbs. of a 33-0-0 fertilizer per 10 feet of row, 6-8 inches on either side of the plants. Don’t add more than this, or the plants will make too many leaves and not enough flowers and fruit. And be sure to wait until fruits have appeared, for the same reason.
Peppers also have a moderate need for water. Aim for a total of 1 inch of water per week, which works out to about 0.6 gallons or 2.5 quarts per square foot (or 25 liters per square meter). It’s best to keep the moisture level in the soil fairly consistent; that is, don’t let the soil dry out too much.
Mulch will help to keep soil moist. Straw – not hay, which is full of seeds – and grass clippings make great organic mulches. Black or red plastic – the reflected red light stimulates flowering and fruit production – work well also, but can overheat the soil. White plastic may cool the soil a little. Transparent plastic will almost certainly overheat the soil, but might be useful for extending the growing season in colder climates.
Weeds, pests, and diseases Mulch is also an easy way to keep weeds down. Mulched or not, the bed should be kept thoroughly weed-free to avoid competition for water and nutrients. Hand-weeding will work fine for a small area, but a hoe will make the job much easier. A “stirrup hoe” is a great tool for weeding just under the soil, which will avoid damaging the deeper roots of the peppers.
Pests affecting peppers include insects such as aphids, corn earworms, cutworms, and flea beetles, mammals like deer and groundhogs, and root nematodes, which mostly affect bell peppers. The table below details the appearance of these pests, signs of their damage, and a few methods for control. Agricultural extension agents can provide more advice about pesticides and their use.
|aphid||very small, clustered, usually green/black||curled leaves, sooty mold on leaves||pymetrozine, insecticidal soap|
|corn earworm||1″ long, pink-white with dark spots||fruit damage||methoxyfenozide*†, B.t.*|
|cutworm||≥1” long, dark; curl up when disturbed||damaged stems at soil line||paper/foil collars around plant base, methoxyfenozide*†, B.t.*|
|flea beetle||small, dark or striped||many tiny holes in leaves||diatomaceous earth|
|mammals||furry, large or small||clipped leaves and stems||physical barrier|
|root nematodes||very small (≤1 mm)||stunted or wilted plants||resistant varieties|
Always follow the directions on pesticide labels. Also note that even organic pesticides can hurt beneficial insects like butterflies and bees. So be sure to keep products that can be harmful to butterfly larvae, like B.t., away from butterfly habitat. Spray products that are toxic to bees only in the evening, when bees are less active.
The most common diseases affecting peppers are anthracnose, bacterial spot, and tobacco mosaic virus. Prevention via sanitation is the best way to avoid these diseases, which are difficult or impossible to treat once established. Remove and destroy infected plants immediately. Promptly remove fallen leaves, stems etc. during the growing season, and remove all plants and plant debris at the end of the growing season.
Proper growing methods can also prevent disease. Water plants at the base to keep leaves dry, but don’t splash too much dirt onto the plants. Space plants appropriately (18-24” apart in rows 30-36” apart) to promote air circulation. Rotate plantings so peppers aren’t grown where peppers or their relatives, potatoes and tomatoes, were planted the previous year.
These practices can be supplemented by fungicides and bactericides, particularly if neighboring plants are infected. See the table below for details. Agricultural extension agents also are a great source of information regarding chemical disease controls. Always follow the instructions on the labels for both organic and conventional fungicides and bactericides.
Harvest: Peppers have a long growing season. Depending on the species and cultivar, the minimum time for green peppers is about 60 days after planting outside, and can be as long as 90 or even 100 days. Most varieties bear green peppers in 70-80 days. Fully ripe peppers, i.e. red, yellow, or orange, take an additional 2-3 weeks. These times, of course, also depend on temperature and sunlight. The first table above — “Pepper varieties” — lists times after transplanting until green pepper harvest.
Harvest peppers by cutting the stems of the fruit with clippers or scissors. Stems are usually attached firmly to plants, so yanking or twisting can damage fruit and/or plant.
Seed-saving: Seeds from ripe fruits germinate best. If working with hot peppers, wear gloves and eye protection. Harvest the fruit and cut off the top and bottom. Cut the fruit in half and separate the seeds from the placenta. Break up any clusters into individual seeds. Spread the seeds on a smooth surface. Don’t use a paper towel or the seeds may stick or even germinate. Allow the seeds to dry for a few days, or up to a week. Jostle the seeds every day or two to ensure even drying. Carefully running a fan across the seeds may speed things up. The seeds are dry when they are brittle, i.e. when they break when bent.
Keep seeds cool and dry. A sealed jar or plastic tub in the refrigerator is a great option. A desiccant like silica gel may be helpful. Small envelopes or plastic bags can be used to hold seeds from different varieties. It’s also a good idea to note the variety and date on the container. Properly stored, seeds will be viable for two years, though probably not much longer.
For better or worse, saved seeds won’t necessarily yield peppers identical to the parent plant. Peppers self-pollinate well, but cross-pollination is quite possible. And even when self-pollinated, hybrid (i.e. F1) peppers’ seeds usually produce utterly different plants. Open-pollinated cultivars, which includes most “heirloom” peppers, are bred to be the same from generation to generation – when self-pollinated. The rule of thumb is that cultivars should be separated by 300 feet to prevent cross-pollination. Depending on goals and outlook, this can be a problem or an opportunity!
Also a problem and opportunity: healthy pepper plants will yield a lot of fruit, up to 8 lb. per 10-foot row. It’s likely there will be ripe peppers on the plants when frost arrives. Be sure to check out next month’s issue of the Garden Shed for some amazing recipes featuring peppers.
And above all, have fun! Peppers are a delicious, versatile, and nutritious crop with a fascinating history. They’re easy to grow and high yielding, and make a fantastic addition to any home garden.
References and further reading
Photos © 2021 S. Christopher Stroupe and used here with permission
Home Grounds and Animals 2021 Pest Management Guide (Virginia Cooperative Extension), Pest Management Guide 2021/Va.Coop.Ext.
Master Gardeners Handbook: a Guide to Gardening in Virginia (Virginia Cooperative Extension, 2015)
Peppers, the Domesticated Capsicums (Jean Andrews, 1984)
“Growing Peppers in the Home Garden,” ohioline.osu.edu