Growing Chile Peppers - Brooklyn Botanic Garden
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Growing Chile Peppers

Chile peppers evoke thoughts of spicy foods from hot places—dishes from the Southwest, Mexico, China, India, and Southeast Asia. Perhaps for this reason, many people mistakenly think that the only part of North America where chile peppers will grow is the hot and arid Southwest. But you can grow chile peppers just about anywhere in the United States and southern Canada, as long as you prepare your soil, nurture your seedlings properly, and provide the plants with their basic needs.

The Quiet Winter Months

Mulch your chile plants to control weeds and retain water.
Mulch your chile plants to control weeds and retain water. (Photo: Susan Belsinger)

Long before you pop your first plant into the ground, you should make a garden plan. You can either grow chiles from seed or buy potted plants closer to planting time. The payoff for using seed is the abundance of varieties—many of them rare and exotic—that seed companies offer. (See "Seed Sources," page 98.) If you decide to grow your chiles from seed, you should start germinating and tending seedlings in the early spring.

If you decide not to grow chiles from seed, you can buy potted plants in the spring from a local garden center or specialty grower. Bear in mind that most garden centers have quite limited selections—often only one to three varieties at most. Specialty growers sell many more varieties of chile pepper plants, but these are often quite expensive.

Not all varieties do well in every region, so select those that grow best where you live (see "Encyclopedia of Chiles," page 68). But don't be afraid to experiment with offbeat varieties just for the fun of it.

Hot Chiles For Cool Climates

These chiles are recommended for areas with short growing seasons:

  • 'Hungarian Yellow Wax'
  • 'Jalapa Jalapeño'
  • 'Long Slim Cayenne'
  • Superchile hybrid
  • 'Early Jalapeño'
  • Anaheim
  • Ornamentals
  • 'Mulato Isleno'

—Susan Belsinger

When choosing among chile pepper varieties, keep the following additional factors in mind:

The maturity date for each variety. If you live in a cool, northern climate, your growing season is short, so choose early-maturing varieties. The prolific 'Hungarian Yellow Wax', maturing in 65 days, is a good choice for northern gardens. 'Aci Sivri', an heirloom pepper from Turkey, takes 90 days to mature but fruits abundantly in northern gardens. In contrast, ancho, Anaheim, and chilaca bear quite profusely in the arid Southwest after 90 to 120 days, but do poorly in northern climates.

The humidity in your area. Peppers are sensitive to humidity. Jalapeño, cayenne, and mirasol all prefer arid climates, while habanero, Scotch bonnet, and datil prefer humid surroundings.

How you will use your peppers. Peppers can be eaten raw or prepared in a variety of ways: stuffed with meat or cheese, dried, or pickled. The best peppers for stuffing are large and have thick flesh; poblanos are a good choice and grow especially well in the Southwest. Many of the smaller, thin-fleshed chiles, such as chiltepin, can be dried in the sun, even in climates that lean toward the humid. Any chile pepper can be pickled; jalapeño and pepperoncini are two of the most popular peppers for pickling.

The number of plants you will need. This depends on how many you think you will eat or store. As a rule of thumb, five to six plants of each variety you desire should be more than enough to satisfy a family of four. But find out how much fruit your varieties produce. A single serrano plant can produce up to 50 fruits. Manzano and rocoto will probably bear only a few immature fruits in the Northeast, as they require a long, cool growing season at higher altitudes. In general, the varieties that bear small fruits tend to be quite prolific and take less time to mature. A few Thai hot plants, which bear an abundance of small, bullet-shaped fruits, go a long way.

The level of pungency you desire or can handle. The pungency of the different chile pepper varieties is rated in different ways. The simplest rating method is a heat scale of 1 to 10, from mildest to hottest. Pepperoncinis, often used in pickled Italian salads, have little or no heat. The habanero, on the other hand, scores a 10 and is generally considered the world's hottest pepper.

In the "Encyclopedia of Chiles," pages 68 through 97, you'll find detailed descriptions of 57 chile peppers, their preferred growing conditions, heat levels, and tips on how to best grow them. You can also consult "Resources," pages 102 to 104, and seed catalogs. County Extension agents, garden clubs, botanic gardens, and horticultural societies often provide specific regional information.

Germinating Chile Seeds

The Right Start

Chile pepper seed will germinate best under the following conditions:

  • Air temperature of 70 to 80°F
  • Bottom heating at 75°F—heated cables work well
  • Sterile potting medium
  • Good air circulation
  • Strong light source
  • Proper watering with warm water

Gardeners in most regions should sow seeds 6 to 8 weeks before the last frost. In colder climates, however, you can sow your seed 8 to 10 weeks before the last frost. And if you live in a warm area with a long growing season, you can sow the seed directly into the garden, 1/4 inch deep, once the soil has warmed to 75°F.

Certain varieties of chile peppers have a seed-coat dormancy and require a treatment to soften the seed coat prior to planting. For example, chiltepins, wild peppers from the Southwest and Mexico, often have a seed-coat dormancy. To soften the coat, soak seed 5 minutes in a 10-percent bleach solution and then rinse. Alternatively, you can soak seeds for 4 hours in a solution of 1 teaspoon saltpeter (potassium nitrate) per 1 quart of water.

Since most chile peppers are tropical plants, if you don't live in a warm region with a long growing season, you'll have to replicate the tropics. (See "The Right Start") For most gardeners—those who don't have a heated greenhouse—the best place to start chiles is in a cold frame. Put a thermometer into the cold frame, and if it gets hotter than 80°F, prop open the glass cover. You can also use a heating coil, if necessary, but it's likely that the sun will provide enough warmth.

Fluorescent light stands are another good option for starting pepper plants. However, a sunny window is not a good place to grow seedlings—it is very difficult and should be a last resort.

The potting medium should be light and well drained. Peppers will not tolerate soggy conditions at any stage of their growth. Plastic trays or small peat pots make good containers. When you are ready to sow, first moisten your soil mix, then plant the seed 1/4 inch deep. (Remember to label your peppers according to variety). Water well, and the seed should germinate in about 10 days. To help prevent diseases, keep the above-ground portion of the seedlings somewhat dry.

When your seedlings put out their second set of leaves, transplant them into larger pots. If you started plants in peat pots, they may remain until planted out. A liquid fertilizer designed for seedlings will give plants a boost; always follow the instructions on the label. As seedlings mature, they will need a little less heat, but watering, air circulation, and lighting must be optimal.

Once the last frost date for your region has passed, you can harden off your plants by moving them outside for longer intervals each day. Start by taking them out for a few hours in a shady location, then build up to longer periods in a partly sunny spot. Do this for one to two weeks, bringing plants indoors at night in the early stages. Beware of windy days and intruders such as cats, which can ruin a crop.

Preparing the Site

Growing Chiles North to South

Chiles like long, hot days and warm nights. They need warmth and light for germination and early growth, and they flower and set fruit best when days are 8 to 12 hours long and nighttime temperatures are 60° to 70°F. Because they're sun worshippers that like moist soil, planting out chiles can be a bit of a balancing act, especially in the northern regions of the United States and in Canada.

For some general rules of thumb for growing chiles, it is helpful to divide the country into three regions based on frost-free dates and USDA Hardiness Zones (see map, page 106).

THE NORTHERN TIER encompasses Zones 3, 4, and 5. The dates for the last spring frost here have the longest range, from the beginning of May until the end of June. Select chile varieties that mature and fruit within 75 to 80 days (see "Hot Chiles for Cool Climates").

Since the growing season is short, you need to ensure that your plants have maximum garden time so that they can mature before warm weather ends. Germinate seed indoors about 40 days before you want to transplant the chiles outdoors; they should be just about ready to flower when it is time to set them out. Alternatively, you can buy plants that are already well established.

About two weeks before planting, cover the beds with clear plastic mulch to warm the soil. Harden off the chiles for two weeks. If necessary, plants can be set out early and protected from frost overnight with plastic milk jugs or bottles; remove them each morning. However, it is better to wait until the garden soil is warm, not cold, so that the plants suffer less stress.

Mulching your peppers with black plastic, black mesh, or heavy straw will help the soil retain moisture, keep down the weeds, and reflect sunlight onto the plants, giving them more heat and light.

If cool temperatures come early and your chiles have not yet matured, cover them before dusk with Reemay, lightweight tarps, or even bedsheets. Remove the nighttime covers in the morning before the sun shines too hot and creates an oven beneath the covers.

THE CENTRAL TIER covers Zones 6 and 7. You should have your chile plants ready to set out shortly after the last frost date—early April through mid-May. You can plant them at the same time as you set out basil and tomatoes, when the ground is warming up. If the weather is cold—especially if it's wet and rainy—wait to transplant chiles; otherwise, you risk damping off.

In areas of the Central Tier where the soil needs help retaining heat and moisture, it is a good idea to mulch your plants. If all of the fruits are not yet mature at harvest time, you may have to cover your chile plants to protect them from an early fall frost (see above).

THE SOUTHERN TIER includes Zones 8, 9, and 10. This part of the United States is where chiles grow best. The last spring frost in this region occurs sometime during early February to the end of March. As the growing season is long, there is no need to rush the plants into the ground until after the soil has warmed up. Even the peppers that take longest to produce fruit have plenty of time to mature.

The most important thing to watch out for is summer stress during times of high temperature or drought. You needn't be overly vigilant, though—chiles are pretty tough. Just be sure to water and fertilize transplants early on, so that they will be well established before the really hot weather arrives. And bear in mind that if night temperatures are above 86°F, fruit set will not occur.

—Susan Belsinger

Before transplanting, it's wise to improve your soil. Humus—thoroughly decayed organic matter—is rich with nutrients that pepper plants need and will also help the soil retain moisture. Supplement your soil with organic matter, especially well-rotted compost, and your plants will become lush and provide you with many more fruits than if you had not amended the soil.

Test your soil to determine its pH. Peppers do best in soil with a pH between 6.0 and 8.0. If the pH is below 6.0, add ground limestone, following the rate of application on the bag. If the pH is above 8.0, you can add peat moss to lower the pH. Thoroughly mix these amendments into the soil.

Plant the peppers in a site that receives full sun at least 6 hours per day. Like most vegetables, peppers will not yield well in a shady location. (One exception is the chiltepin, which is shaded by boulders and the mesquite plant in its native desert areas.)

Choose a site that is protected from high winds, as pepper plants tend to be somewhat brittle. Don't plant them in a plot where you've previously grown members of the Solanaceae or nightshade family—peppers, eggplants, tomatoes, tobacco, potatoes, and petunias—or plants in the Rosaceae or rose family, especially brambles such as blackberries and raspberries. All of these plants can harbor diseases such as verticillium wilt, which infect the soil and then your peppers.

No matter where you live, make sure that your soil is well drained, since peppers will not survive in wet soils. Your planting bed should be level so that the soil has good drainage and water won't pool in depressions. Raised beds work well, but because the soil in them dries out quickly, they're best in areas with good irrigation to offset dry periods, or in wetter climates such as the Northeast. In arid regions, sunken beds work well; place plants in furrows between ridges of soil, where water will collect.

Transplanting Your Seedlings

Whether you bought them or grew them from seed, the plants you put in the garden should be sturdy and have many deep green leaves. Plant them after the last frost date, when daytime temperatures are at least 65° and night temperatures above 55°F. Temperatures any lower will weaken plants, making them susceptible to pest problems and environmental stresses. To give plants good air circulation and room to expand, space them 11/2 to 2 feet apart, in rows that are 2 feet apart. Make sure you've properly labeled the different varieties.

Dig a hole a bit wider and deeper than the pot. If you germinated the seed in peat pots, carefully break open the bottom to promote downward root growth. If your plants are in plastic pots, pop out the root ball and gently spread the roots. Put the peat pot or rootball in the hole and fill with soil. The plant's stem should be a bit below the level of the ground. If the plant is elongated and spindly, plant it deeper or sideways and cover a portion of the stem. Rake the planting bed to level out depressions that could trap water.

The most critical factor after transplanting is watering! Water gently and soak the planting bed well, preferably with a hand-held hose. The first few weeks are critical, so water at least daily to ensure that the soil stays moist. Look for wilted plants; this is usually a sign that they need more water, although in some cases they've received too much water. Check the soil. If it's very dry to the touch, increase watering. If your plants are wilting in soggy or saturated soil, either you are overwatering or your plant is suffering from a soilborne disease. (See "Pests and Diseases of Chiles," page 41.)

If you have rich, humusy soil, you may not need to fertilize. Otherwise, you can feed plants with a liquid fertilizer such as 10-55-10 beginning a few weeks after transplanting, and up to once a month during the growing season. Healthy plants are deep green and will begin to flower a week or two after transplanting.

Weeds will undoubtedly sprout among your peppers, and if they remain, they will soon choke out the crop. Cultivate the bed lightly each day, removing all the weeds. Continue watering, and apply a mulch to the soil to keep down weeds and help retain valuable moisture. Use an organic mulch such as straw, wood chips, or pine needles. Cover all soil areas with mulch about 2 inches deep, but don't let the mulch touch the stems of the plants. Use thinner layers in the arid Southwest, where the mulch will not break down as rapidly. You can also use an inorganic mulch, such as black plastic. This is probably the most efficient mulch for weed control, but it absorbs tremendous amounts of heat and makes watering difficult.

Maintaining the Plants

Small, compact pepper plants or low-growing ornamental types seldom need staking. However, some plants are taller and bushlike, such as jalapeant ancho, New Mexican, and Capsicum baccatum varieties. These plants tend to sprawl due to their height, branching pattern, and fruit load, and will fall over, snap, and touch the soil if unstaked. When they begin to sprawl, support them with slender bamboo stakes a bit taller than the plants. Drive three stakes into the ground around the plant, equally distant from each other. Tie garden twine horizontally around the stakes and plant, knotting only to the stakes. Make sure the twine has enough play to support the plant without constricting its growth. If the plants start to look confined, insert a new set of stakes farther from the plants, then carefully undo the original construction.

Chile peppers will often put out shoots that can become leggy. You can cut back the shoots to make the plants grow in a more compact manner. One month after transplanting or after you've staked those plants that need it, remove 4 to 6 inches from all leggy stems with hand shears or scissors, or by simply pinching them off between thumb and forefinger.

Continue watering, but do so less frequently than when the plants were young. Let the soil get a bit dry between waterings; this will help your plants become acclimated to the more adverse conditions. Here in the Northeast, I water no more than twice a week, depending on rainfall. I give the plants a good soaking; in this region, 20 minutes per watering is sufficient. Your plants may show signs of wilting on hot afternoons, but they'll usually recover by the following day if you have taken care of them all along. If you live in an arid climate, you'll have to water more often and more deeply, as your plants will transpire more profusely.

As your chile plants become more established, hold back on watering once in a while. Your plants may suffer a bit but the fruits will become more pungent—because you've stressed your plants, they bite you back more sharply!

Flowering starts as the plants begin to form branches. Peppers are pollinated primarily by bees, which encourage cross-pollination. The resulting fruit will be true to the variety, but its seed will be hybrids, having genetic traits from both parents.

Peppers are generally pest-free if you follow good cultural practices. Don't water at night or let the fruits touch the soil, which can harbor disease and pests. If the weather turns very wet, soft rot can infect your plants and cause the fruits to turn to mush. When the weather dries up, your plants usually will improve. Remove any diseased fruits from the garden; don't put them in the compost pile. If you find aphids feeding on the succulent pepper stems, all it takes is a stream of water to knock them off. (See "Pests and Diseases of Chiles," page 41.)

If, early in the season, you leave fruits to develop on plants, you are likely to reduce further flower production. The plant will achieve its ultimate fruit load before you have reached your ultimate harvest. I usually remove as many fruits as possible during the first couple of months after transplanting and then, as the season progresses, I remove larger reddening fruits as needed. Do not leave fruits on your plants past their ripe stage; they are an invitation to diseases such as anthracnose.

Harvesting Chiles

You can harvest peppers at any time, but generally, when a fruit reaches its ultimate size, it's ready to be harvested. (See "Encyclopedia of Chiles," page 68, and seed catalogs for the maximum size for each variety.) Green peppers are simply unripe; they have a particular flavor that some people prefer. Red peppers are ripe and usually have a fruitier taste. Peppers reach their hottest stage when they are between green and red (or bright orange, in the case of habaneros and Scotch bonnets).

If your peppers don't easily pull free from the plants—and most green peppers won't—simply cut them off using hand clippers or scissors, including as much of the fruit stem as possible. This is especially important if you're storing them.

In the fall, if there is a threat of frost, harvest all peppers regardless of their size, as frost will turn them to mush.

No matter where you live, to ensure continuous flowering and fruiting and to encourage large yields, harvest the first green peppers as soon as they are fully developed. These usually are not as large or hot as end-of-season peppers. Cut the stems about 1/2 inch above the pepper caps; branches, especially when they are chile-laden, snap easily. A mature pepper is evenly colored and feels firm. Mature green chile peppers are very good eating; Anaheims and other long green chiles are marketed at this stage. But harvesting a few immature peppers from your garden early is better than having a meager harvest at the end of the season.

Whatever the climate, with good cultivation practices and continuous harvesting, pepper production can last from one to three months after the first harvest. Chiles left on the plant will ripen from green to other colors progressively, showing a rainbow of colors on the same plant. When the chiles ripen to orange, red, or mahogany, they have the fullest flavor and the most pungency.

One final note about harvesting: The "hot" part of the pepper, the capsaicinoids, can burn your skin, especially if you have open cuts. And, the oils (capsaicids) can burn your eyes if you rub them with your fingers. It's best to wear rubber gloves when harvesting, especially if you're sensitive to the oils. The best antidote for burning hands is to rub them with isopropyl (rubbing) alcohol, as the oil is soluble in alcohol.

Doug Dudgeon is the assistant horticulturist at the Dawes Arboretum in Newark, Ohio. For nearly 14 years, until early 1999, he worked at the Brooklyn Botanic Garden, where he was in charge of the chile pepper collection, the Japanese Hill-and-Pond Garden, the Fragrance Garden, and the Shakespeare Garden.

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Image, top of page: Antonio M. Rosario