How to Grow Jalapeño Peppers

The jalapeño pepper is a chili-type cultivar of the Capsicum annuum species, a species that also includes sweet bell, habanero, and cayenne peppers. Jalapeño falls in the middle of the pack in terms of spiciness, with a medium-hot punch. These peppers have the same cultural needs as other cultivars of the species, but they are typically harvested while the pod-shaped fruits are still green. If left on the plant, the fruits will ripen to a red, orange, or yellow color.

Jalapeño peppers are planted in the spring after all danger of frost has passed from nursery starts or from seeds started indoors. They have a fast growth rate, taking three to four months from germination to produce fruits that can be harvested. Be aware that the leaves and fruits of jalapeño plants contain capsaicin, a compound that creates a burning sensation and can be toxic to both people and pets.

How to Plant Jalapeño Peppers

When to Plant

The peppers need warmth to germinate, so seeds should be planted in the garden after soil temperatures reach at least 65 degrees Fahrenheit. You also can start seeds indoors around eight to 10 weeks before your area's last projected frost date. Young plants can be transplanted into the garden once nighttime temperatures are reliably above 60 degrees Fahrenheit. Because peppers need warmth to germinate, most gardeners in colder climates with short seasons begin peppers from seed indoors or purchase transplants. Direct sowing seeds in the garden can be challenging.

Selecting a Planting Site

These plants need a sunny location to grow well and bear lots of fruit. They can grow in the ground or in containers. The soil should be organically rich and have sharp drainage. Try to keep your jalapeños away from other members of the nightshade (Solanaceae) family, including tomatoes, as they can transmit diseases to one another. Similar pests also can infest all members of the nightshade family.

Spacing, Depth, and Support

Space the plants about 14 to 16 inches apart, and leave about 2 to 3 feet between rows. Nursery plants should be situated at the same depth they were growing in their containers. Cover seeds with about 1/4 inch of soil. Jalapeños usually won't need a support structure, though some of the taller varieties might need stakes to prevent their fruits from weighing them down.

Jalapeño Pepper Care

Light

Plant jalapeño peppers in full sun, meaning at least six hours of direct sunlight on most days. While they will tolerate a bit of shade, the plants will be spindly and the fruit production will diminish.

Soil

The ideal soil for jalapeño peppers is fertile, moist, and well-drained. A slightly acidic to neutral soil pH is best. The peppers don't do well in dense, soggy soil. If growing peppers in containers, any rich, general-purpose potting mix that drains well should be sufficient.

Water

Unlike some other members of the nightshade family, jalapeño peppers need lots of water. Water them when the soil feels dry about an inch down, but don't allow the soil to become waterlogged. A thick layer of mulch will help to conserve soil moisture.

Temperature and Humidity

Jalapeños prefer temperatures between 65 and 85 degrees Fahrenheit during the day and 60 to 70 degrees Fahrenheit at night. Colder temperatures, along with persistent temperatures above 90 degrees Fahrenheit, can cause the blossoms to drop and thus minimize fruiting. A moderate humidity level is ideal for these plants.

Fertilizer

Peppers are heavy feeders. If you've amended the soil with good, rich compost, your plants should be happy and produce well. However, they will still benefit from additional side dressing of compost or a balanced fertilizer throughout the growing season for maximum productivity. Peppers growing in poor soil or in containers will benefit from an application of a balanced granular fertilizer or a layer of compost around the base of the plant as blossoms begin to form.

Pollination

Jalapeño plants self-pollinate with the help of wind and pollinating animals, and they also can cross-pollinate with other pepper species. To aid in pollination, especially when growing your plant indoors away from pollinators, gently shake your plant every few days to distribute the pollen. 

Types of Jalapeño Peppers

Over time, breeders have introduced a number of pepper varieties. Jalapeño peppers vary in size, color, and the amount of heat they provide. Some popular varieties include:

• 'Seniorita' ripens to a dark green that turns purple and then red. The peppers are about 3 inches long and are fairly hot. It takes 80 days for them to mature from seed to harvest, and the plants grow about 2 feet tall.
• 'Fresno Chile' produces smaller, 2-inch peppers with mild heat.
• 'Sierra Fuego' is a hybrid variety that produces mildly hot 3.5-inch peppers. It matures in about 80 days.
• 'Mucho Nacho' matures quickly in about 68 days. The peppers are 4 inches long and relatively mild in taste.

Jalapeño vs. Serrano Peppers

Serrano peppers also are a variety within the Capsicum annuum species. Jalapeño and serrano peppers are similar in appearance and flavor. Serranos are generally slightly smaller. But the real difference between the two varieties is their heat. Serranos pack approximately five times more heat into their fruits than jalapeños do.

Harvesting Jalapeño Peppers

As they ripen, jalapeño peppers transform from light green to glossy dark green and then to red, orange, or yellow. For maximum heat, they should be harvested when they are full size (usually around 4 inches) and dark green—before they turn red/orange/yellow. If left on the plant to fully ripen, the peppers will be sweeter but still hot and tasty. Snip off the peppers with pruners, leaving a bit of stem on each fruit. Do not pull fruit off plants, as you may break fragile stems.

The peppers won't survive even a hint of frost. So if temperatures below 35 degrees Fahrenheit are predicted, you should harvest all remaining peppers and continue to ripen them indoors by placing them by a bright window. If you're growing in a container, you can move the entire container indoors to continue growing.

The peppers can be eaten fresh or cooked. Store them unwashed in a loosely covered container in the refrigerator, where they’ll stay fresh for around a week. You also can freeze peppers, as well as dry them, for later use.

How to Grow Jalapeños in Pots

Jalapeño peppers grow well in containers. A 3-gallon container is ideal, though they can survive in something smaller but will likely have a lower production. Be sure the container has ample drainage holes. An unglazed clay pot is ideal because it will allow excess soil moisture to escape through its walls. Use a quality potting mix that drains well, and situate the plant in your container at the same depth it was growing in its previous pot. Water after planting.

Container growth allows you to move your plants around to give them optimal sunlight. Plus, you can bring them indoors during cold weather to continue growing, provided that you can supply them with enough light. Because frequent watering of containers leeches nutrients from the soil, use a liquid fertilizer as directed to keep plants healthy and productive.

Pruning

Jalapeño plants generally won't need pruning. But if you see suckers popping up around the base of the plant, trim them off. This will allow the plant to put its energy into the main stems that will produce the most fruits.

Propagating Jalapeños

Jalapeño plants are commonly grown from seeds or nursery plants. But they also can be propagated via cuttings. This is an inexpensive way to get a new plant, and it allows you to essentially clone a particular plant with especially good fruit production. The best time to take a cutting is in the early summer. Here’s how:

1. Cut a healthy piece of stem that’s between 4 to 6 inches long. Cut at a 45-degree angle just below a leaf node. 
2. Remove any leaves on the lower half of the cutting. Also, remove any flowers or fruits. 
3. Dip the cut end in a rooting hormone. 
4. Plant the cutting in a moist soilless potting mix. Use a small container that has drainage holes. 
5. Keep the cutting in a warm spot, roughly 70 degrees Fahrenheit, and put it in bright, indirect light. 
6. Roots should form in about two weeks. Gently tug the stem; you’ll know roots have grown if there’s resistance. Then, the cutting is ready for transplanting.

How to Grow Jalapeños From Seed

Start seeds indoors in a tray filled with moist seed-starting mix around eight to 10 weeks before your projected last frost date. Expose the tray to 16 hours of artificial light during the germination period, and make sure the soil remains between 65 and 80 degrees Fahrenheit. A seedling heating mat can help control the temperature. Germination can take two to three weeks. Continue to keep the soil moist for the seedlings. When the seedlings have two sets of true leaves, pot up into a larger container with potting soil. Once they are 6 to 8 inches tall, they can be hardened off, gradually exposed to outdoor conditions, for two weeks and then planted in the garden.

Overwintering

If you wish to keep your jalapeño plant over the winter, pot it up in a container to bring indoors prior to any threat of frost in the forecast. Keep it by a bright window, preferably a south-facing one. And protect it from drafts, as well as dry air from heating vents. Water whenever the top inch of soil dries out. Pinch back the stems if the plant starts to get leggy due to lack of light.

Common Pests and Plant Diseases

Like most vegetables, jalapeño peppers are susceptible to a variety of insect pests and disease issues. Many of them are common to other members of the nightshade family. They include:

• Aphids are one of the most common pepper pests. These tiny green or white insects suck the sap from the leaves, reducing the vigor of the plant and making it more susceptible to diseases. If possible, use a nontoxic control method, such as predatory insects like ladybugs or insecticidal soaps.
• Cucumber beetle larvae can damage the roots of young plants. These small yellow-green beetles with black stripes eat holes in the leaves. Keeping the area free of weeds will help to eliminate the beetle breeding areas.
• Pepper hornworms are greenish caterpillars that chew large holes in the leaves. The best remedy is to pick off the worms by hand.
• Mites are nearly invisible insects that cause distortion or discoloration of the leaves. Affected plants should be removed and destroyed.
• Fusarium wilt is a fungal disease that causes plants to weaken and turn yellow. Affected plants will need to be removed and destroyed. Keeping plants healthy and well-watered usually prevents this disease.
• Anthracnose is another common fungal disease, creating dark sunken spots on the fruit. Remove and destroy affected plants, and make sure to buy resistant varieties when you next plant.