The jalapeno pepper is without question one of the most important and common of the hot peppers. Hailing from Mexico, jalapeno peppers are not terribly difficult to grow and pack a medium-hot punch (on the Scoville scale, they range up to about 30,000 Scoville units for very hot varieties, while a habanero pepper can get as high as 800,000 Scoville units). They are typically grown outside during the summers and springs, but for people in unsuitable climates or who don't have access to a vegetable garden, they can be successfully grown indoors.

The trick to growing jalapeno indoors is to give the plants plenty of room to grow, have a careful hand with the watering, and give the plant enough light to flower and bear fruit. Although you can do well growing them in sunny, south-facing windowsill, there's no question you'll do better with the right lights.

Growing Conditions

• Light: Peppers need a considerable amount of light to do well. Seedlings are best grown under lights, with 16 hours of light daily until they have put out two or three sets of true leaves. Once the plants have been potted into their final homes, they should get 4 hours of full sun daily at a minimum, and more is better.
• Water: Jalapeno need a steady supply of water but should never be kept water-logged and try to avoid letting the leaves get too wet.
• Soil: Any good, fast-draining potting soil will likely do.
• Fertilizer: Feed with a weak liquid vegetable fertilizer throughout the growing season.  

Propagation

Jalapeno can be started from seed or from seedlings purchased at your local garden center.

If you're buying seedlings, try to buy plants that have not yet begun to fruit. To start from seeds, sow seeds in sterile seed-starting soil and keep them warm and moist until they emerge. Seedlings can be fragile, so be careful not to overwater and provide plenty of light.

Repotting

Jalapeno should be repotted once they've put out a few sets of true leaves. The mature plants are 24 inches or taller, so plant into a large enough container to hold the mature plant. I'd recommend going with at least a 1-gallon pot (although really, that's too small for optimum growth). If you have room for it, a 3-gallon container is best.

Varieties

Over time, breeders have introduced a number of varieties of the popular jalapeno pepper. All peppers belong in the species Capsicum annum, so the differences attributed to each pepper are mainly regarding appearance and heat. Jalapeno peppers vary in the amount of heat they provide, their size, and their color (there are white and purple jalapeno varieties, in addition to the common green/red peppers).

Grower's Tips

Growing the jalapeno plant is only part of the equation—the other important issue is knowing when to harvest. Like sweet bell peppers, jalapeno can be harvested green or red. Most people prefer green jalapeno, so harvest your fruit when they are large and firm and still green. They might naturally redden somewhat after harvesting, but that's OK and won't affect their color. When you harvest the peppers, it's best to cut them from the plant to prevent damaging the fruit. In terms of diseases and pests, the plants are fairly tough, but there are definitely known to have some pest issues, both indoors and out. Jalapeno plants are vulnerable to pests including aphids, mealy bugs, scale, and white fly. If possible, identify the infestation as early as possible and treat with the least toxic option.