Peppers are related to tomatoes and tomatillos and have similar structures and form. The plants grow 18 to 24 inches high, depending on the variety, and have one strong central stem with horizontal branches that produce fruit and flowers. A strong, deep root system is critical for good fruit production.
Most gardeners buy nursery transplants or start seeds indoors. When the young pepper transplants are set out in early summer, their root system encompasses the entire pot, usually 3 to 4 inches. By the end of the season, the pepper's roots may extend 8 to 12 inches deep and at least as wide, but they remain fairly fine. Pepper's roots are deeper than the roots of lettuce, broccoli or spinach, but remain fairly close to the surface.
Good growing conditions develop strong, deep roots. Wait until at least two weeks after the last frost before planting peppers and lay black plastic over the soil to warm it. Plant peppers when daytime temperatures are between 70 and 80 degrees Fahrenheit. Planting peppers too early in the season results in stunted roots and leaves, and even deformed fruit or reduced yields. Space the peppers 18 inches apart so roots have room to grow. Apply a low-nitrogen, high-phosphorus fertilizer, such as a 5-10-10 formula immediately after planting to establish strong roots. Water the plants as needed to keep the soil evenly moist.
Pull weeds by hand or cultivate them very shallowly with a hoe. The roots of pepper plants lie near the soil surface and are easily damaged by deep cultivation. Better yet, mulch pepper plants with thin layers of dried grass clippings or straw to reduce weed growth and prevent damage by weeding.
Peppers aren't particularly fussy about soil types, but the soil must be well-drained. In heavy, wet soils, peppers are prone to rotting roots and other diseases. Blossom-end rot may affect pepper fruits, causing the bottoms of the fruits to turn black. Prevent this disease by cultivating shallowly to avoid damaging the roots. Water the plants evenly and consistently, and add lime to the soil every two or three years if the soil is alkaline.