The Facts about Basil Plants

Appearance and Propagation

• Sweet basil plants grow about 20 inches tall and spread 12 inches wide, if given the room to grow. Potted basil plants remain compact unless moved to a larger container. Basil seeds grow when planted straight into the ground at 1/4-inch depth after the local frost-free date. To start the growing early and help the plant survive any late cold spells, try indoor propagation in small pots. Seedlings appear a week after planting.

Growing Conditions

• Basil prefers warm, sunny locations and doesn't tolerate sharp frosts or long spells of cold weather. The plants thrive in light soil that doesn't hold water too long; heavy soil can choke the roots. Horticulture specialist Jill MacKenzie of the University of Minnesota Extension suggests a soil pH range of 6.0 to 7.5. Basil can grow outdoors in summer in most of the U.S. But it also grows well in small pots left on a sunny windowsill. It rarely survives winter outdoors, except in hot Southern states.

Care

• The BBC Plant Finder suggests watering basil before midday to ensure the surface water evaporates before evening. Water left on the delicate leaves can cause problems with rot and withering. Water the soil, not the foliage. Outdoor basil plants may benefit from a 2-inch layer of straw or leaf mulch to help suppress weeds and keep the ground damp. Horticulture agent Gene McAvoy of the University of Florida Extension recommends using complete fertilizer such as 6-6-6 or 8-8-8 in doses of half a pound per 25 square feet.

Varieties

• Though sweet basil remains the most common in gardens and on windowsills, many other varieties are available. For example, Thai basil has a stronger flavor and deeper color -- almost purple on some plants. It contains a little more heat and spice than sweet basil. Lettuce leaf basil is sweeter than both Thai and common basil, with larger, wrinkled leaves. Some varieties, such as the purple-leaved opal basil, are better suited to ornamental gardens than for use in the kitchen.