The flavor of the leaves is strongest just before the flowers open.
Basil is so easy to grow that even if you are a first-time gardener, you can reap bountiful harvests of this annual summer herb. The variety of selections, including several purple-leafed types, makes it a treasured ornamental and culinary herb. Basil's fragrance and taste are unmatched in salads (especially in tomato salads), in vegetables, and in meat and pasta dishes. Since basil is a tender annual, you will need to replant it each spring.
In the Landscape
Basil is a woody, branching herb that will become 2 to 3 feet tall and 2 feet wide, growing quickly as soon as the weather warms in spring. Although its primary place is in an herb garden, some selections are sought after for landscaping as well. Purple basil's deep maroon foliage contrasts handsomely with dianthus, Madagascar periwinkle, petunias, pink cosmos, and yarrow. Fine Green and Spicy Globe are bushy, low-growing, mounding plants with small leaves; they are excellent culinary herbs, but many gardeners also grow them as ornamental bedding plants. They are ideal at the front of a flower border to mask leggy stems and are great for filling holes left by spring bulbs. Because of their compact growth habit, they perform equally as well in containers.
Planting and Care
For best results, plant basil in full sun. In the South, however, basil benefits from afternoon shade. You can buy transplants at garden centers, but basil grows so easily from seed that you may want to grow your own transplants or sow seeds directly in the garden. Basil will not grow in cold soil, so you should wait to start your plants two to four weeks after all danger of frost is past.
Basil likes soil that has a pH of 6.0 and is rich, moist, and well drained. Add a slow-release fertilizer to the soil before or during planting. Plant seeds in a shallow furrow and cover with 1/4 inch of soil. Because basil seeds have a jellylike coating that makes them float easily, be sure to firm the soil to keep them from washing away with the first rain. When plants are 2 to 3 inches tall, thin them to 18 to 24 inches apart.
For an earlier start, sow seeds in flats six weeks before the last frost date in your area. Set transplants out when they are 3 to 4 inches tall, spacing them 18 to 24 inches apart. Basil transplants will not grow much until the days are warmer and longer, but then they will grow rapidly. You can sow them a second time in midsummer.
Basil requires little maintenance--only monthly clipping or pinching back to promote new growth and prevent seedheads from forming. If seeds develop, they will drop and may sprout the following year. After a heavy clipping, fertilize with liquid fertilizer according to label directions. Keep the soil moist, especially after harvesting, as dry soil can stunt growth.
Basil will often cross-pollinate with other selections of basil planted nearby, resulting in seedlings that may not have the same traits as the original plants. If you want your basil to propagate by reseeding, isolate each selection.
You can propagate small-leafed selections from stem cuttings and overwinter them indoors.
Species and Selections
Basil is so productive that you need to start with only one or two plants. You may be tempted to plant many more because basils come in so many popular types.
- Sweet basil (Ocimum basilicum) is the most common basil selection. The plants grow 24 to 30 inches tall with leaves that are about 2 inches long and 1 inch wide. The foliage has a peppery-clove taste and aroma.
- Another common selection, Lettuce-leaf basil (Ocimum basilicum Crispum), has larger leaves (3 to 4 inches long) with smooth edges and crinkled centers. This basil yields abundant foliage.
- Bush basil (Ocimum basilicum Minimum) is a compact type of sweet basil. It grows less than 12 inches tall with leaves that are 1/2 inch long or less. These leaves are excellent when used fresh. Space plants 6 inches apart in the garden. Bush basil also grows well in containers; try named selections such as Fine Green or Spicy Globe.
- Cinnamon basil (Ocimum basilicum Cinnamon) is treasured for the cinnamon aroma of its leaves. Plants grow 12 to 18 inches tall and equally wide. They bear lavender flowers.
- Lemon basil (Ocimum basilicum Citriodorum) grows 18 inches tall and produces light green leaves with a delightful citrus-clove flavor. Lemon basil reseeds easily. Named selections include Mrs. Burns' Lemon Basil, which is more robust and has larger leaves.
- Purple basil comes in several selections. Purple Ruffles (Ocimum basilicum Purple Ruffles) and Dark Opal (Ocimum basilicum Purpurascens) are selections of sweet basil with large maroon to purplish leaves and lavender blossoms. Their scent and flavor are not as sweet as those of other basils. But when the leaves are added to white vinegar, they turn the vinegar pink. A dwarf selection of Purple Ruffles is also available. It is popular for adding foliage color to flower gardens. Plant this basil in partial shade.
- Thai basil (Ocimum basilicum Siam Queen) is an All-America selections winner prized for its ability to yield a good harvest and its tendency to flower later than other basils. It grows 2 to 3 feet tall and about 2 feet wide.
Harvest, Storage, and Use
When you want to use basil fresh from the garden, cut the tips of the stems as you need the leaves. Wait until young plants grow to at least 6 inches tall; this will encourage branching. To extend the life of the plants, pinch off the flower buds as they appear in July and August. If you do not pinch off the flowers, the plant will stop producing new leaves. You should be able to make several harvests in one season before frost kills the plants. If you allow a plant to become covered with seedheads, clip them off and use the leaves to make a basil wreath.
Basil can be dried, as can most herbs, with some of its aroma preserved. However, its flavor is best preserved by freezing or by storing the leaves in vinegars or refrigerated oils. Handle leaves gingerly, or they will bruise and blacken. Harvest basil just before the flower buds are ready to open; clip the plant back to one-third its original size.
Use fresh basil in soups, pasta dishes, and pesto and with cucumbers, eggs, and shrimp. To benefit from basil's full flavor, add it during the last 10 minutes of cooking. For an interesting garnish, add strips of sliced basil leaves to canned soups or stews just before serving. Basil blends well with oregano, parsley, rosemary, sage, and thyme.
Keep basil healthy with regular pruning to remove flowers and seedheads. When cutting, be careful not to cut back to the woody stem, or the plant may not recover. Basil is occasionally bothered by slugs or Japanese beetles.