Although the different varieties of basil vary in size and flavor, care of the plants is the same.
In the Garden
A woody, branching plant, basil is a warm-weather annual that grows very fast in 80- to 90-degree weather. Two or three plants yield plenty of fresh basil for a family of four unless you plan to make pesto. To make and freeze a winter’s supply of pesto, plant a dozen or more. Many gardeners mix various types of basil in their flower beds, where it is ready for a quick harvest anytime. It is also great for containers.
Soil, Planting, and Care
You can grow a lot of basil in a vegetable garden, where it is handy for a big harvest to make pesto. This is sweet basil.
Basil needs 6 to 8 hours of sun; in the South and Southwest, it benefits from afternoon shade. Set out plants at least 2 weeks after the last frost in spring; summer planting is okay, too. Space at the distance recommended on the label, which is generally 12 to 18 inches apart. Plants are very frost sensitive, so keep plants protected in case of a late cold spell. Basil likes rich, moist, but well-drained soil with a pH of 6 to 7. Because basil is harvested continually for lots of leaves, it needs a little fertilizer. When planting, add plenty of organic nutrients from compost, blood meal, or cottonseed meal to the soil. Feed with Bonnie Herb & Vegetable Plant Food every couple of weeks to help keep tender new leaves coming on as you pinch back the stem tips.
If planting in a container, use a large pot to keep the plants from drying out quickly in hot weather. You may also want to add a water-retaining polymer to the potting soil to keep the soil evenly moist and extend the time between waterings.
Basil wants to bloom as summer progresses. To keep the plant lush, pinch off the bloom stems as they appear. This Thai basil has purple blooms.
Occasionally, basil is bothered by aphids, slugs, or Japanese beetles. However, the biggest threat is poor drainage, so to avoid root rot, plant in a well-drained location. Also, don’t let it get too dry, or growth may be stunted. If your plants get away from you to the point at which they are making seeds and have stopped growing, shear off the top third of the stems and fertilize with liquid fertilizer. Never cut the woody part of the stem, or the plant won’t sprout back.
Harvest and Storage
Basil can be a beautiful addition to the garden and landscape. This pot of purple basil provides height, color, and flavor in a patio-side garden bed.
Harvest basil leaves by pinching them from the stems anytime after the young plants have reached a height of 6 to 8 inches. Pinch the leaves from the tips of the stems to encourage the plant to branch and make more leaves. Try to keep the stems pinched even if you don’t use the leaves; otherwise, the plant will begin to flower and make seeds, and will stop producing leaves. At the first prediction of even the lightest frost, go ahead and harvest all your basil because it will quickly turn black in cold weather. Make easy work of this by cutting the entire plants off at ground level, then pick off the best leaves. You can dry basil leaves, but freezing it or using it in vinegar best preserves the herb’s flavor. You can also use it to flavor oils and pesto, which should be kept refrigerated or frozen. (Don’t keep fresh leaves in the refrigerator, though, as they will turn brown.)
You can also keep cut stems fresh for a few days by putting the cut ends in water just like a cut flower. They will add a fresh basil fragrance to the air.
For the fullest flavor, add fresh basil to dishes within the last 5 or 10 minutes of cooking time. Use fresh basil in tomato dishes, soups, salads, sauces, and pasta. Its flavor blends well with parsley, rosemary, oregano, thyme, and sage.
When I pick basil leaves, do I pluck them from the top or the bottom of the stem?
Basil, like many herbs, is grown for its foliage, not fruit or flowers. Anything you can do to encourage new leaves, such as fertilizing or pruning, is a good idea. Picking leaves is also pruning, so you can stimulate your plant to grow while harvesting. Always cut leaves from the top of the plant. Instead of cutting individual leaves, pinch out the top of the stem. This should include the small new leaves or a flower stalk and a pair of full-size leaves growing below the tip. You can also cut low enough to include several pairs of leaves if you need a lot of basil. Just be sure that your cut is on a light-colored stem that is relatively young. The older woody portions may not sprout new growth.
What can I do to save my basil from frost?
If the frost is early and light, cover plants with a sheet or blanket. The best way is to put stakes in the ground around the plant so that the leaves are not touching the covering. Weight the edge of the covering with stones or bricks. Uncover as soon as temperatures rise above 40 degrees. Cutting branches of basil and putting them in a vase of water is always a good idea, as they will last up to a week. If you want to preserve basil for use during the winter, puree leaves in a food processor with olive oil. Freeze the puree in ice cube trays, and then store the cubes in freezer bags. These make individual portions to be added to soups, spaghetti sauce, or any recipe calling for fresh basil.
Can I transplant my basil into a pot to bring indoors this winter?
Basil is difficult to grow indoors, but if you have a sunny window, you can give it a try. Growth will not be as robust, nor will the flavor be as good, but it is definitely better than having no fresh basil at all. In fall you may not have any choice but to transplant large plants from the garden, but it is better to start fresh with a small plant if possible. If the basil in your garden has reseeded, dig up a big seedling to transplant. If you must dig the big plant in the garden, get as much of the roots as possible and put it in a pot large enough for the growing plant, using a good quality potting mix. This will be like transplanting a garden shrub.
How do I care for an indoor pot of basil?
Expect the plant to wilt and drop leaves as it makes the transition to the indoors. Watch for signs of mealy bugs and spider mites, two common problems with indoor herbs. Because you want to eat the leaves, most pesticides are not an option. Try misting plants daily to increase humidity and decrease the likelihood of spider mites. Then if problems appear, treat with insecticidal soap or diluted dishwashing liquid.
My basil has bare stems at the top and a few ugly leaves below. What happened?
Beginning in midsummer, basil plants will bloom, make seeds, and die. That is the normal lifecycle for an annual plant like basil. Just like zinnias, marigolds, and other annuals benefit from deadheading (removing spent flowers), so will basil. Unlike showy annuals flowers, basil blooms are subtle, looking like a small bud or green cone at the top of the stem. With time, this bud will expand into several inches of insignificant white flowers. Go ahead and pinch off the flower bud as soon as it appears. Continue pinching through the latter part of summer to prevent seed set and to encourage new leafy growth.
My basil turns my fingers black. What can I do?
When harvesting basil, you will find that any bruises will turn black, including the plant juice that gets on your fingers and under your nail when pinching the stem. Use kitchen scissors to avoid the problem. If you are cutting a lot of basil, as you would at the end of the season or when you want to make pesto, wear gloves. If you already have stained fingers, use a pumice soap and/or stone on your fingers, and do the best you can with a nail brush. Otherwise, the color will wear off in a few days.