Growing Basil - July 8, 2009
Jeff Schalau, Associate Agent, Agriculture & Natural Resources
University of Arizona Cooperative Extension, Yavapai County
Herbs are fun to grow because they are relatively fast growing and many of them have a degree of insect resistance due to the essential oils they contain. One of the easiest and most prolific herbs to grow is sweet basil (Ocimum basilicum). You haven’t lived until you’ve made fresh pesto from basil grown in your garden.
Basil is a member of the mint family (Lamiaceae) which helps explain its intense fragrances. Some references say it is native to southern Asia and islands of the south Pacific. Others cite its home as Iran and even Africa. This confusion may come about because it has been used as a culinary and medicinal herb throughout history. Basil eventually made its way to Italy, France, and the New World. Today, it is grown commercially in California, but I would recommend growing your own or buying it fresh from a local market grower.
This tender annual is primarily grown for its flavorful leaves, used fresh or dried, to liven up numerous dishes of both Asian and Western cuisines. Most would agree that dried basil does not compare in flavor with fresh basil. Culinary basil varieties have smooth, succulent leaves that are very soft and almost waxy. Other varieties, grown for aromatic qualities, can have somewhat fuzzy leaves.
Basil grows best in a sunny location that receives at least 6 to 8 hours of direct sun per day. It requires well-drained soil and is somewhat tolerant of alkaline soils (up to 7.5). As with any annual crop, basil performs best when the soil is amended with some compost. The easiest method is to sow seeds directly in soil after the danger of frost has passed (as with green beans, squash, and cucumbers) and rake lightly to cover seed with about 1/4 inch of soil. Seeds should germinate within 5 to 7 days. Newly germinated basil seedlings have two broad, D-shaped seed leaves (cotyledons). Alternately, basil can be sown 1/2 inch apart in flats, kept warm and moist, then transplanted after they have at least two sets of true leaves. Thin or transplant young plants to have a final spacing of 6 to 12 inches apart.
Until summer rains begin, water deeply every 4-7 days to insure the roots are receiving adequate moisture. Container-grown plants will dry out faster than those in garden beds. Pots should have a drainage hole and soil media should be a well-drained potting mix. Fertilize sparingly – where compost was used to amend soil, additional fertilization may not be necessary. If plants are not vigorous and older leaves are yellowing, they may be nitrogen deficient. If fertilizer is applied, use a balanced fertilizer (roughly equal percentages of N-P-K) at about half the recommended rate for vegetables. Organic gardeners can use fish emulsion, bat guano, alfalfa meal, blood meal, etc. Organic forms will not be as readily available to plants because they must be consumed by soil microbes before plant available nutrients are released.
Begin harvesting basil after plants have reached at least 6 to 8 inches in height. Single fresh leaves can be snipped and used as needed. If whole stems are harvested, cut just above a pair of leaves. New growth will emerge from the leaf axils below the cut within a week. For culinary basil, it is important to prune the plant regularly during the growing season to maintain productivity and promote succulent new growth. Watch for flowers to form and simply pinch them off the plant. Basil that is allowed to flower and form seed will stop growing and become somewhat bitter.
Sweet (or Italian) basil is used in pesto and compliments the flavor of tomatoes. I enjoy growing Thai sweet basil which has an anise-like aroma (I love it in summer garden omelets). Lettuce-leaf basil has large, crinkled leaves, a mild flavor and is excellent in salads. There are many other species and cultivars of basil: purple-leafed, lemon, cinnamon, etc. Whichever basil you grow, taste the fresh leaves and use your imagination to create flavored vinegars, salads, and main dishes.
The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/.
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Last Updated: June 30, 2009
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