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Tips on Growing and Using Basil

When you plant basil depends on your region. In northern climates, basil plants can be set out when the danger of frost has passed, or it can be seeded outside at the same time you plant corn. In the South there are two seasons for this favorite herb. 

Basil is easy to grow.

Basil is easy to grow.

Rebecca Jordi, Director of Nassau County University of Florida Extension, explains, “Our sun is so intense, we can only grow it in late spring or early fall.” Southerners can usually set plants outside in late February or early March (sometimes needing a covering for cold protection). “When July hits we let it bolt, then at the end of August, plant it again,” she notes. 

Basils prefer rich, well-drained soil in full sun, although the intense afternoon sun can be hard on the plants in any region. Jordi says Florida’s plants thrive in dappled light in the hottest part of the day.  

Like most herbs, basils don’t need heavy feedings. In the garden, use a liquid fertilizer on the plants a couple of times a season, or every four to six weeks for plants grown in a container.  

To use basil, simply trim off the leaves to the next set (or two) down the stem. The more you pinch and prune, the more it grows. The greatest challenge with basil is to keep the plant trimmed frequently enough to prevent it from flowering, but with diligent pinching you should enjoy a long season of fresh leaves.  

If the plants do go to flower, try using those in dishes. “The flowers can be used as a garnish,” says White. “They are also really nice with fruit.”  

Do not store cut basil in the refrigerator, because it will promptly turn brown. Rinse the bunch gently in cool water, place it in a jar with water in it and set it on your counter to use as needed.

Notes on Basil Downy Mildew

Since it first appeared in the United States in 2007, downy mildew (Peronospora belbahrii) has caused commercial and home basil growers a lot of headaches in practically every state.  

It causes yellowing leaves that turn brown and die, so it may first seem to be a nutritional deficiency. When you look under the leaves, purple-gray spores are the dead giveaway that downy mildew is the culprit. In dry regions, though, these may not be obvious.  

“Put the leaves in a plastic bag and watch it,” recommends Margaret Tuttle McGrath, Associate Professor at the Long Island Horticultural Research & Extension Center of Cornell University. Within a day or two, if downy mildew is present the spores will become apparent.  

There is no remedy. McGrath says, “Affected leaves aren’t going to be useable. For the home gardener, pick them off.” You can’t eat the affected leaves, but the other ones are usable.  

Prevention is the key. When planting basil in the garden, provide plenty of space between the plants to allow ample air circulation.  

“We get dew overnight, so we’ll get into the 90 percent humidity range. That’s just perfect [to promote downy mildew growth]. As a home gardener, I grow the plants in pots and bring them in at night,” says McGrath. 

Read about cultivars that show resistance to downy mildew and fusarium wilt, another basil disease.