Growing Basil

Wait until soil is thoroughly warm before placing mulch around basil plants.

Start this tender annual indoors four to six weeks before you intend to set the plants out. Herb nurseryman Tom DeBaggio of Arlington, Virginia, recommends waiting until night temperatures are above 55°F and not mulching until the soil is thoroughly warmed up.

Basil likes a fertile soil, though it tolerates a wide range of pH (4.5 to 6.5). Although some folks insist that the flavor is better if basil isn't fertilized, grows and looks better if it's fed at planting time, and again during the season, perhaps after a heavy picking. Supplemental irrigation can double yields, Simon reports.

Like most herbs, basil has few pests. Japanese beetles can easily be kept off with spunbonded polyester row covers. If slugs are a problem on new transplants, try using a barrier of copper flashing.

A devestating disease, fusarium wilt of basil, reached North America via infected seed in the 1990s. Symptoms include sudden wilting and leaf drop, accompanied by dark streaks on the stems, usually in weather above 80°F. If you notice the symptoms, quickly dig up the infected plant, along with all soil around the roots, and discard it. If part of your garden becomes infected, avoid spreading the disease by moving soil around on your tools or tiller, and consider growing your basil in containers. You can also try your luck with a fusarium-resistant variety, such as 'Nufar'.

Basil is also susceptible to a few bacterial rots that show up on stems or leaf clusters, usually in cool, wet weather, in winter greenhouse production, or late in the season. Planting in well-drained soil, spacing plants so they dry out after they're watered, and practicing good garden sanitation are the keys to control.

Harvest and Storage

Tip growth, harvested just before the plant flowers, is the most flavorful.

The optimum time to harvest basil is just before it flowers. Many fresh-market growers here in North Carolina like to pick just the tip clusters; stemless and succulent, these are preferred by restaurant buyers. But if you continually pick this way, your plants may start flowering almost simultaneously with new leaf formation. Basil is programmed to initiate flowering when it has six pairs of leaves on a stalk," says Tom DeBaggio, "so I like to cut it back to two leaves per stem. Don't let it get past four pairs. You can harvest the entire plant about every three weeks, and at the end of the season there will be 12 to 24 lateral branches."

In my own garden, I tend to follow a combination method: pinching off the top clusters for sale or home use, and then when the flowers are starting to get ahead of me, cutting the plants way back for a pesto- or vinegar-making session. I repeat this progression several times during the season.

Studies done at Michigan State University by horticulturist Diana Dostol have shown that basil actually keeps longest if it is picked as late in the day as possible. Dostol also worked on post-harvest storage. "If you simply put basil in a perforated plastic bag at room temperature," she says, "it will keep for 10 to 14 days." The optimum storage temperature is 60°F. "At refrigerator temperature, which is about 41°F," says Dostol, "basil only keeps two to three days."

I like to keep a few stems in a jar of water on the kitchen counter. They last a long time, they are right there when I need a few leaves, and they may conveniently root some plants for winter. "If you store basil stems in water," advises Dostol, "treat them like cut flowers, changing the water frequently. You can also add something like lemon juice to the water to bring down the pH and retard bacterial growth."

Basil's bountiful production can be both a delight and challenge. In my family, when the lettuce is all gone, basil's not just an herb, it becomes our main leafy green. A midsummer salad consists of tomatoes, peppers, cucumbers and a huge handful of basil. Every year, I put bags or yogurt cups of pesto in the freezer and chip off chunks as needed for the ultimate winter convenience meal. I also make basil vinegar and dry the leaves for cool-weather cooking. Then basil's evocative summertime smell fills my house, and I can practically feel the sun on my back, hear the leaves rustling and taste the ripe tomatoes warm in the garden.

By Deborah Wechsler is a garden writer based in Pittsboro, North Carolina.