Q. As someone who is new to herbs, I would like to start growing basil in my garden with little to no basil casualties. Do you have any growing basil tips for me?
A. Select a warm, well-lit site. If you’re an experienced vegetable gardener, but new to herbs, plant your basil along with your other vegetables. Basil and tomatoes planted together are said to provide each other with insect protection and vigor, according to folk wisdom.
Loosen the soil by spading at least eight inches deep. Unless you have already grown vegetables or flowers there successfully, a soil test is a good idea; local soil conditions are so variable and their treatment so specific that blanket statements can be misleading. Your county’s Cooperative Extension agent can arrange for a soil test and advise you on the additives that will work in your soil.
You can start basil from seed in the house at any time, but wait until air temperatures and the ground are warm before sowing outside. Sow the seed 1/4-inch-deep in prepared potting mix (inside) or soil (outside). Firm the planting medium over the seeds and water gently. Seedlings will be up in three to five days if the temperature is warm. Indoors, keep the seedlings in good light (fluorescent tubes are fine, especially if sunlight is limited); transplant to larger pots when roots fill their original container.
After the danger of frost is past—about the time you’d plant tomatoes—you can harden off your indoor basil plants (accustom them to outside conditions by leaving the pots outside for increasingly longer periods), and transplant them to your prepared basil bed. If you buy basil plants at a garden center, don’t neglect the hardening-off step. Greenhouse-grown plants are likely to have been plenty pampered.
After hardening off, it’s time to settle your basil plants in the prepared soil of your basil bed. Gently loosen the root ball, place it in a planting hole three times the size of the root ball (a little deeper than the plants were in the pot), and water well. Gently fill the holes and press lightly to avoid leaving air pockets. Now, prune the tops, leaving a few sets of leaves on the remaining stem, and eat them! In a few weeks, you will be able to harvest again. You can start harvesting basil from the plants you started indoors when there are three or four pairs of true leaves above the first, or seed, leaves. Leave at least one pair of true leaves on the stalk to stimulate the plant to produce two new stalks at that point. With care and regular cutting, the garden harvest continues until frost.
In heavy loam and clay soils, provide at least an inch of water per week. For lighter loam and sandy soils, water twice a week, one inch each time. Mulching will help keep water in the root zone, where it is needed. In July or August, after the basil has been harvested several times, I like to give the plants a shot of fish emulsion, compost, composted manure or chemical fertilizer formulated for tomatoes.
Q. What basil pests should I look out for when tending my basil?
A. In the garden, basil has few pests. Generally, I don’t intercede with occasional or spotty insect problems unless they threaten the crop. I let the natural predators do their job. However, if you do find a pest that’s harming your basil, it may be one of these little guys.
Caterpillars: Pick them off or use the bacterium Bacillus thuringiensis (sold as Dipel, among others) as a safe control.
Slugs and snails: Put down sharp sand as an abrasive barrier, or use a slug bait. You may need to remove mulch from around your plants to make the area less attractive to these animals.
Cutworms: These may be a problem during the first two weeks after transplanting basil to the garden. Protect the stems of your transplants with cardboard collars (easily made from frozen juice cans with the ends removed). Or sprinkle a four-inch circle of wood ashes around each plant, being careful not to contact the stem. You may use lime instead of ashes in acid soil.
Grasshoppers and big beetles: Unless you’re experiencing a veritable plague, ignore them.
Whitefly, spittlebugs and aphids: Wash plants daily with a water spray. For heavy infestations, spray with a mild soap and garlic solution. If your basil plant is indoors, you need to take action immediately to gain control of these insects. Cut off affected parts or leaves that have eggs on them and get rid of them.
Learn More Growing Basil Tips
Marilyn Hampstead is the author of The Basil Book (Pocket Books, 1984).