The Challenges of Growing Basil
Basil is promoted as a plant that thrives in hot weather. Hot weather is a relative term, however, and “hot” in Texas may not be the same as “hot” in another region. Research shows that the optimum temperature range for growing basil is between 70° and 90°F. Basil can tolerate temperatures to 95°F and above but, like most plants, it can still suffer the effects of heat stress: slowed growth, decreased leaf size and the development of off flavors. Prolonged hot weather may encourage early flowering which in turn triggers the plant to stop leaf production.
To get the most production during high temperatures, it is critical to irrigate regularly. Basil does not tolerate drought stress. This herb requires well drained soil that is kept evenly moist. Drip irrigation is preferred since it minimizes damage to foliage caused by moisture contact with the leaves. Use mulch to conserve moisture. Although basil is considered a full sun annual, requiring six to eight hours of sun
per day, it may benefit from protection from the late afternoon sun during the peak of summer.
Another approach to improving your plant’s appearance and increasing your basil yield is to pinch or prune the plant at regular intervals throughout the growing season. The practice of pinching involves some of the uppermost sets of leaves. Removing the growing point stimulates new branches to grow, resulting in a bushier plant that produces leaves over a longer period of time. If you desire maximum basil production, begin pinching plants early on, when plants are about 6 inches high and have three to five pairs of true leaves. You can continue pruning periodically, never removing more than 1/3 of the plant at a time.
If you are starting with transplants, allow them to get established in the garden before starting to cut. Pinching/pruning can be done with fingers or pruning shears. The following videos demonstrate the correct way to prune leaves to keep your plants healthy and productive:
