Common Environmental Problems

Basil is very sensitive to cool temperatures. These plants are growing in a greenhouse, where both soil and air temperatures are closely monitored.


The plant on the left may be suffering from a nutrient deficiency. One of the symptoms of iron deficiency is "interveinal chlorosis" of new leaves -- in other words, the leaf veins remain green, but the tissue between the veins turns yellow. The plant on the right appears healthy.

Before you resort to using pesticides, first rule out the possibility that environmental factors are causing the symptoms you see on your plants. Here are some common plant problems and the environmental conditions that may cause them.

• Bleached or white areas on the leaves of new transplants can indicate sunburn. Be sure to harden off transplants by gradually exposing them to outdoor conditions over the course of a week or two.



• Wilting can indicate insect and disease problems, but first check the moisture of the soil. Don't assume the plants have enough water; dig into the soil and make sure it is moist down to a depth of at least 8 to 10 inches for mature flower and vegetable plants. Water established plants deeply once every week or two, rather than sprinkling them daily. You want them to develop a deep root system that is resistant to drought. Note, however, that even some healthy plants will wilt slightly during very sunny, hot, and/or windy days, but will recover at dusk. Basil plants, which are very sensitive to cool temperatures, may wilt if exposed to temperatures in the 40s.
Plants may also wilt if their roots have been damaged from sitting in saturated soil, so take care not to overwater.


• Blackening of leaves can indicate frost damage. If the upper, exposed leaves are damaged, but interior foliage is fine, then a light frost may have nipped the plants.



• Heavy winds, torrential rain, and hail will tear plant leaves.



• Nutrient deficiencies can cause various symptoms, from weakened growth to yellowing leaves.

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