Several reasons cause limp tomato leaves. Tomato plants thrive in daily average temperatures of 23.9 degrees C. The quality of the fruit diminishes above 32.2 degrees C. Wilting leaves indicate something's amiss Lack of water, overpruning, insect infestations, excessive heat and harmful herbicides are the most common reasons for limp leaves. A brisk frost also causes leaves to wilt, as the rays of the sun warm the plant and decomposition begins.
Lack of Water and Overwatering
Tomato plants need water during the initial growing, flowering and fruiting stages. Drier climates may require up to 2 inches/ 5 cm of water per week. The surest way to limp leaves is underwatering a tomato plant. Overwatering can be just a detrimental Too much water causes roots to rot and diminishes the plant's ability to deliver water to the cell structures in the stems and leaves. One inch of water per week is the norm for tomato plants.
Pruning a tomato plant allows the plant to produce larger tomatoes. This pruning, if taken too far, causes stress and shock to the leaves. Leaf curling or wilting is common, but not life threatening. Prune but don't overdo it.
Check the leaves for holes and torn-looking edges. Grasshoppers and tomato hornworms feed on the leaves. Pick these insects off or turn some chickens out into the tomato patch for a 20 minutes a day. If you don't have chickens, a nontoxic, apply a tomato-friendly biological insecticide.
Sunburn or sunscald happens with too many hot sunny days in a row. Set up shade netting.
Always mark your herbicide spray container so you don't accidentally use it to spray insecticide. Herbicides can drift on the wind for more than 1/2 mile. Use caution if you have to spray weeds on the lawn near your garden.
A frost destroys the cell structure and leaves will begin drooping as soon as the sun thaws them out. Check frost forecasts so you can harvest your tomatoes before a hard frost hits. Never eat frost-damaged tomatoes.
Verticillium and Fusarium Wilts
If the leaves turn yellow, wilt and drop off, you're plant may have a soil-borne disease. Plant Verticillium and Fusarium resistant varieties next year.