Why Are My Tomato Leaves Curling?


Upward curling tomato leaves indicate stress more often than disease.

“My tomato plants have leaves curling upwards along the edges. Why?” Questions from Andy of Zionsville, Indiana

Answer: Based on your photo, your leaf curl appears to be caused by something in the environment rather than a disease. There is a Tomato Yellow Leaf Curl Virus, but your plant does not appear to have several of the symptoms, such as stunting, yellowing, and leaf browning. Tomato plants, like yours, more commonly experience physiological leaf curl when subjected to various environmental stresses. Here are four possible sources of stress able to cause leaf curl.

Environmental Tomato Leaf Curl Causes

  1. Water stress (too little or too much water) — Vines fail to grow as well when water is lacking, and they develop root rot when there is too much water. Either problem can cause leaf curl. Provode plants with regular, even watering for best growth.
  2. Heat stress — Temperatures over 85 degrees F can cause some tomato plants stress, resulting in leaf curl. Some tomatoes are more heat-tolerant. Two good heat-tolerant varieties are the large, red-fruited ‘Heatmaster‘, which can take the high heat of the South, and disease and heat-resistant ‘Heatwave II‘, which bears deep red tomatoes with good flavor.
  3. Wind stress — High winds can cause rapid water loss from the leaves. Leaf curl can result.
  4. Herbicide damage – Glyphosate herbicide damage is most common and can cause leaf curl if a small amount reaches your tomatoes from a upwind application.

Could any possibilities be the cause? Please let me know. In the interim, click here to read more about leaf curl, and watch the video below about growing flawless tomatoes!

Happy gardening!

Jessie Keith

Grower’s Gold Horticulturist