Why Are My Tomato Plant Leaves Curling | How To Fix It

Shop-bought tomatoes can not compare to homegrown fruit, picked fresh from the plant. With countless varieties of all different shapes and sizes, tomato plants are the perfect addition to any growing space.

Tomatoes (Solanum lycopersicum) do have very specific growing requirements however, and they tend to display their displeasure in a number of different ways if their needs are not met. Noticing your tomato plant leaves curling is a clear indication that they are not happy, and it’s down to the grower to interpret why it’s happening and how to resolve this. 

If this is a problem you’re experiencing then read on! I’ve put together the best advice to help you understand what causes leaf curl on tomato plants and how to fix it.

Why Do Tomato Leaves Curl?

Tomato plants provide an abundance of fruit when kept content. However, plants will cease to produce fruit and can decline quickly if symptoms such as curling leaves are not remedied.

There are a number of different reasons why tomato leaves curl. This reaction can be a result of a bacterial disease, pest attacks, exposure to high temperatures, dehydration, or fertilizer burn – all of which will have to be identified, addressed, and ultimately rectified to be sure you have fixed the problem.

Care must be taken when identifying the cause of tomato leaves curling as plants can display similar symptoms for many different afflictions.

What Causes Tomato Leaves To Curl?

Seeing plants in distress can be alarming, but in most instances, if you act quickly, the catalyst for the leaf curl can be fixed easily without lasting damage.

It can sometimes be difficult to determine what causes tomato leaves to curl due to plants displaying very similar symptoms in different situations. With this in mind, here are the top 8 common causes of tomato leaf curl and how to fix them:

1. Transplant Shock

Tomato plants are very sensitive so when it’s time to move them to their final growing positions (especially when planted outside) they can have a tendency to show their displeasure which can cause their leaves to curl. 

To avoid transplant shock from occurring it’s a good idea to harden off your plants. Do this by introducing young plants to their more exposed growing environment gradually by placing them outside for increased periods of time throughout the day.

Transplant shock is usually only temporary and should resolve itself in a few weeks as the plant becomes more used to its new growing conditions.

2. Disease or Viral Infection

Disease and viruses are common amongst tomato plants and some will cause leaves to curl as soon as the infection takes hold. As the plant succumbs to the contamination, its health will deteriorate further with discolored black foliage, stunted growth, and little or no fruit production. 

One common cause is a virus known as tomato chlorosis. This virus can cause leaves to become yellow, brittle, and rolled. The virus is transmitted by whitefly and although an irritation to tomato plants, it will cause minor loss if caught early and affected leaves are removed.

In addition to being transferred by pests, other causes of plant viruses and diseases come from dirty tools or via wind transmission, and once infected there is no organic or chemical solution. 

Infected leaves/foliage need to be removed to reduce the spread. Growing disease-resistant varieties can limit leaf curl and infection in the future.

Unfortunately, the initial symptoms of infections and infestations can appear much like herbicide/chemical damage. The difference between herbicide damage and a virus tends to become more apparent over time as tomato plants tend to deteriorate quickly when disease or viral infection occurs.

3. Excessive Pruning

Pruning tomato plants is essential especially when growing indeterminate or ‘single stem’ varieties. However, too much pruning can shock the plant causing leaves to curl or discolor, stunted growth, and decreased fruit production.

To avoid causing the leaves to curl – prune little and often rather than in large batches or all at once.

4. Irregular Watering

A lack of moisture in the soil causes leaves to curl as they try to reserve water, therefore, a regular and consistent watering routine is crucial for healthy and fruitful plants, especially for those of us who garden in hotter climate zones. 

Dry soil is even more common when tomatoes are either grown in pots and containers (as they dry out quickly) or when grown in the ground during periods of drought. 

To avoid leaf curl as a result of dry soil, keep the soil moist but not soggy. Water early morning to allow plants to absorb sufficient moisture before temperatures rise throughout the day.    

5. Excessive Heat

Tomatoes are heat-loving plants and will thrive in full sun. However, if plants are subjected to consistent heat of  90°F or more with no respite they will show signs of fatigue. Signs of this stress will be displayed by curling leaves.

Regular watering and providing shade during the hottest part of the day will resolve this without causing any lasting damage.

6. Too Much Fertilizer

Tomato plants are heavy feeders and will need a regular feeding routine to encourage lots of juicy, tasty fruit.

However, excessive amounts of fertilizer, especially those containing high nitrogen, can cause stress which may cause leaves to curl.

If you suspect too much fertilizer is to blame for curling leaves on your tomato plant, I recommend reducing the frequency of feeds or diluting the strength. For potted plants, and where there is evidence of salt build-up in the soil, flush the soil with water and repeat if necessary. 

In addition, avoid fertilizers containing nitrogen when plants are fruiting.

7. Chemical Exposure

Although an uncommon reason for tomato leaves curling chemical exposure must always be a consideration especially when gardening near farms or near other fruit and vegetable growers.

Leaf curl can occur when plants are subjected to chemical drift which has been carried by the wind.  

Tomato leaves can curl upwards or downwards as a result of this damage with new leaf growth showing initial signs of abnormality.

If plants have not been exposed to extreme amounts of herbicides they can recover, however, if leaves continue to curl combined with malformed fruits I recommend disposing of the plant entirely. 

8. Excessive Wind

Although not an issue for all gardeners – excessive wind can be a contributory factor in plants displaying curling leaves. Whilst this problem does not have serious repercussions on tomato plants, it can delay fruit production if excessive winds persist or the problem is not resolved.

Use taller companion plants to act as protection, set up a wind-break, or move/grow tomato plants in a more sheltered position where possible.

/grow tomato plant

FAQ – Tomato Plant Leaves Curling

Can tomatoes recover from leaf curl?

Most of the environmental factors that cause leaf curl are easy to remedy by amending your care routine. Problems such as over-pruning or damage caused by viruses will depend on how much of the plant has been affected. As a rule during most growth stages of the plant, as long as there are growing points remaining, the plant can recover.

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.