Tomato leaves curling is a warning sign that you should not ignore.
To produce the loads of delicious tomatoes you anticipate, it takes a healthy plant with lush foliage.
But your harvest could be at risk when you see leaves curling on your tomato plants.
Credit: GoodLifeStudio / Getty Images
Curled-up leaves indicate that something is not right in the environment or within the plant itself.
We also tell you the best course of action for each problem.
Dr. Ajay NairisaProfessor and the Chair of the Department of Horticulture at Iowa State University.
Tough Growing Conditions
Nature can throw a variety of challenges attomato plants as they grow.
Less-than-ideal growing conditions are the most common cause of tomato leaves curling and the easiest to remedy.
In overly hot and dry conditions, the leaf margins roll upwards.
Nair says that you’ll usually see curling more on the lower leaves.
The science behind this stress-induced leaf curl reveals that it’s a way that plants actively protect themselves.
This internal water deficit causes leaflets to curl up.
A curled leaf absorbs less of the sun’s energy and loses less water.
Leaf curl is a self-defense mechanism.
Start with good watering practices.
Aim to provide tomato plants with1 inch of water a week.
Avoid overhead watering to prevent the spread of disease.
Add a 2-inchlayer of mulcharound tomato plants to limit soil moisture evaporation.
Tomato leaves curling brought on by harsh growing conditions usually resolves when the conditions improve.
Don’t worry about long-term effects.
A short battle with leaf curl “does not significantly reduce plant growth or yield,” says Nair.
Let new leaves grow freely.
The plant should return to good health in a couple of weeks.
Transplant Shock
Moving seedlings or young starts into your garden stresses tomato plants.
Some tomato varieties curl their leaves in response to temperature fluctuations and root disturbance associated with transplanting.
After leaf curl caused bytransplant shock, plants often recover on their own within a couple of weeks.
Provide plenty of water as your tomatoes settle in.
To minimize transplant shock in the future, double-check toharden off seedlingsbefore planting and gently handle the root ball.
Weed Killers
A weed-free lawn nearby could be the reason for tomato leaves curling.
“Off-target drift of herbicides such as 2,4-D or dicamba is a frequent offender,” says Nair.
This looks different than the tightly curled or rolled leaves sparked by hot, dry growing conditions.
Another source of herbicide-related leaf curl is contaminated compost or mulch.
If you spread this compost in your garden, it may impact your tomatoes (and other plants).
There is no cure for herbicide-induced leaf curl.
Take a “wait and see” approach.
Some plants will overcome the effects and produce a crop.
Other plants will die without fruiting.
In the future, avoid using weed killers near tomato plants.
Know thesource of your compostand mulch, making sure to purchase from a reputable dealer.
Tomato Diseases
Though not very common, someviral tomato diseasescould be why you’re seeing curling leaves.
Individual new leaflets often curl due to diseases.
There is no cure for tomato viruses.
In the future, choose newer varieties that offer disease resistance to viruses.
