You’ve been growing some seedlings in your garden that suddenly have their leaves curling. You wonder why this is happening even when you take care of them.

Your seedling leaves are curling because you’re not giving them enough water. Some other problems that could cause curling are overwatering, pests, diseases, lack of nutrients, too much heat, or windy conditions.

I’ve written all the details below that will help you figure out what is wrong with your seedlings and how you can help them bounce back.

Underwatering or overwatering

The most common reason that your seedling leaves are curling is due to a lack of water. You may be growing plants that need a lot of water. Or you may be growing plants in pots that dry out faster.

It could also be that the temperature has increased a lot during summer causing the water to evaporate faster from the soil. If the seedlings don’t get the required amount of water they will start to curl up.

The other side of the problem is overwatering. This happens when you keep adding water to the soil till the roots are soaking in it.

The common issue of root rot occurs which means the roots are not able to function and send the required nutrients and moisture to the plant. The side effect of this problem is that the seedling leaves will curl down.

The solution to both of these problems is to understand when your plant needs water and how much you should provide.

You should read up about the plant you are growing and find out its needs. Some plants will need less water while others will need lots of it.

Once you know the needs of your plant, you can check the moisture in the soil. It’s best to do this every day when you check up on your plants.

Stick your finger 1-2 inches into the soil and check if the soil sticks to it. If the finger comes out dry, it means you need to water the soil.

Water the soil well with a watering can until the water goes deep into the soil. If you’re growing the seedlings in a pot, water the potting soil till the water runs out from the drainage holes at the bottom.

Too much heat

The seedlings you’re growing may need full sun or partial sun. Plants that need full sun need at least 6-8 hours of direct sunlight.

If the temperature in your garden rises above what the seedling can bear, it will try to protect the leaves. They start curling up so the surface area is reduced, and they can retain moisture.

The good thing is that this is a temporary issue. The moment the temperature returns to normal, the seedling leaves will also uncurl.

You can shade the seedling from the harsh sun by using a cover. If you’re growing the seedling in a container, you can move it to a shaded location in your garden.

Wind

If you live in a windy area, you’ll find that the seedling leaves are curling up. This is the same reason as too much heat affecting the leaves. They try to protect themselves and the moisture by curling and reducing the surface area.

Once the windy conditions have died down, the seedling leaves will return to their normal form.

You can use a windshield to protect your seedlings from harsh wind. Or you can grow them near a large tree, plant, wall, or fence. Just make sure the plant can still get the required amount of sunlight so it grows well.

Severe pruning

Your seedlings are young and trying to grow foliage so they can produce their food. If they lose their leaves for some reason, they will get stressed. And the remaining leaves will curl down.

This could happen because you’ve heard that pruning foliage will encourage the plant to grow even more.

But such pruning should only be done once the plant has matured. And you should not prune more than 1/3rd of the plant at one time.

Transplant shock

You may have started seeds indoors that have grown into seedlings. Or you may have bought them from a nursery or garden center.

Now it’s time to move those seedlings to your outdoor garden. But if you transplant them before they adapt to the outdoor conditions, they suffer transplant shock.

The seedlings are not able to cope with the intense sunlight, heat, wind, or rain that may be hitting your outdoor garden. The plant will get stressed and the leaves will curl down due to such stress.

You need to help the seedlings adapt to the conditions before moving them out. The simplest way to do this is to keep the seedlings outdoors for a couple of hours every day.

You can keep increasing the time a little every day on how long you keep the seedlings out. Make sure to keep them away from direct sunlight and wind when you begin.

After a week, the seedlings will have adapted to the outdoor conditions and you can now move them out to your garden.

If the seedlings are already in transplant shock, it’s best to move them back to a comfortable area indoors or a shaded location of your garden. Once they recover, you can help them get used to the conditions before moving them back to your garden.

Lack of nutrients

Some plants you grow will be heavy feeders which means you need to give them a good supply of nutrients. If the nutrients are lacking, the seedling leaves will curl down.

I suggest you mix in a good amount of compost when preparing the soil in the garden. This will give a good start of nutrients to your garden. And it will introduce beneficial organisms in the soil that will keep creating more.

If the compost is not sufficient for your hungry plants, you’ll need to add some fertilizer. I recommend using organic fertilizer that is gentle on your plants as well as the wildlife.

Follow the instructions by the manufacturer on how much and how often you need to use the fertilizer. This is especially important if you use chemical fertilizer. Too much will burn the roots and reduce the nutrients reaching the plant. And cause the leaves to droop.

Pests

It’s natural that pests may attack your plants at some point. If the infestation is low, you can just let them be. But if there are many pests, they will damage the plant and cause a lack of nutrients and growth.

Pests like aphids and whiteflies suck the sap out of the leaves causing a drop in their capacity to produce food. And the leaves will start curling down as a result.

Some other pests like snails, slugs, caterpillars will chew up the leaves and stress the plant growth.

I recommend checking on the seedlings in your garden every day in the morning when you water them. You will notice any pests immediately and can take the necessary action to get rid of them.

The best choice for many pest problems is to pick them by hand and drop them in a bucket of soapy water. Pests like aphids and whiteflies can be dropped to the soil with a spray of water.

Pests like snails, slugs, and caterpillars can be picked by hand. Or some such pests can be attracted by a beer trap and drown in them.

Diseases

Diseases are another common problem that will affect your garden at some time. Some of these diseases will be cosmetic but others can damage or kill your plants.

If your seedlings are infected by a disease that affects the foliage, there is a good chance the leaves will start curling down.

Diseases can be fungal, bacterial, or viral when it comes to their source. Fungal diseases include powdery mildew, root rot, and Fusarium rot. Viral diseases include leaf curl virus and tomato mosaic virus. Bacterial diseases include leaf spot and blight.

Fungal diseases attack plants when there is a moist environment created. I would suggest you only water the base of the plant and not splash water on the foliage. This creates a moist condition to attract fungal diseases.

You should also keep a good distance between plants so there is good air circulation among the foliage. It’s also good to prune some foliage to keep this good airflow.

If the plant has been affected by a fungal disease, you can trim the affected part to help the plant recover. If the damage is all over the seedling, you won’t have a choice but to dispose of the plant.

Bacterial and viral diseases can reach your plant from the soil, water, birds, and insects. There’s not much you can do to protect your seedlings from them. 

But you should prevent your seedlings from coming under stress that can weaken their immune system. If possible, try to grow a variety of the plant that would be resistant to some of these diseases.

Once your seedling has been infected by a bacterial or viral disease that is damaging the foliage, you’ll just have to expect that the plant will die at some stage.