Late summer can get really, scorching hot. And sometimes I have a few tomatoes that are right in direct sunlight long enough to cause the tomato skin to start “cooking” and die. It hasn’t been too bad of a problem as I’m usually able to get out to the garden and pick things before they start seriously rotting. The few sun scalded tomatoes I’ve had look like the side facing the sun got hit by a very hot hair dryer — starting to die, starting to brown.

While most garden plants need at least 6 hours of sunlight to be productive, too much sun combined with heat over 85-90°F can be damaging. Plants near light walls suffer from reflected sunlight and heat even when it’s not that hot out. And newly transplanted plants have delicate root hairs that make it hard for them to take up enough water. You might see major wilting or even plant death when temperatures spike.

Some symptoms of too much sun include:

• Tomatoes fail to pollinate so flowers fall off without making fruit
• Tomatoes and peppers get light brown, tough skin patches
• Sun scalded leaves with brown/white patches that eventually crumble
• Newly transplanted plants wilting or dying in high temps

Providing some shade during the most intense sunlight can help. Putting up shade cloths that block 30-40% of sunlight over plants gives them relief from the midday and afternoon heat. Make sure the structure holding up the shade cloth can withstand wind. It’s handy when it’s portable so you can move it around as needed. Position it so at least the west side of plants is shaded. In super hot areas, shade cloth over the top helps too.

Other tips:

• Water sufficiently
• Use organic mulch to keep soil cool and moist
• Fertilize appropriately for healthy foliage growth

What exactly causes sunscald on tomatoes? It happens when they get hit by direct sunlight without protection, like a sunburn. A few days of higher than normal temperatures usually isn’t a problem. But extended heat waves can lead to issues. You might notice white/brown spots on leaves and blotchy white/yellow/gray patches on fruit. Overpruning leaves the tomatoes exposed too.

It’s important to plant tomatoes at the right time for your climate so they fruit before extreme summer heat hits. In hot climates, choose heat-tolerant varieties with dense foliage. Reimer Seeds has a whole page of heat tolerant tomato varieties. Smaller cherry tomatoes also tend to get less sunscald than bigger beefsteak types that take longer to mature and have more surface area exposed.

You can take steps to prevent sunscald:

Use Shade Cloths: Block 30-75% of sunlight during the hottest parts of the day. An umbrella can work in a pinch!

Don’t Overprune: Pruning promotes fruit growth but leaves them vulnerable. Avoid overdoing it during summer heat waves. Even crispy sunburned leaves protect the fruit.

So what do you do if your tomato has a sunscalded white/yellow blemish? Cut around it and use the rest! But if it looks shriveled, blistered, or has deep cracks showing the inside, toss it.

A healthy plant can better fight off pests and diseases. Check for signs of stress like wilting, bleached foliage, blackened leaves, ragged foliage, off-color foliage, dried leaf margins, and burned patches.

If you see exposed fruits that are getting too much direct sun, try to reposition the leaves of the plant to help shade the fruits better.

Address environmental issues and you’ll have a happier garden!