In bright, hot weather, fruit exposed to the sun may develop a scalded, or sunburned, spot. This is most common on green fruit. At first a yellow patch appears on the part of the tomato that is in hot, direct sunlight; when the fruit ripens, it forms a gray spot with a papery surface.
Use shade cloth Shade helps tomatoes during hot weather--of course it does. Go stand in the sun on a 100 degree day then move over into the shade, you don't get sunburned and feels cooler in the shade, doesn't it? Your tomato will think just like you and won't get sunscald/sunburn.
To put it plain simple: plenty. Tomato plants need at least six hours of full sun exposure daily, but if you want to achieve the best results, increase the yield and grow sweeter fruits, you might aim to give your tomato plants at least eight hours of sun per day.
They much prefer 75 to 95. When temperatures get too hot during the day (over 85 degrees) or are too hot overnight (over 70 degrees) many vegetables including tomatoes and peppers will drop their blossoms. This will cause a noticeable drop off in harvest in a few weeks.
Leaf rolling and cupping
Corn and tomatoes are among many plants that commonly roll their leaves or cup in response to heat. Leaf surface area is minimized, and stomata (microscopic openings in leaves, like pores, that allow movement of moisture and gasses) close. Together, these reduce moisture loss in the plant.
Avoid Overwatering Tomatoes in Summer Weather
Tomato plants need an inch or two of water a week, and a deep soaking is better than a little water every day.
To protect fruit, try draping cheesecloth over the vines in mid to late summer, or train vines to a cage to shade developing fruit. Training the vines makes it easier to pick tomatoes, and it reduces fruit rot that can develop when tomatoes touch soil.
When the wait seems to go on forever and fruits stay green for weeks, it could be that they aren't getting enough sun. Tomato plants need full sun, or closer to eight hours consistently every day, through all growth stages. When your tomatoes refuse to turn red, they could be getting too little sun.
As temperatures increase, you might need to water tomato plants twice a day. Garden tomatoes typically require 1-2 inches of water a week. Tomato plants grown in containers need more water than garden tomatoes. Soil in containers heats up faster which leads to more water evaporation.
When suddenly set out in full blazing sun, the leaves can burn. Don't worry: the plant will recover. Isn't it interesting that leaves, like our winter skin, may react to that first sudden burst of sun? The bizarre shape of tomatoes like this may be brought on by cooler-than- normal weather.
Aim to prune plants when the suckers are between 2 and 4 inches long. Determinate tomato plants (those that reach 4 feet tall or so and stop growing) only need to be pruned once. Indeterminate tomatoes can be pruned every couple of weeks as they continue to produce new leaves.
Tomatoes need eight hours of daylight to flower. Sunlight gives your tomato plants the energy to produce fruit, so if your plant doesn't have enough sunlight, you're less likely to see tomatoes fruiting.
Plants will roll or cup leaves to reduce surface area and maintain the moisture in their leaves. Leaf rolling or cupping is a very common behavior in corn and tomato plants in response to heat stress.
The bark may show as an elongated canker (areas of dead bark) that appears sunken or discolored, followed by cracking and peeling of the bark. You'll find the damage on the south or southwest side of a tree. Wrapping your tree before winter on these thin barked trees may help prevent sunscald.
This works best with smaller tomatoes, as larger tomatoes need a minimum of 6 to 8 hours of sun daily. 3. If you can't find afternoon shade, create some by using shade cloth over your plants. Shade cloth comes in many thicknesses - be sure the cloth you're using doesn't block more than 50% of the sunlight.
Researchers have found that best yields occur with a shade structure that's open to the east (no cloth on that side), so the plants can be bathed in morning sun, but shielded from hot afternoon rays.
Tomatoes need plenty of sunlight to produce fruit, typically around six to eight hours a day. Too much sun and heat can cause tomatoes to get sunscald. “Sunscald happens when the tomatoes are hit with the direct waves of the sun without any protection, similar to sunburn on us humans,” says Key.
Fruiting plants like cucumbers need a good 6 to 8 hours of sunlight a day for best flower and fruit production. You can still grow cucumbers with less-than-ideal sun, but you'll find they take much longer to produce.
Tomatoes growing in pots have high water needs. The relatively small soil volume in the container limits the amount of water available to plants. During the heat of summer, container-grown tomatoes often need to be watered daily. Hot, windy conditions might require twice daily watering.
The condition causes pale white or yellowish blotches on the fruit where the sun's rays are most intense. It's more common on developing green fruit but sunscald can affect mature tomato fruit just as often.
Overwatering generally makes the plant look almost like it's rotting, as in drooping and turning soggy brown. My guess is it is having Nitrogen problems. Any type of vegetable fertilizer you buy at the store should work fine.
If your tomatoes wilt in the heat of the day even though you have watered them well in the morning, the cause is not lack of water. In high heat, plants can't take up water from their roots fast enough to make up for their loss through the leaves and they often wilt.
Plants in containers and hanging baskets may need water twice a day - especially when weather is windy and hot, containers dry out very quickly. Check often, as most will need water at least once a day, and some may need water in the morning and the evening.