Question: My pepper and tomato plants are looking good and starting to set fruit. Last year, just before the peppers and tomatoes started to get ripe, the side facing the sun got scorched. How can I keep that from happening?
Answer: This is a common problem when we get these hot, dry days that stress the plants.
You can avoid this by planting the pepper and tomato plants close together and providing enough water and fertilizer to grow a robust foliage cover. Even then, the fruit that happens to form on the outer part of the plant and is exposed to the sun during the hottest part of the day is at risk.
My wife came up with the idea of providing a little protection by covering the plant with some sort of cover, like a bedsheet.
Floating row cover turns out to be the ideal material for this application. It is super light so it will not weigh down the plant and 87% of sunlight is transmitted through the cover. It defuses the sunlight in a way that not only eliminates the sun scorching problem but reduces the effect of shading so that more of the leaf surface gets enough light to support photosynthesis.
In addition, it seems to have some positive impact on the amount of blossom-end rot that occurs. More on that later.
Floating row cover is available online and at Young’s Nursery. You want the light-weight row cover (0.5 oz), not the heavier weight frost cover that looks about the same, but is heavier. You can simply cut a piece to the right size and drape it over the plant support system.
This will work to avoid the sun scorching but has some drawbacks. The wind might push the plant over, so additional support may be needed. If the plant becomes too enclosed by the row cover, predator bugs may not have enough access to keep sucking bugs like aphids under control. It also may hold too much humidity around the plant which can cause other issues.
I recommend creating a structure that supports the covering but also allows for free airflow around the plants.
I drive T-posts on both sides of the plant rows. Then I attach half-inch PVC pipes vertically to these posts with half-inch to three-quarter-inch tees to the top of the pipe. I slip the PVC pipe through the tees to provide a support that runs the length of both sides of the row about 7 feet above the ground. I then place the floating row cover over the pipes, stretching it over the plants and hanging down on either side. I attach the floating row cover to the pipe with PVC snap clips that are available online.
In the end, the row cover is suspended above the plants high enough to walk under so they can be attended to, unencumbered by the floating row cover and airflow is not impeded.
As a side benefit, this cover seems to help with blossom-end rot. This rot is caused by a lack of calcium being taken up by the plant. There are a lot of reasons this might happen — high among these reasons is inconsistent irrigation. Allowing a plant to become dehydrated and then reacting by over-watering is almost certain to result in rot.
So how does the floating row cover help? I do not have the science behind this but this is my working theory: during hot windy days, the plants become dehydrated and stressed. Then when the sun goes down in the Umpqua Valley, the temperatures drop into the 40s and the humidity goes up to 100% which has the effect of overwatering. The row cover moderates the dehydration and radiant heating from the sun during the day and reduces the radiant cooling during the night, both of which reduce the kinds of stress that trigger blossom-end rot.
The good news is this structure and floating row cover can be taken down and stored for use the following year. Expect to get a couple of years of use out of the row cover because the wind beats it up quite a bit. The rest of the structure will last for years.