Master Gardener Sue Morris: Blame hot weather for vegetable garden production
Temperatures have not been optimal for vegetable production this season. Blooms fall off before becoming fruit, and once it gets over 90, many bees slow down and pollinate less as well.
Have you been doing everything right but think you should be getting better production from your vegetable garden? Rest assured it isn’t your fault as the University of Minnesota says we can blame it on the hot weather.
Be careful not to give too much nitrogen to your plants in this heat. You will get lush green plants but no harvestable vegetables.
Hot day and nighttime temperatures cause flowers to drop. Flowers will form but then die and fall off the plant before becoming fruit. This can happen at temperatures ranging from 75 to 95 degrees.
The University has had reports that this is noticeable in tomatoes. They tell us that tomatoes produce new flowers often and these flowers have a 50-hour-long window in which to be pollinated. With high temps, the plant becomes stressed and burns through its energy stores.
Cucumbers develop odd and uneven shapes when not fully pollinated. Bees prefer temperatures ranging between 60 and 90 degrees. Once it gets over 90, many bees slow down and pollinate less. This can lead to deformed cucumbers, summer squash and melons.
Guess it's just not us humans that don’t enjoy working in the hot weather. Poor pollination can also result in fruit that forms and then quickly dies.
It is said that hot temperatures can change how many male and female flowers are present. So even if you see lots of flowering, these could be male flowers and they will not produce fruit.
Keep reading below the related content for more of this week's column from Master Gardener Sue Morris.
We should be enjoying ripe tomatoes now that night temperatures are cooling some. Tomato ripening happens in two stages.
In the first stage of ripening, the tomato becomes mature and is green, seeds form and the area around them becomes soft and gelatinous.
In the second stage, the tomato turns red and experts tell us that the optimum temperature range for that is between 68 and 77 degrees.
We can’t fool Mother Nature, so we need to be patient. Make notes on how your varieties are performing and consider trying a new heat-tolerant variety in the future. After the last two years, it appears we are in for some hot dry summers.
One thing about dry weather is that we aren't bothered by mosquitoes. What hot and dry weather does bring are the grasshoppers. We had a large grasshopper population going into this year because of the hot and dry 2021. The population continues to grow.
Lots of grasshoppers have been spotted on community gardens this year, but they haven’t been feeding on crops. They prefer feeding on pollinator plantings or weedy areas at the edge of the garden.
Grasshoppers are often not worth treating. This is because the damage they do often isn’t significant. Plants can tolerate feeding, so it isn’t worth treating over a few holey leaves.
Grasshoppers are also large and highly mobile, making it hard to use pesticides on them.
Attempts to treat grasshoppers in gardens are often unsuccessful, and the pesticides can have unintended effects on pollinators and other good bugs.
The reason we don’t have large grasshopper populations during rainy years is that the wet weather promotes the development and spread of a grasshopper killing fungus. This fungus infects grasshoppers, hijacking their bodies.
This information was obtained from an article by Marissa Schuh, Extension educator in horticulture integrated pest management.
Master Gardener Sue Morris has been writing this column since 1991 for Kandiyohi County newspapers. Morris has been certified through the University of Minnesota as a gardening and horticulture expert since 1983. She lives in Kandiyohi County.