Backyard Gardener: Hard freeze marks end of growing season

Hello Mid-Ohio Valley Farmers and Gardeners. Most likely we will say goodbye to the growing season this week in the Valley. A hard freeze is in the forecast so any late squash, tomatoes or other vegetables need to be harvested quickly. Tender herbs such as basil should be gathered up as well.

Do not be discouraged by the coming frost. First, many cold hardy vegetables such as swiss chard, kale, collards and other greens actually become sweeter after the frost. Kale and swiss chard can survive temperature into the lower 20s (degrees F). Second, my grandparents said two weeks of good weather (warm and dry for farmers to harvest crops) always followed the first hard freeze.

A killing frost can result from canopy temperatures dropping 2-5 degrees below freezing for 5-10 minutes, or from a sustained temperature 31. 5-32 F lasting 3-5 hours. Most of our summertime heat loving vegetables such as tomatoes, peppers, sweet corn and beans will be killed by the hard frost or freeze.

Your best bet is to harvest warm season sensitive crops quickly before a hard freeze, especially tomatoes. A hard freeze will cause tissue damage and fruit will deteriorate rapidly.

Tomatoes can be ripened indoors. Look over your plants and pick any tomatoes that appear to be partially ripe or light green. Fruit that is dark green will not ripen indoors; it hasn’t matured enough. Check for disease or dead stems, ensure the plants are still healthy, to ensure a safe product.

Tomatoes being ripened should be stored at temperatures between 55 to 70 degrees Fahrenheit in well-ventilated areas out of sunlight. Green tomatoes should ripen in about two weeks, while more mature fruit will ripen in a few days to a week in ideal conditions.

Root crops such as carrots, turnips, beets and parsnips of course are below the surface of the soil and are not affected by frosts. However, they can be affected by freezing. Root crops can remain in the garden after a frost and still be removed in good condition later but get them dug and stored before the ground freezes hard.

Keep in mind sweet potatoes are a little different. After a killing frost, immediately get those sweet potatoes dug and into storage. They will quickly begin to rot from diseases entering the plant through the dead top.

Be careful digging. They don’t have a protective hard layer as do the tubers of Irish potatoes. Cuts and bruises on sweet potato roots are not good, as they often lead to rotting in storage.

Irish or cobbler potatoes can tolerate light frost, but when the first hard frost is expected, it’s time to get out the forks (I mean potato forks) and start digging. Same story with scrapes and bruises with Irish potatoes. They will cause rot during storage. Damaged potatoes should be used as soon as possible.

After harvesting, all potatoes must be cured. Let them sit in temperatures of 45 to 60 degrees Fahrenheit for about two weeks. This will give the skins time to harden and minor injuries to seal.

Floating row covers, low tunnels and other protective covers can be used by home gardeners as a low-cost way to protect sensitive vegetables from frost. Floating row covers are lightweight synthetic fabrics laid directly on top of a row of plants to protect against cold and insects. Low tunnels are fabric or plastic covers supported above the crop using wire hoops, metal pipe or bent PVC hoops.

Material edges for both are commonly weighted with sand bags or simply buried with soil to prevent loss due to wind. Lightweight covers come in varying sizes and weights, providing different levels of frost protection.

Greenhouse film (plastic) provides significant frost protection while still allowing substantial light transmission. However, the primary drawback is that this material is not self-venting. Gardeners must remove the cover on sunny days to prevent overheating. Contact me with questions at the WVU Extension Office at 304 424-1960 or at jj. barrett@mail. wvu. edu. Good Luck and Happy Gardening.


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