Spring cold snaps can do damage to some plants, but it depends on just how cold it gets and what type of plants are growing in your garden.
Plants that come out of the ground on their own are generally fine. The exception to this is if you get a hard freeze after your local areas normal date of last frost in the spring. A very late frost or freeze can damage the young leaves of some ornamental trees. Some varieties of Japanese maples are especially susceptible to late frosts. If hosta leaves are partially open these can also exhibit frost damage. The plants may not look as nice as you would like all summer, but the cold won’t actually kill any of them.
Apple and peach blooms can be damaged by a freeze if readings go below 28F for many hours. At those levels the blooms of pansies can also be damaged, but the plants themselves will still live.
Houseplants should not be put outside until all danger of frost has passed. Most of your houseplants are not hardy enough to handle any temperature under freezing and many can be damaged by temperatures even under 40F.
If you’re a vegetable gardener there are two categories of vegetables when it comes to the cold. There are those plants like kale, collards, lettuce, beets, broccoli, and cauliflower which thrive in cold weather and those like tomatoes, peppers, okra and corn which die in cold weather. Most garden centers won’t sell the warm weather plants before it’s time to put them in the ground. However, if you get a late frost or freeze you might need to cover the second group of plants.
Fava beans and peas grow well in the cool air, while string beans won’t germinate until the soil is warm and will quickly rot in the ground in cold or very wet conditions.
Newspaper, sheets and even burlap make good covers for frost protection. Tarps are not good as the plastic won’t breathe and can actually do damage to the plants. The best material to use for frost protection is something called woven row cover. This lightweight material is available from many different suppliers. I get mine from Johnny’s Selected Seeds in Maine, but you can find it elsewhere too. There are different weights of row cover depending on your need. Some is made specifically for frost and freeze protection because it’s heavier. This variety of row cover lets in less sunlight so it’s not good for insect protection. For that, use a lighter weight row cover.
If it’s windy during a cold snap be sure to secure your method of protection. I have covered my plants at 7PM in the evening thinking they would be fine only to wake-up in the morning to dead plants because the covers blew off.
Most of the time a late cold snap only lasts one or two nights and are usually followed by a period of more typical spring-warmth.
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