Semi-hardy vegetables that can withstand light frost of air temperatures in the range of 28 to 32 degrees include beets, spring market carrots, parsnip, lettuce, chard, pea, Chinese cabbage, endive, radicchio, cauliflower, parsley and celery.
Colder temperatures (26-31 degrees F.) may burn foliage but will not kill broccoli, cabbage, cauliflower, chard, lettuce, mustard, onion, radish, and turnip. The real cold weather champs are beets, Brussels sprouts, carrots, collards, kale, parsley, and spinach.
Light freeze - 29° to 32° Fahrenheit will kill tender plants. Moderate freeze - 25° to 28° Fahrenheit is widely destructive to most vegetation. Severe or hard freeze - 25° Fahrenheit and colder causes heavy damage to most plants.
Seedlings, with their tender new leaves, often give up the ghost when temperatures dip to 32-33°F. Tropical plants have differing low-temperature thresholds. Some keel over when temps fall to 40°F; others crumble at 35°F. Other plants are just hardy by nature and can withstand temperatures as low as 18-20°F.
If it stays cold for more than one night, can I keep my plants covered, or should I remove the coverings at some point? A. Our recommendation would be to remove the cold protection covering once temperatures are above 32 degrees.
Second, know that a light frost—32°F and colder—kills all tender plants such as tomatoes. Hardier plants such as spinach and kale will survive until there's a hard freeze—28°F and colder. (We explain the frost tolerance level of different crops below.)
I did some research and found out that houseplants need to be taken indoors before overnight temperatures dip below 45 degrees. Most tropical plants suffer harm from temperatures below 40 degrees.
Once temperatures drop below 40°F, you may want to start covering your plants with a frost blanket depending on what you're growing, which we'll get into in just a bit. Freeze – A freeze is when the air temperature is 32°F or below.
Perennials. The newly emerged growth of most perennials can tolerate temperatures in the low 30s and upper 20s °F. This includes many early emerging perennials such as bleeding heart, daylily, catmint, and columbine. In most cases, early leaf growth on these plants will be just fine with cold temperatures.
If you're wondering at what temperature threshold you should be bringing your plants, there's a short answer: when nighttime temperatures reach 45 degrees (F), it's time to bring your plants indoors.
Like all living things, houseplants have specific temperature requirements. In order for them to survive and thrive, these must be met. Most plants prefer a temperature of no less than 60° F, though many can tolerate as low as 40° F.
Viola, winter jasmine, calendulas, and many plants love cooler temperatures, and they don't hesitate to take advantage of winter's pollinators. Plants like black-eyed Susans and lavender won't be making an appearance in winter. They prefer the warm weather of summer.
The easiest way to protect from a freeze is simply by covering plants with a sheet or a blanket. This acts like insulation, keeping warm air from the ground around the plant. The added warmth may be enough to keep a plant from freezing during a short cold snap.
Temperatures below 32 degrees can freeze the leaf tissue of cold-wimpy plants and turn them to mush after just a few hours. Some of the most tender annuals and veggies might not die but suffer cold-induced setbacks even when overnight lows dip below 40.
A covered porch usually provides protection from light frost, but the garage or sun room is better for freezing temperatures. A couple days in darkness won't hurt the plant. Or move them out during the day and back in at night, if cold temperatures persist.
Yes – if you secure the plant properly. Garbage bags work to cover plants and protect from frost, but they must not be allowed to touch the plant's surface. Use stakes and supports to create a tent-like structure over the plant, which will retain warm air. Make sure the trash bag goes all the way to the ground.
Use a frost blanket, cloche or row cover material – not plastic — to insulate the ground around your outdoor plants and keep them warm. Prop the cover with sticks or stakes to keep it from coming into direct contact with the new growth. And, make sure to remove the cover the next morning after the temperature warms up.
A technique that is sometimes successful is to move potted perennials indoors for the winter. This works best with tropical evergreen perennials, such as begonias, that keep growing through the winter. Small potted fruit trees that spend the summer on a deck or patio can also live indoors through winter.
Fiberglass, lead, iron, heavy plastic, and stone are the best weather-resistant containers to use; terra-cotta will eventually expand and crack with repeated freezing and thawing. Assemble your designs early enough that the plants have time to acclimate to their new pots before the hard freeze.