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.
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.
Starting in mid to late September, it is beneficial to watch the forecast and take note of forecasted low overnight temperatures. Once temperatures dip to the mid-30s °F, it will be necessary to take action by bringing plants indoors, covering plants, or utilizing cold frames and hoop tunnels.
When low temperatures 36°F to 32°F are in your forecast, cover your tender plants. Because low-lying areas within a landscape can experience slightly lower temperatures, you may want to cover your plants when the temperature dips below 40°F to be safe.
When temperatures dip below 50-55, I bring my plants in. This is my preference, but most houseplants will tolerate temps down to 40-ish. I'd say anywhere between 45-55 degrees is a good time to bring them in. This is when most pests and bugs have either died off or gone south for the winter.
There are, of course, many variables that can affect winter hardiness in a plant, but in general, my rule of thumb is as long as the mercury stays in the 20's at night and rises above freezing during the day, our plants should be just fine.
Another temperature to keep in mind: tomato plants will not survive in temperatures below 35 degrees Fahrenheit, and will not thrive at temperatures below 50 degrees.
There is no universal temperature for all plants that is too cold, so that is why it is important to do your research. However, it is safe to say if living in an environment with harsh winters and temperatures below 20°F, it is always wise to bring plants indoors during this time, if possible.
Each plant has a different threshold when it comes to dealing with the cold. Some plants can survive outside even when temperatures hit freezing. Others need to be brought indoors when temperatures reach the mid-40s.
A "killing frost" is now considered to be a temperature of 28°F in the United States, but in 1916, the type of frost was determined by the level of damage incurred.
First, it's good to know which plants are sensitive to temps around 35 or 40 degrees F. These are common tender plants that will need some protection. Hanging baskets: begonias, calibrachoa, gerbera, impatiens, vinca, euphorbia, and scoparia.
So when temperatures start dipping below 50º F, leave the tomatoes on the vine if warmer days and nights are forecast. But if temperatures have started on a steady downward slide, go ahead and pick the mature green tomatoes and bring them indoors.
Although frost will not cause as much damage as a hard freeze, you should prepare certain plants ahead of cold weather. Despite its convenience, there's one item you should stay away from to cover your plants. If you're looking for tips for protecting your plants from frost, avoid using garbage bags as plant covers.
Covering plant material at temperatures between 39-30 with freeze cloth or covering can be effective. Prolonged exposure at temperatures of 28 degrees and below will notice protection results diminish with each degree dropped.
So will peppers survive 40 degrees? To sum it up, most peppers won't necessarily DIE from 40˚ F temperatures, but their growth can be stunted, and they may be slow to recover so it's best to keep them warm if possible.
When do I know it's safe to bring my plant outside? It's safe to move your plants outside when the outdoor temperatures stay consistently above 50°F. Pay attention to the weather report. If nighttime temperatures are set to fall below 50°F, bring your plants in for the night.
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.
Many indoor plants will see damage when temperatures drop to the mid to lower 40s°F and nearly all will die if exposed to below freezing temperatures. Watch the weather forecast and bring plants back indoors well before nighttime temperatures get too cold. Before bringing them inside, check for insects.
Will a covered porch protect plants from frost? Yes, it will provide partial protection from light ice and chilly winds. Uproot tender perennials — Tender perennials are plants that cannot withstand deep freeze (roots, bulbs, tubers, and corms).
Wind, humidity, and each plant's cold-tolerating genetics play a role in addition to temperature. That's why it's possible to go out on a morning when the temperature didn't go below, say, 35 degrees and see frost on the impatiens. Frost can form on plants even when temperatures are above the 32-degree freeze point.
If the temperatures are below freezing all winter, it is unlikely you will need to water your plants. In freezing temperatures your plants would not be able to benefit from watering because the ground would be frozen and any water would just run off or freeze rather than being absorbed by the plant's roots.
As gardeners, we base our frost dates on 32 degrees Fahrenheit (0 degrees Celsius) to avoid the risk of any plant death. However, even if air temperatures are as high as 38°F, frosts may occur on the ground and plants. It's better to protect plants just in case!
It's sunny again… wait… ), but some vegetables won't be happy (and grow into incredibly prolific tomato producers - yes, I'm talking to you, tomato fanatics) if you don't protect them until night temperatures warm up consistently to 50 degrees and above.
Daytime temperatures below 65°F can lead to fruit set failure—the pepper equivalent of stage fright. At night, anything under 50°F is an invitation to leaf curl and overall plant stress. It's like the plants are pulling their leaves up to their chins, trying to keep warm.