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.
Temperatures below 60°F at night will also result in blossom drop. At temperatures below 40°F, peppers may show some chilling injury. A shortage of water at bloom time can also result in blossom drop or failure to set fruit.
40F won't hurt any of those plants but if the soil gets too cold they can all be affected. So if it's me I cover if I think the soil might get too cold too long. Most warm season crops I like to maintain 60F soil temp minimum.
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.
Cucumbers are heat-sensitive and do best in temperatures between 60-90°F (16-32°C). They can tolerate some heat but will become stressed if temperatures exceed 95°F (35°C). Cucumbers can also be damaged by frost and temperatures below 50°F (10°C).
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.
H2 Rating - 34 to 41° F (1 to 5 C)
Overall, these annuals are the most delicate of all the hardy annuals - one might call them half-hardy since they are really only hardy into the few temperatures just above freezing. And it's important to NOT let them freeze.
Conversely, shivering peppers aren't happy peppers. 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.
Zucchini is a warm-season crop that cannot tolerate frost or freezing temperatures, so its best to plant your zucchini in the early summer, when temperatures are at least 70 degrees Fahrenheit or more.
If you're trying to squeeze a few more days/weeks out of your pepper harvest and the temperatures are dropping at or below 40˚ F, we recommend covering your peppers with frost cloth or a small hoop house with greenhouse film to keep them warm during the cold nights if you can to help them keep producing.
Cover Plants
Once temperatures drop below about 28°F, covering is typically no longer effective at preventing cold damage. Occasionally even with covering you may still see damage at temperatures above 28°F, especially when the below freezing temperatures are prolonged (5 hours or more).
If you're looking for tips for protecting your plants from frost, avoid using garbage bags as plant covers. Trash bags are not the best protection against frost damage, primarily due to their material. Most garbage bags are made out of low-density polyethylene plastic.
❄️ Frost Protection
Use Frost Covers: Employ row covers or frost blankets on cold nights to trap heat. Remove them once the frost has passed to prevent overheating. Prune Strategically: Prune your pepper plants to a few main branches to reduce the risk of pest infestation and to promote vigorous growth in spring.
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.
Tomato plants can suffer from chilling injuries when temperatures are between 0 °C to 5 °C . Pepper plants can also suffer from chilling injury if temperatures stay between 0 to 10 °C (32 to 50 °F ) for a long time. This injury may appear as puckered leaves and stunted growth.
Jalapeño peppers are sensitive to cold and can be severely damaged or killed by frost. Understanding their temperature thresholds is crucial for winter care. Optimal growing temperatures range from 70-85°F (21-29°C). Temperatures below 40°F (4°C) can cause stress, and frost is often lethal.
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. To find the threshold for your plants, search garden books and online resources.
Basil is an extreme example of this, as the leaves can turn black when the temperatures dip into the 40s. Other plants are a little more tolerant, and warm temperatures following a short cold exposure can reverse some of the injury.
Even prolonged exposure to temperatures below 55 degrees F. (13 C.) can cause decay, pitting, and water-soaked areas on fruit. Sudden cold snaps can cause cucumber plant damage on leaves, stems, and fruit or even kill the plants.
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.
How Cold Can Tomatoes Tolerate? Tomato seeds won't germinate when the soil temperature is below 50 degrees Fahrenheit. Tomato seedlings suffer cold damage in temperatures below 60 degrees Fahrenheit. Some tomato varieties are bred to be more cold-tolerant and can set fruit when it's below 55 degrees Fahrenheit.
Peppers are not likely to continue to ripen off the vine, but there are a few things you can do to mimic the process. Leave the bell pepper on the countertop or on a window sill at room temperature to encourage the pepper to continue ripening. Placing a bell pepper in the fridge will stop the ripening process.
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.
While your tomato fruit plants can survive in non-freezing conditions, temperatures below 55°F can still cause damage to your tomato plants.
Many newer cultivars are able to withstand hotter temperatures, but no petunias thrive in chilly temperatures. When spring temperatures dip below 40 degrees F, either cover your outdoor petunias with frost cloth or bring them indoors. Temperatures below freezing will kill them in a jiffy.