Understanding the temperature tolerances of the vegetables you grow is crucial for their growth and productivity. By providing the optimal temperature conditions, you can ensure healthy plants and a bountiful harvest. The veggies listed in this post are the same ones listed in our Planting Calendar Climate Zone 5b.
It's important to note that temperature tolerances may vary slightly depending on the variety of the vegetable, as well as other environmental factors such as humidity and soil moisture. When growing vegetables, it's always best to consult the seed packet or a gardening guide to determine the optimal temperature range for the specific variety of vegetable.
Learn how to protect your plants from both excessive heat and cold in our Season Extension blog post.
Brassica family temperature tolerances
Broccolini is a hybrid vegetable, a cross between broccoli and Chinese kale. It is known for its mild and slightly sweet taste, tender stems, and delicate florets. Broccolini can tolerate both high and low temperatures, but it grows best in cool weather with temperatures between 50-70°F (10-21°C). If the temperature gets too hot, broccolini can bolt (start to flower prematurely) and become bitter. On the other hand, if the temperature drops below 25°F (-4°C), broccolini can suffer from frost damage.
Brussels sprouts are a type of cabbage that grow in small, compact heads on a tall stem. They have a slightly bitter taste and are often roasted or sautéed. Brussels sprouts are also quite hardy and can tolerate both high and low temperatures. They grow best in cool weather with temperatures between 45-75°F (7-24°C). However, they can withstand temperatures as low as 20°F (-7°C) without suffering significant damage. High temperatures can cause the sprouts to open up and become loose, which can reduce their quality and flavor.
Cabbage is a cruciferous vegetable that comes in a variety of shapes and colors, including green, purple, and white. It has a slightly sweet taste and is often used in salads, coleslaw, and stir-fries. Cabbage is a cool-season crop and grows best in temperatures between 60-65°F (15-18°C). However, it can tolerate temperatures as low as 20°F (-7°C) and as high as 80°F (27°C) for short periods of time. If the temperature gets too hot, cabbage can bolt and become bitter. If the temperature drops below 20°F (-7°C), cabbage can suffer from frost damage.
Cauliflower is a member of the cruciferous family and is closely related to broccoli and cabbage. It has a mild, nutty flavor and is often used in soups, stews, and roasted vegetable dishes. Cauliflower prefers cool weather and grows best in temperatures between 60-68°F (15-20°C). If the temperature gets too high, cauliflower can become tough and bitter. If the temperature drops below 25°F (-4°C), cauliflower can suffer from frost damage.
Collards are a leafy green vegetable that is often used in Southern cooking. They have a slightly bitter taste and are rich in nutrients such as vitamin K and vitamin C. Collards are a cool-season crop and grow best in temperatures between 60-65°F (15-18°C). However, they can tolerate temperatures as low as 20°F (-7°C) and as high as 90°F (32°C) for short periods of time. If the temperature gets too high, collards can bolt and become tough and bitter. If the temperature drops below 20°F (-7°C), collards can suffer from frost damage.
Kale is a leafy green vegetable that is often used in salads, smoothies, and soups. It has a slightly bitter taste and is known for its high nutrient content, including vitamin K, vitamin C, and iron. Kale prefers cool weather and grows best in temperatures between 60-70°F (15-21°C). However, it can tolerate temperatures as low as 20°F (-7°C) and as high as 80°F (27°C) for short periods of time. If the temperature gets too high, kale can become tough and bitter. If the temperature drops below 20°F (-7°C), kale can suffer from frost damage.
Kohlrabi can tolerate a wide range of temperatures, but it grows best in cool weather conditions. It's important to prevent heat stress, by providing adequate irrigation and shade. It can withstand light frosts but not extended periods of cold weather. The ideal temperature range for kohlrabi growth and development is between 60°F to 75°F (15°C to 24°C). Kohlrabi can tolerate high temperatures up to 85°F (29°C), but prolonged exposure to such temperatures can cause bolting, or premature flowering, which negatively affects the quality of the kohlrabi bulb. Cooler temperatures can result in sweeter and crisper kohlrabi bulbs. Prolonged exposure to freezing temperatures can damage or kill the plant, causing the bulb to become soft and spongy.
Cucurbit family temperature tolerances
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).
Cantaloupes prefer warm temperatures and grow best in temperatures between 70-85°F (21-29°C). They can tolerate some heat but may become stressed if temperatures exceed 90°F (32°C). Cantaloupes can also be damaged by frost and temperatures below 50°F (10°C).
Summer squash, such as zucchini and yellow squash, thrive in warm temperatures between 70-95°F (21-35°C). They can tolerate some heat but may become stressed if temperatures exceed 100°F (38°C). Summer squash can also be damaged by frost and temperatures below 50°F (10°C).
Winter squash, such as butternut and acorn squash, can tolerate cooler temperatures than summer squash. They grow best in temperatures between 60-75°F (16-24°C) and can tolerate temperatures as low as 50°F (10°C). Winter squash can be damaged by frost and temperatures below
Zucchini, like other summer squash, prefer warm temperatures between 70-95°F (21-35°C). They can tolerate some heat but may become stressed if temperatures exceed 100°F (38°C). Zucchini can also be damaged by frost and temperatures below 50°F (10°C).
Watermelons are heat-loving plants that do best in temperatures between 70-85°F (21-29°C). They can tolerate some heat but may become stressed if temperatures exceed 90°F (32°C). Watermelons can also be damaged by frost and temperatures below 50°F (10°C).
Fruiting crop temperature tolerances
In general temperatures between 40 and 50º for a night won’t hurt most tomato varieties and peppers. The severe cold damage comes below 40º. It’s best to transplant seedlings at the warmer part of the planting period. A “heat wave” with temperatures above 85ª and 90º F can severely damage tomato plants. Some varieties can stop producing fruit for 2 weeks, and other varieties stop producing fruit for the rest of the growing season.
Cherry tomatoes are warm-season plants and prefer temperatures between 70°F to 80°F (21°C to 27°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 50°F (10°C). If temperatures exceed 95°F (35°C), cherry tomato plants may drop their flowers and fruits.
Roma tomatoes are also warm-season plants and prefer temperatures between 70°F to 85°F (21°C to 29°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 55°F (13°C). Like cherry tomatoes, Roma tomatoes may drop their flowers and fruits if temperatures exceed 95°F (35°C).
Heirloom tomatoes are also warm-season plants and prefer temperatures between 70°F to 85°F (21°C to 29°C). They can tolerate slightly cooler temperatures but don't grow well in temperatures below 55°F (13°C). If temperatures exceed 95°F (35°C), heirloom tomato plants may drop their flowers and fruits.
Eggplant is a warm-season vegetable that thrives in temperatures between 70°F to 85°F (21°C to 29°C). They prefer warm nights, and the optimal temperature range for eggplant growth is 75°F to 85°F (24°C to 29°C). Eggplants can tolerate slightly higher temperatures, but extended periods of temperatures over 90°F (32°C) can stress the plant and cause damage.
Sweet peppers are also warm-season vegetables and prefer temperatures between 70°F to 85°F (21°C to 29°C). They can tolerate slightly cooler temperatures but prefer warm days and nights. The optimal temperature range for sweet pepper growth is 75°F to 85°F (24°C to 29°C). Temperatures above 90°F (32°C) can cause the plant to stop growing and may lead to flower and fruit drop.
Hot peppers are similar to sweet peppers in their temperature requirements, preferring warm temperatures between 70°F to 85°F (21°C to 29°C). However, some hot pepper varieties, such as habaneros, can tolerate higher temperatures up to 95°F (35°C). Like sweet peppers, hot peppers may stop growing and drop flowers and fruit at temperatures above 90°F (32°C).
Greens temperature tolerances
Amaranth is tolerant of high temperatures and can grow well in warm climates. It can tolerate temperatures up to 95°F (35°C) but prefers a range between 70-85°F (21-29°C). In contrast, amaranth cannot tolerate frost or temperatures below 50°F (10°C).
Swiss chard is a cool-season vegetable that prefers mild temperatures. It can tolerate temperatures down to 15°F (-9°C) but prefers a temperature range of 50-75°F (10-24°C). High temperatures can cause Swiss chard to bolt, or flower and produce seeds prematurely.
Lettuce is a cool-season vegetable that prefers temperatures between 60-65°F (16-18°C). It can tolerate temperatures down to 20°F (-7°C) but will bolt in high temperatures above 75°F (24°C).
New Zealand spinach is a heat-loving plant that can tolerate temperatures up to 95°F (35°C). It prefers temperatures between 70-85°F (21-29°C) and can tolerate light frosts down to 32°F (0°C).
Spinach is a cool-season vegetable that prefers temperatures between 50-65°F (10-18°C). It can tolerate temperatures down to 20°F (-7°C) but will bolt in high temperatures above 75°F (24°C).
Bok choy is a cool-season vegetable that prefers temperatures between 60-65°F (16-18°C). It can tolerate temperatures down to 20°F (-7°C) but will bolt in high temperatures above 75°F (24°C).
Herb temperature tolerances
Basil is a heat-loving herb that can tolerate high temperatures up to 90°F (32°C). However, prolonged exposure to temperatures above 90°F can cause the leaves to wilt and dry out. Basil is sensitive to cold temperatures and can be damaged by frost. It can tolerate temperatures as low as 50°F (10°C), but anything below that can cause damage or death to the plant.
Cilantro prefers cooler temperatures and can start to bolt (go to seed) when temperatures reach above 75°F (24°C). It can tolerate higher temperatures up to 85°F (29°C) with proper care and watering. Cilantro can tolerate some frost, but prolonged exposure to temperatures below 32°F (0°C) can cause damage or death to the plant.
Dill can tolerate temperatures up to 85°F (29°C), but prefers cooler temperatures. High temperatures can cause the plant to bolt and go to seed prematurely. Dill can tolerate light frost and temperatures as low as 25°F (-4°C). However, prolonged exposure to freezing temperatures can cause damage or death to the plant.
Oregano is a heat-loving herb that can tolerate high temperatures up to 100°F (38°C). It prefers temperatures between 70°F to 80°F (21°C to 27°C) for optimal growth. Oregano is fairly cold hardy and can tolerate temperatures as low as 20°F (-7°C) with some protection. Extended exposure to freezing temperatures can cause damage or death to the plant.
Sage is a heat-loving herb that can tolerate high temperatures up to 90°F (32°C). However, it prefers temperatures between 60°F to 70°F (16°C to 21°C) for optimal growth. Sage is fairly cold hardy and can tolerate temperatures as low as 10°F (-12°C) with some protection. However, extended exposure to freezing temperatures can cause damage or death to the plant.
Parsley prefers cooler temperatures and can start to wilt and dry out when temperatures reach above 85°F (29°C). It is best grown in temperatures between 50°F to 70°F (10°C to 21°C). Parsley is somewhat cold hardy and can tolerate light frost and temperatures as low as 20°F (-7°C). However, extended exposure to freezing temperatures can cause damage or death to the plant.
Lavender: English lavender is winter-hardy to Zone 5 and may only need a bit of help in the form of a thin layer of straw. Otherwise, lavender shouldn't need any extra care outdoors. Spanish and French lavenders, on the other hand, are only hardy to Zone 8, and will need to be brought indoors in colder areas. Before the first frost, it is best to bring the potted lavender plants indoors and place them in a dry, unheated room. Cellars, garages, greenhouses or winter gardens are particularly suitable for overwintering.
Legume temperature tolerances
While these legumes can tolerate a range of temperatures, they each have an optimal temperature range for growth and yield. It is important to consider these temperature ranges when planting and caring for legumes in your garden to ensure the best results.
Bush beans can tolerate temperatures ranging from 60°F to 85°F (15°C to 29°C). However, they prefer a temperature range of 70°F to 80°F (21°C to 27°C) for optimal growth. Temperatures below 60°F (15°C) can slow down the growth of bush beans, while temperatures above 85°F (29°C) can cause the flowers to drop, resulting in reduced yield.
Pole beans can tolerate temperatures ranging from 50°F to 86°F (10°C to 30°C). However, they prefer a temperature range of 60°F to 70°F (15°C to 21°C) for optimal growth. Temperatures below 50°F (10°C) can cause poor germination, and temperatures above 86°F (30°C) can cause flowers to drop, resulting in reduced yield.
Fava beans can tolerate temperatures ranging from 40°F to 75°F (4°C to 24°C). They prefer a temperature range of 60°F to 65°F (15°C to 18°C) for optimal growth. Temperatures above 75°F (24°C) can cause the plants to bolt, resulting in reduced yield.
Snap peas can tolerate temperatures ranging from 45°F to 75°F (7°C to 24°C). They prefer a temperature range of 60°F to 70°F (15°C to 21°C) for optimal growth. Temperatures above 75°F (24°C) can cause the plants to become stressed, resulting in reduced yield.
Snow peas can tolerate temperatures ranging from 50°F to 75°F (10°C to 24°C). They prefer a temperature range of 60°F to 65°F (15°C to 18°C) for optimal growth. Temperatures above 75°F (24°C) can cause the pods to become tough and inedible.
Shell peas can tolerate temperatures ranging from 45°F to 75°F (7°C to 24°C). They prefer a temperature range of 60°F to 70°F (15°C to 21°C) for optimal growth. Temperatures above 75°F (24°C) can cause the pods to mature too quickly, resulting in reduced yield.
Root Crop temperature tolerances
These root vegetables have different temperature preferences and tolerances, but they are generally hardy and can withstand a range of temperatures. However, extreme temperatures can cause damage or poor growth, so it's best to plant them in their preferred temperature range and provide protection in case of temperature extremes.
Beets are a hardy root vegetable that can tolerate both high and low temperatures. They can grow in temperatures ranging from 50°F (10°C) to 85°F (29°C). However, they prefer cooler temperatures between 60°F (15°C) and 65°F (18°C). Beets can withstand light frosts but may suffer from frost damage if temperatures drop below 28°F (-2°C) for an extended period.
Carrots are another hardy root vegetable that can tolerate a wide range of temperatures. They prefer cooler temperatures between 60°F (15°C) and 70°F (21°C) but can grow in temperatures ranging from 40°F (4°C) to 80°F (27°C). However, they may suffer from poor growth and deformities in hot temperatures above 80°F (27°C). In cold temperatures, they can tolerate light frosts but may suffer damage if temperatures drop below 20°F (-7°C) for an extended period.
Garlic planting times are unique. Plant the cloves at the optimum time for your climate zone. In zones 0 to 4 plant in late August to September. In zones 5 to 8 plant in mid-October through mid-November. In zones 9 to 10 plant in late November to December or before the ground freezes. Garlic is a cool-season crop that prefers temperatures between 60°F (15°C) and 70°F (21°C). It can tolerate temperatures ranging from 50°F (10°C) to 90°F (32°C) but may suffer from poor growth and bulb development in temperatures above 90°F (32°C). Garlic can also withstand light frosts, but temperatures below 20°F (-7°C) can cause severe damage.
Green onions, also known as scallions, are a cool-season crop that prefers temperatures between 60°F (15°C) and 70°F (21°C). They can tolerate temperatures ranging from 45°F (7°C) to 85°F (29°C) but may suffer from poor growth in temperatures above 85°F (29°C). Green onions can also withstand light frosts, but temperatures below 20°F (-7°C) can cause severe damage.
Parsnips are a cool-season crop that prefers temperatures between 50°F (10°C) and 65°F (18°C). They can tolerate temperatures ranging from 40°F (4°C) to 75°F (24°C) but may suffer from poor growth in temperatures above 75°F (24°C). Parsnips can withstand light frosts but may suffer damage if temperatures drop below 20°F (-7°C) for an extended period.
Radishes are a cool-season crop that prefers temperatures between 50°F (10°C) and 65°F (18°C). They can tolerate temperatures ranging from 40°F (4°C) to 85°F (29°C) but may suffer from poor growth in temperatures above 85°F (29°C). Radishes can withstand light frosts, but temperatures below 20°F (-7°C) can cause severe damage.
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