Once all danger of frost has passed, harden off your seedlings by placing them in a shady place outdoors and gradually exposing them to sunlight, starting with a bit of morning sun. Bring them in whenever temperatures fall under 45ºF. You can transplant them in the garden once nighttime temperatures stay above 55ºF.
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. Gardeners can use a frost date calendar to note their region's average dates of last frost in spring and first frost in fall.
You can preserve summer tomatoes by bringing 'outdoor' plants inside at the end of summer to save them over the winter. Older plants will gradually stop producing, so you can't save them forever, but it's possible to at least extend the harvest. However, you can also harvest indoor tomatoes throughout the year.
temps in the 40s are not going to harm your tomatos unless it is a constant temp in the lower 40s for days on end. If the temps dip into the mid 30's then you should cover them to shield them from the wind.
When the tomato plants are about 10 to 12 inches tall and the last chance of frost has passed in your growing zone, it's time to plant the tomato seedlings in the garden or patio container.
Most tomato seedlings are ready to move from the seed starting trays and into a larger container when they are three to four inches tall and have three or more sets of leaves. They should be transplanted into a larger container at least four weeks before planting outdoors so the root system has a chance to develop.
It is important to remember that tomatoes are warm weather plants and will not grow in temperatures below 50°F (10°C). The soil should also be warm enough – ideally 60°F (16°C). In general, 'if you're growing tomatoes from seeds you can sow indoors any time from March to the end of May.
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.
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.
Most houseplants are native to tropical areas and will not tolerate freezing temperatures. 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.
Remember that pots dry out quickly. Water potted tomato plants daily at the soil level. You'll know you've watered enough when the water trickles through the pot's drainage holes. A mature tomato plant in a pot uses a gallon of water daily but you may need to hydrate the plant twice a day in hot, dry conditions.
Too much bright direct sunlight on plants can raise temperatures too high for ripening and lead to cracking and sunscald. It can also create problems caused by high humidity or dry soil. Do tomatoes prefer morning or afternoon sun? Tomatoes need both morning and afternoon sun and at least six hours of sun a day.
Tomatoes are considered perennials, and as long as they're protected from the frost, they can continue to grow.
When to Bring Tomatoes Back Inside. Potted tomatoes that have been moved outdoors should be moved back inside before nighttime temperatures fall below 50 degrees Fahrenheit. Tomato plants crave warmth and do not react well to cold temperatures.
Cucumbers thrive best at relatively high temperatures, between 75 to 85 °F. The plants do not tolerate frost. Since they are a quick-growing crop, they must be well supplied with moisture and plant nutrients throughout the growing season.
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.
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.
Expect 5-10 large bell peppers per well-grown plant, and 20-50 hot peppers per plant. Storage: Peppers don't stay fresh and crunchy for more than a few days, even in the refrigerator, so use them while they are in season. Small chiles can be dried if laid on cookie sheets in an airy place.
Tomatoes will survive in temperatures above freezing (32 degrees F or 0 degrees C). They will only survive, however, and won't grow well or produce ripe fruit, in temperatures between freezing and 50 degrees F.
In the case of peppers, the ideal daytime temperature is 21-26°C (70-80°F). The ideal nighttime temperature is 18-21°C (65-70°F). Of course, these ranges may vary, depending on the pepper varieties you grow. Pepper plants may still grow outside of the ideal temperature range.
Frost Hardy
Root crops develop more sugars when the soil temperature is below 40 degrees Fahrenheit; and Brussels sprouts are often best after a light freeze. Among the hardiest vegetables are cole crops, which can tolerate moderate freezes (24 to 28 degrees Fahrenheit) : Broccoli, cauliflower (26 degrees Fahrenheit)
Try to plant tomatoes in a different spot every year, rotating through your garden space every three to four years. Planting them in the same place allows disease pathogens that are specific to tomatoes to build up in the soil. By moving them around in the garden each year, you can break up the disease cycle.
Do not leave your plants outside overnight until the night time temperatures are above 50 degrees. If you purchase tomato plants from a commercial grower, it's a good idea to ask if the plants have been hardened off.