What Is The Lowest Temperature Tomato Plants Can Tolerate? Ways To Protect Tomato Plants From Cold

Bitter cold can totally ruin your favorite tomato plants. You wake up one chilly morning to find limp, blackened vines and green tomatoes spoiled all over the ground. All that hard work and care, gone in just one freezing night.

Nobody wants to lose those warm-weather crops to an early cold snap or the first fall frost. But here’s good news: with a little prep and know-how, you can keep harvesting tomatoes right up until winter hits.

This guide shares some smart tips on how to protect your plants from the cold. Find out just how cold is too cold for tomatoes, easy and economical ways to keep them safe, and how to stretch your growing season a little longer.

Give your plants the best chance to ripen those juicy tomatoes before the winter hits.

How Cold Temperatures Affect Tomato Plants

Tomato plants thrive in warm weather, preferring daytime temperatures of 70-85°F (21-29°C) and night temperatures above 55°F (13°C). Once temperatures drop much below this, plants suffer damage in stages:

• 33-40°F (-1 – 4°C) – Frost kills tomato plants. Prolonged exposure causes chilling injuries like wilted, curled leaves and pitted fruits.
• 41-50°F (5 – 10°C) – Flowers drop. Poor fruit set later due to less pollen production. Pitting, spots on fruits.
• 51-55°F (11 – 13°C) – Stunted growth. Increased flower drop. Poor fruit flavor and texture. Lower yields.

The colder the temperature and the longer the duration, the more severe the effects. Even a few hours below 50°F can set back plants for weeks. Protecting against cold is crucial, especially at night when plants are most vulnerable.

Best Ways to Protect Tomato Plants from Cold

Here are both traditional and modern methods for shielding tomatoes from cool temperatures:

Wait for Warmer Weather

• Start seeds indoors 6 weeks before the last expected frost.
• Transplant outdoors 2-3 weeks after the last frost date when the soil has warmed.

Choose Cold Tolerant Varieties

• Early ripening types mature before cold arrives.
• Look for labeled cold-tolerant, cool-season varieties.

Provide Warm Microclimates

• Use large pots to grow tomatoes, moving indoors/outdoors as needed.
• Plant in sheltered southern spots against buildings.
• Grow in high tunnels, cold frames, and greenhouses.

Insulate Plants Overnight

• Drape fabric row covers directly over plants.
• Create tents around plants using wooden stakes and tarps.
• Cover cage supports with clear plastic for the greenhouse effect.

Add Supplemental Heat

• String incandescent holiday lights under covers.
• Position heat lamps nearby.
• Place old blankets or burlap on cages at sundown.

Water Well Before Cold Nights

• Hydrated plants better withstand cold temperatures.
• Water early so soil absorbs before temperatures drop.

Monitor Weather Closely

• Observe forecasts and get familiar with microclimates on your land.
• Be ready to protect plants anytime cold threatens.

Pick Produce Promptly

• Harvest ripe tomatoes just before a frost to extend your season.
• Pull up entire plants and hang them in cool indoor areas to slowly ripen more fruit.

How to Extend Your Growing Season

Here are a few more ideas for safely getting a head start on spring planting and delaying the end of your fall harvest:

Tip	Description
Harden off transplants	Gradually expose transplants to colder temps over 7-10 days before transplanting to toughen cells against cold shock
Use cloches	Cover seedlings with bell-shaped glass or plastic coverings when transplanting to provide portable protection
Install plastic mulch	Use black or red plastic mulch around plants to absorb and radiate heat into the soil
Prune plants	Prune plants lightly and frequently to stimulate new growth that’s less prone to cold damage
Harvest ripening fruit	Pick fruit as it ripens to prevent losing the whole plant if cold arrives suddenly
Overwinter plants indoors	Transplant some plants into large containers to overwinter indoors in a sunny window

1. Harden off transplants:

Before setting out transplants, you’ll want to harden them off. This involves gradually exposing them to colder temperatures over a period of seven to ten days. This crucial process toughens the plant cells against immediate cold shock.

Starting the process is relatively easy: on day one, simply place the transplants in a shady outdoor spot for maybe an hour or two. Over the course of the week, steadily increase both the duration outside and the amount of sun they receive. Ultimately, this cold conditioning successfully prepares the plants to handle transplant shock.

2. Use Cloches:

To provide portable protection during the transplanting phase, cover seedlings with cloches—those useful bell-shaped glass or plastic coverings.

Because they create a mini greenhouse environment, cloches help regulate necessary temperature and moisture levels. These covers, which allow sunlight to enter while trapping warmth, work equally well whether placed over plants already in the ground or those still in pots.

3. Install plastic mulch:

Consider installing black or even red plastic mulch surrounding your plants. Due to their dark hues, these materials effectively attract and retain warmth, radiating heat down into the soil. While providing multiple growing benefits beyond just cold protection, the mulch also conserves essential soil moisture.

One key caveat: Be sure to install drip irrigation prior to laying the plastic.

4. Prune plants:

Light and frequent pruning stimulates the kind of new growth that proves less vulnerable to cold damage. Removing older foliage and spent flowers compels the plants to produce fresh buds and leaves more suitable for existing weather conditions. Additionally, this improves both light exposure and crucial air circulation.

5. Harvest ripening fruit:

When fruit ripens, pick it quickly—this is a preventative measure against losing the entire plant should a sudden cold snap occur. For instance, if frost threatens, harvesting any ripe tomatoes early lets you safely secure your remaining produce.

You can also pull up the plants completely by the roots, then hang them indoors, upside down; this allows additional fruit to slowly ripen off the vine.

5. Overwinter plants indoors:

If you want to overwinter tomatoes, transplant a handful of your plants into large containers that can be kept indoors near a sunny window. Choose the healthiest specimens, ideally those still bearing a few green tomatoes. Containers allow you to continue nurturing selected tomatoes throughout the winter season.

Conclusion

Now you know how to give your tomatoes the warm conditions they love, even in cooler climates. Try out small-scale protection methods at first to see what works best for your plants and property.

Share these ancient Native American secrets with fellow gardening friends and family. Dig in and watch your sacred tomato plants thrive with the right care.