What to Do In the Aftermath of a Deep Freeze to Help Your Plants Recover

Winter takes a toll on gardens. When a deep freeze hits, ice crystals that can kill or damage plants form in and between their cells. When the crystals puncture cell walls and membranes, plant tissues turn black or brown and become limp, translucent, soggy or mushy. A deep freeze accompanied by heavy ice and snow can break stems and branches, and strong, cold winds can pull moisture out of plants until they're dehydrated. New growth and buds are especially vulnerable. But don't despair. There are steps you can take --or take later, when the weather improves--to help some plants recover.

1. Let Snow and Ice Melt Off Of Plants

If your garden has taken a beating from the freezing weather, give it a little time before you do anything drastic. Cold damage can take a few weeks to show up, and while some plants won’t make it, others will, so check on them from time to time. It's best to leave any ice or snow on your plants to melt on its own. A deep freeze can make branches and stems brittle and prone to breaking.

2. What to Do as Soon as the Snow Melts

Go ahead and remove new growth, buds or other plant parts hit by a hard frost or deep freeze that have become soft or started to rot or decay.

Cold-Hardy Plants

Cold-hardy plants like pansies and kale can survive freezing temperatures, so they'll usually revive on their own.

Annuals and Vegetables

Most annuals and vegetables will perish in a deep freeze. When the ground is workable again, pull or dig them up and put them in the compost bin. Don't replace cold-sensitive, tender plants until the soil and air temperatures warm up in spring.

Perennials

Don’t be too quick to pull up perennials, even if they look brown, black, scraggly or dead. Some perennials are root-hardy, which means their top growth will die to the ground (usually in autumn), but they should come back from their roots as long as they're rated as cold-hardy in your USDA Gardening Zone.

Some evergreens suffer from winter burn after a deep freeze. Winter burn can occur when it's below approximately 20 degrees F. and the sun or wind strip more moisture from the foliage than their roots, buried in frozen soil, can replace. Evergreen needles or leaves can become discolored, their bark can split, and branches or entire plants can die if the roots are too badly damaged. To aid in their recovery, keep your evergreen plants watered after the soil thaws out and mulch around them to keep the moisture in the ground. Cut away any damaged or dead parts just before new spring growth emerges.

Semi-evergreen perennials can lose a lot of foliage and also look brown or ragged after a deep freeze, but they'll typically survive. If you're not sure about whether a plant is dead or just damaged,, lightly scratch a little spot on the stem or bark with your fingernail. If the tissue underneath is green or moist, the plant is probably alive and should start growing again when warm weather returns.

3. Water at the Right Time

Dormant plants probably won’t need much water, if any, while the temperatures remain below freezing. Other plants need water during the cold season, but much less of it than they need in warm weather. Don’t water when the soil is frozen, or it will run off before it has a chance to soak into the ground. If rain is scarce, give your garden a drink during a period of dry or sunny weather, or when it’s cold and windy, so they won’t get dehydrated. The best time to water is during the middle of the day, when the temperature is above 40 degrees F., so the soil can absorb the water before the mercury drops again. Never let the soil get soggy. Many gardeners water their plants before a freeze is predicted to help trap a little heat in the soil.

3. Don’t Encourage New Growth Immediately After a Deep Freeze

As long as there’s a risk of another hard frost or deep freeze, don’t prune frost or freeze-injured plants. Pruning can stimulate tender, new growth, which can be killed or further damaged by another cold snap. In general, don’t remove dead or dying foliage either; it can help insulate plants and possibly help them survive. Wait to prune until all frost and freeze danger has passed, and then cut back to live, green wood in the spring. Don’t fertilize until the soil warms up or until newly-planted plants have developed good root systems so they can take up nutrients.

4. Help Plants Recover from Winter Salt Damage

If you use a de-icing product that contains rock salt, also known as sodium chloride, the salt can damage your lawn or plants if it runs off it rains, or when snow and ice melt. Salt damage can make grasses and plants wilt, turn brown and dry out, and often leaves a white crust behind. To counter the damage, flush out the salt by watering the affected areas deeply after the ground thaws out, and add compost or other organic material to help rebuild the soil. Some salt-free de-icers are available.

5. Don't Forget to Help Your Lawn After a Freeze

Avoid walking on your grass when it’s frozen, and don’t reseed until after the last spring frost in your area. According to Lawnstarter, a company that connects homeowners with local lawncare professionals, wait until the soil temperatures stay above 50 degrees F. for several consecutive days before you sow cool-season (northern) grasses. For warm season (southern) grasses, wait until it’s at least 60 degrees F. for a time. Then learn how to get grass green and growing in spring.