Reviving Frozen Plants

After The Freeze

As a series of cold fronts ripped through the Northwest, many of us struggled to shelter and protect borderline hardy plants. Draped with floating row cover cloth, sheets, or bubblewrap, temporary structures can provide a few degrees of frost protection, but when the ground is frozen, plant roots will certainly be affected. In many areas, the good news is that the ground was well saturated when the freezing weather arrived. Plants that are hit by a freeze when they and the ground are dry can suffer far more damage than those that are fully hydrated. However, prolonged freezes can leave evergreen plants freeze dried. Thus, when low temperatures leave the garden looking hammered, the first thing to do when a thaw sets them free is to water. Don’t be tempted to overdo it, though, since soggy soil can encourage root rots. If the freeze is broken by natural rainfall, you won’t need to water, but if a dry freeze thaws into dry, sunny days, do provide those poor plants with some relief.

Hardy perennials and many grasses will be just fine, though anything borderline tender that was cut back in autumn may not recover. It’s wiser to leave grasses alone until late winter or early spring; when you see new growth rising from the base, cut back the old stems to just above the green. Grasses that get a buzz cut in fall can rot away in a wet or very cold winter. With evergreens plants, the full extent of frost damage might not be immediately apparent, as deep tissue damage may not reveal itself until warmer weather arrives. It’s very tempting to start pruning off obviously dead stems and leaves, but resist that temptation. We may well get more deep frost before spring arrives and that dead material is all that protects possibly living tissue from another round of cold. Plants will do their best to heal themselves, so wait until March or even April to see what really happened.

Resisting Cold With Natural Sweetness

Winter kill comes in many forms, from root rots to exploding tissue. When warm sunny days encourage sap to rise, freezing nights can freeze that sap, which then bursts plant cells as it expands on the next sunny day. In drier situations, freezing pulls moisture from plant cells, leaving them freeze dried. Many plants have some degree of protection from this process because they create their own natural anti-freeze. Plants store sugars to nourish them over the winter and these help resist freezing as long as temperatures are over about 20 degrees F. Below that point, some plants can change up their biochemistry to keep their circulation going even in deep cold. Those that are acclimated to annual freezing can retreat into dormancy, slowing down their respiratory and nourishment cycles.

For the most part, our wisest choice is to do very little. Don’t prune, since removing dead bits only exposes any living tissue to more damage when the next frost hits. And definitely don’t feed anything, since it will do not good and may do active harm. As plants thaw, they do their best to restore themselves. Evergreen perennials that lost top growth may reappear and slowly rebuild strength; don’t let them bloom this season, though, as that takes a lot of energy that would be better directed toward rebuilding foliage and a root system. Woody plants may also lose top growth but some may sprout from the base or low on the trunk. Such new growth will appear by early summer if it’s going to, but in some cases, the new growth will be weak and very small compared to typical healthy growth or leaf size.

Hold Off On Fertilizer

Don’t try to feed winter damaged plants to encourage this new growth, as impaired foliage and roots often can’t process extra nutrients well. In fact, too much fertilizer too soon can kill fragile recovering growth, especially high-number commercial fertilizers. Instead, mulch with mature compost and wait until strong new growth appears before offering additional fertilizer. If new growth does look good, then do a little judicious feeding over the summer, using half strength fertilizer monthly but backing off in September so any new growth can harden off properly well before another winter arrives. A balanced 5-5-5 will provide plenty of nourishment without forcing overly lush new growth that can’t be well supported by a root system still in recovery.

Lawns may also be affected by a deep freeze, especially if the ground was already dry when the temperatures plummeted. Fescue lawns that usually remain green all winter may go dormant during a prolonged freeze and they too should be treated gently while convalescent. Leave the lawn alone until March, then rake in half an inch of mature compost, which will help eliminate any thatch build up. After a few rains, you can feed with a balanced 5-5-5 fertilizer and start mowing as needed. If you’ve been using a weed-and-feed product, just stop that; stressed lawns can be further harmed by the pesticides (and so can water and air quality, as well as the worms that keep our soil healthy, and birds, and fish down the line).

Evaluate And Act

By early summer, it will be obvious which plants are not going to make it. How long you wait to replace them depends on your own sensibilities; I used to nurse the winter wounded along well past the logical point of acceptance. These days, I’m far more apt to hoick failing plants out and consider well before planting the same thing again. Years ago, I found this very difficult and finally had to start leaving tags of dead plants in the ground to prove something to myself. I’d fall for a beloved plant yet again, bring it home, decide where it would look marvelous and then be bummed to discover a tag for that very same beauty right where I wanted to put the new one. Oh. Well, what about over here? Oh. Another tag. Hmm.

Maybe it’s a dawning maturity, maybe I finally got tired of my own stubbornness, but these days, I no longer try to please plants that can’t thrive in my gardens. Instead, I comfort myself by growing some of the thousands of plants that will happily grow in the conditions I can offer them. Frankly, I’m getting older and finding that I can’t spend a full day in the garden without some payback from my body. I’m finding plants that don’t need me very much far more appealing than those that dwindle or disappear. And happily, this new maturity assures me that reliable plants need not be boring or less lovely than elusive border beauties that are both costly and demanding. Sad? Not at all. In fact, the garden feels even more joyful to me when I’m not constantly mourning the dead. Onward!