Coping with Winter – Part 2

Robin Stanley – U.C. Master Gardener

In Part 1 on this two-part article, we covered ways to prevent frost damage and what you can learn about your property from observing the patterns of frost damage. In Part 2, we’ll be discussing the best ways to deal with frost damage that may have occurred earlier this winter and how to prevent further damage.

As this article goes to print, the weather is beautiful and sunny – it’s perfect winter gardening weather in El Dorado County and it’s tempting to think that spring is just around the corner. But more freezing weather is in the forecast so there is still potential for additional frost damage to plants. Let’s talk about what gardeners can do to keep frost damage from getting worse.

You probably know how to recognize frost damage in most plants. You can see dieback of leaves, stems and shoots. You can also observe the drying, blackening and death of fruit, flowers and dormant flower buds. It’s not pretty; the damage may affect the entire plant or only a part of a plant.

The temptation can be to prune out the damage. The enthusiastic gardener wants to make the plant more attractive and hopes that cutting off the damaged parts can invigorate the plant. But wait! Pruning now can encourage further frost damage in the weeks and months to come. Pruning too early can stimulate new growth; these tender new shoots are particularly susceptible to frost and can move the frost damage further into the main part of a plant. Leaving the frost damaged leaves and stems on the outer parts of the plant can actually help to insulate the plant by helping to trap warm air around the plant. While it’s not attractive, this mass of leaves continues to protect your plant.

But that’s not the only reason to hold off on removing frost-damaged plant parts. Frost damage can be deceptive. You may think damage is worse than it is. You might be surprised in a month or so when the plant starts its spring flush of growth. New growth can sprout from stems that looked dead. On the other hand, you may have been too optimistic and will see evidence of frost damage you overlooked earlier. Don’t prune until new growth begins and you can see for sure what parts of your plant survived. Otherwise, you might prune too severely and ruin the shape or vigor of your plant.

Research from the Terry Mikel at the University of Arizona indicates that “the more severe the damage, the longer it takes for the older buds to emerge. Young, undamaged buds break and grow early. Buds laying in older parts of the plant need more warmth and stimuli to begin to grow.”

When it really is time to prune, you’ll be glad you waited and hopefully be rewarded with vigorous new plant growth. Don’t fertilize until after this well-timed pruning; earlier feeding will encourage new shoots before the weather is right.

In some plants, dieback can go all the way to the ground, with plants sprouting back at the soil line. If you have grafted plants (like some citrus or roses), pay attention to the origin of these new sprouts. If they are only coming from below the graft line (the dividing line between the top part of the plant and the rootstock to which it has been grafted), the re-growth will represent the rootstock only. Rarely would this growth be a productive plant or an attractive addition to your garden. You can re-graft onto the rootstock or decide to replace the entire tree or plant.

As was mentioned in Part 1 of our “Coping with Winter” discussion, there are lots of things you can learn from observing where frost damage does or doesn’t occur. Plants in areas that get a chance to warm during the day can use some of that warmth to protect them overnight. As the sun gets higher in the sky, the warm and cold locations on your property may be changing. Gardeners with large trees might find that their property’s coldest locations may have shifted from December to February.

Remember that anything you can do to warm your plants is beneficial. While winter mulch is advised for eastern and northern climates that stay cold all winter, mulch in the foothills can actually prevent daytime warming of your soil, thus making it harder for the plant to retain heat. If further frost is predicted, plants can be covered. Be careful to keep the covers away from contact with the plant.