In October, the NOAA (National Oceanic and Atmospheric Administration) forecast a warmer than normal winter for our area. That’s not good news for us gardeners, or for our woody plants!
Why warmer weather isn’t better
Our shrubs and trees struggled all summer—and now into the fall—with higher-than-normal temperatures and lower-than-normal moisture. Once cooler weather arrives, even short increases in temperature can cause buds to break dormancy. And lower-than-normal cold snaps that accompany our increasingly irregular weather make things worse.
Which woody plants are most vulnerable?
Plants aren’t equally sturdy. Make sure you know what shrubs and trees are in your landscape, as well as their specific requirements. Many popular landscape choices are only marginally cold hardy here in the mountains and your terrain has a lot to do with cold hardiness. Cold air settles in low-lying areas of your yard. Whether a plant is on the north versus south-facing side of your home and has or doesn’t have protection from winds all affect how your plants fare. Evidence is mounting that woody plants with less chlorophyll (green) associated with the foliage—those that are variegated, gold, or purple—are less vigorous than all-green parent species.
What can you do?
To protect your plants from those freeze-thaw cycles—as well as the sunburn, wind, snow, and ice that really do the damage, particularly at higher elevations—you need to provide some additional layers. For plant roots, a good layer of mulch is an appropriate defense. Mulch doesn’t keep the roots warm, but it does protect them from temperature extremes that come with the ground freezing then thawing.
Similarly, protect the upper part of a tender plant by surrounding it with a “blanket.” Drive stakes into the ground around the plant and staple burlap to the stakes. Stuff the spaces between the branches with pine straw. The intent is to keep the plant cold on warm days, rather than warm on cold days. This keeps dormant plants dormant! Avoid using plastic, which traps heat, causing temperatures to rise well above the temperature of the surrounding air.
For evergreens, burlap may help protect from sun- and windburn. Anti-desiccant sprays purport to provide protection, but it may be short-lived. Making sure the roots are well-watered is a better plan to prevent woody plant loss.
Article written by Glenn Palmer, Extension Master Gardener Volunteer.