During our holiday preparations in December we had a little taste of winter with some night time temperatures dropping below freezing. As the new year emerged, we were greeted with an arctic blast that swept across a number of northeastern states and Long Island. That blast brought along some pretty cold temperatures, dropping them into single digits and lasting for close to two weeks.
During that time, many evergreens were damaged by the extended cold. If you've happened to look closely lately you’re likely to notice brown, dry, dead leaves on hollies, rhododendrons, Schipp Laurels and other broadleaf evergreens. Because the temperatures didn’t get above freezing for an extended period of time, many leaves were dessicated by the harsh conditions. It’s likely that more damage may emerge as the plants come out of dormancy and it’s not uncommon for the symptoms to be disguised on rhododendron. As their metabolism increases with longer days and warmer temperatures, the damaged tissue will respond and shed itself from the plant.
What Is Desiccation?
Technically speaking, desiccation is a state of extreme dryness or the process of extreme drying. It occurs in plants because plants continue to transpire moisture and aren’t able to replenish it. The constant vacuum that pushes moisture through the roots, into the branches and out through the leaves is disrupted. The leaves die back as a defense mechanism to assure the plants survival. Plants have tolerated these conditions since the beginning of time and this is one of the reasons they have evolved into deciduous species that drop their leaves each year. They’re protecting themselves against the harsh conditions of winter.
This is a serious concern as the plants that are most affected are often functional components of the landscape; they provide screening and interest to our winter landscapes. Now we’re looking at plants that appear dead and that's not what we had in mind when we planted them. Unfortunately, this is part of managing a landscape and it’s also a big reason why we maintain our plants through the growing season. Healthy plants will survive the damage. Any plants that were in a declining state may succumb to the “straw that broke the back”.
Diagnosing The Damage
The first thing to do, is look closely at the very end of the branches that have the damage. Look for the tight buds that grow at the very tip of the branch. Don’t damage the bud by squeezing or pulling. Just make sure it has the proper color. You’ll know if it’s alive or dead by looking. If the bud is viable, this branch or section of the plant will recover. If the bud is dead (brown and dry) you’re likely going to lose the entire branch. In very bad conditions, it’s common for entire sections of a plant to die back. Remember that the plant knows what to do to recover from this stress but y ou may want to consider an anti-dessicant treatment to protect the plant for the remainder of the season.
Treating The Damage
Based on my experience, I believe most of our damaged plants are going to recover. There will be some damage to tend to in the coming season and overall this isn’t as bad as other years I’ve seen. We still have 6 weeks of winter conditions and the process could occur again. Its the longevity of the cold temperatures that determine the extent of the damage. I’m not a proponent of wrapping plants to protect them however it works similar to an anti-dessicant by preventing friction on the leaves as the wind blows over the surface.
Be patient, the plants won’t recover in 1 or 2 weeks. Most evergreens push their new growth in May. As the new tissue emerges, the dead tissue will drop to ground. I don’t recommend doing any pruning now. It’s likely that you’ll cut viable tissue off the plant. Leave as much of the existing branch on the plant and allow the plant to determine what’s going to go and what should stay. Any pruning you do to improve the aesthetics should occur in late April.
Don’t forget that the plants have been compromised. This damage is a strain on the plant. Plan on applying an organic, slow release fertilizer in April to help the plants do their job. Keeping the plants healthy is our responsibility and fertilizing should be a component of every landscape maintenance program. Make a commitment to maintain your plants this year. Just follow the basics; the staff at Decker’s Nursery & Florist is always happy to help you.