Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
January 31, 2012
It has certainly been another unusual winter in a series of several. Sixty degree days at the end of January certainly haven't been the norm, but we've been in a series of hills and valleys for quite some time. One of the most common questions is "Will this weather, followed by cold weather, harm my plants?" You can probably guess the response: "It depends."
One of the main things that "depends" is how quickly the weather returns to more seasonable temperatures. A quick cold snap would have much worse effects than a gradual cold trend. Any time we have sap in the trunk or branches of trees and shrubs, then get a cold snap, we can have trunk and branch damage show up as frost cracks. This is similar to a bottle of water freezing, and then it has to pop open somewhere. Frost cracks are not very damaging to plants. Our main hope is the flower buds on the sweetgums are damaged!
Flower buds are probably most at risk. We can live without a few flowers on flowering shrubs, but this can also mean lower fruit production on many of our fruit trees. The length of time for the warm weather will determine how many of the fruit and leaf buds start to initiate development. In general, a warm winter means the fruiting buds on tree fruits and grapes will not withstand cold temperatures as well as normal.
As for the small fruits, more can be at risk for raspberries and blackberries. They may have already met their cold requirements and begun bud swelling. A cold snap could cause canes to die from the top down. This might mean the loss of the summer berry crop, but new canes should emerge in the spring. Blueberries should be unaffected by the warm temps, and strawberries with a straw mulch should also be insulated from the warmth. The straw really helps keep them from breaking dormancy too early.
The warmer weather may be a benefit for lawn as it is encouraging root growth in existing lawns, and it really helping newly seeded or sodded lawns. The downside is a quick drop in temperatures may heave plants out of the ground, shearing off roots. Also, avoid walking or driving on lawns until soils dry out and spring growth begins in earnest.
Perennial flowers have been "messed up" all fall, with many of them trying to flower between Thanksgiving and New Year's. Most all are going to survive just fine, but the flowering part may take a year off if flower initiation did begin.
"It depends" goes on and on. A snow blanket will also provide insulation against a cold snap, but not many are wanting snow after the rather mild winter we've enjoyed. The weather may remain mild, and we will not experience any problems. Or, most likely, the weather will remain unstable. Then we will see what happened, and we will live with the cards dealt by Mother Nature.