NOAA‘s one-month weather model predicts warmer-than-average temperatures for the Northeast; the three-month model predicts both above-average temperature and precipitation. Many people are enjoying the warm weather we’ve had this fall. From a horticultural point of view, however, a warm winter is a disaster for a number of reasons.
First of all, fooled by the warm weather, many woody plants are showing swollen buds if not actual flowers. My lilacs, fooled by the warm temperatures, are making faint efforts to bloom right now. Any energy a plant expends now is energy it will not have in spring, and worse case, plants can be killed if they leaf out before a sudden cold snap. Expect a less-beautiful than normal spring.
Second, a mild winter will mean large populations of deer and rabbits next season. The last time we had a very mild winter, the critters repeatedly ate many perennials down to the ground: phlox, asters, and boltonia never bloomed that year. The past two cold winters have finally given the plants time to recover.
Third, insect pests and diseases will be more prevalent than usual after a mild winter, because cold weather kills off fungal spores and insect eggs. In particular, the last two cold winters slowed the steady advance of pests that are moving north along with global warming, such as the southern pine bark beetle. A warm winter will allow them to resume their northward advance.
And last but not least, a warm winter will encourage the northward march of many invasive plants. For example, butterfly bush is now highly invasive in Pennsylvania and southern New Jersey and is becoming a problem in our area. Miscanthus grass is extremely invasive in North Carolina, Virginia, Maryland, and Pennsylvania. How long do you think it will be before it becomes a serious problem here as well?
Sure a warm winter brings some benefits: lower heating costs, less snow removal, less salt on the roads, less danger of accidents. But it’s not all good!