This weekend I’m finally going to plant garlic. Ideally, it would have gone in the ground sometime between mid-October and Thanksgiving, but here we are. Even though flurries are flying past my window this morning and it’s in the mid-30s, my weather app says it will be 60 degrees this weekend. The worst thing that will happen is that my garlic harvest comes in later in the summer and I lose the opportunity to plant something in its spot in the garden in July.
Recently I’ve seen forsythia blooming and daffodils shooting up. I’ve been told about roses and lilacs blooming again in November and fall-planted garlic bursting through. This is called “breaking dormancy,” and it happens when plants are triggered by temperature and environmental conditions to develop buds for leaves and flowers and for new growth to occur. In our climate, that should happen in the spring after a seasonal period of rest when no growth occurs for plants, woody plants and trees. Here that period is fall and winter. This is not a typical habit for our local foliage.
The newly revised hardiness zone climate map was released this fall by the U.S. Department of Agriculture (planthardiness.ars.usda.gov). As I’ve written before, this is a guide for plant survival by modeling the coldest temperatures the plants have to survive. It was last updated in 2012 and demonstrates that overall temperatures are 2.5 degrees warmer since then. About half the zones in the country moved up half a zone.
Locally, Cold Spring, Garrison and Beacon are all listed in Zone 6b, which indicates the coldest temperatures should be in the minus 5 to zero range. In 1990, Cold Spring and Beacon were in Zone 6a, with the lowest temperatures dropping to between minus 5 and minus 10 degrees. Garrison has been in Zone 6b since 1990.
Within these zones are microclimates in which it will be warmer or colder depending on environmental and geographic features, such as proximity to water, elevation, ground surface and the direction a slope faces. Take the hardiness-zone information as a guide, then factor in your observations for a closer understanding. For a fuller discussion, see highlandscurrent.org/your-zone.
What I found particularly interesting was an explanation of hardiness-zone shifts in a discussion about climate change published by Yale Environment 360. Its research showed that plant zones are changing at a pace of about 13 miles per decade. Consider, for example, that Croton-on-Hudson, which is 25 miles south of Cold Spring, is Zone 7a, meaning the coldest temperatures are zero to 5 degrees. If this pattern holds, Cold Spring will be in the warmer Zone 7a within 20 years and Croton will be in the warmer Zone 8a.
These changes mean there is an opportunity to expand the growing season and types of plants that can thrive. At the same time, it means that some plants and trees won’t get enough cold days at low enough temperatures to survive. Episodes like breaking dormancy and blooming offseason — that forsythia I saw is blooming four to five months early — will be more common.
In addition to garlic, unfrozen ground can be planted with other bulbs, and certainly broadleaved trees. Avoid planting evergreens until spring because they are more prone to drying out in winter, and if temperatures are shifting up and down, dormancy will be harder to evaluate.
According to Shane Stevens, the master-forester volunteer coordinator for our Cornell Cooperative Extension region, best practices are planting trees in dormancy. We most typically think of that as spring or fall but the unfrozen soil has created a longer opening. “When I planted trees with the Greene County soil and water conservation district, it was less stressful for the tree if it was being manipulated during dormancy,” he said. “Our success rate was lower for trees planted in mid-summer and we tried to avoid it.”
Follow all the usual best practices for planting and be prepared to water it and continue watering during a dry spell if the temperatures rise. Mulch is especially important during winter planting because it will help maintain the soil temperature as air temperature fluctuates.
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