I have a garden in back of our house and I love it. It’s just a small 10x20 plot, but I still get a lot out of it. Right now I’m harvesting radishes, beets, and lettuce. Latter this spring I’ll plant corn, squash, peppers and, the pride of every gardener, tomatoes.
Gardening is a hobby I picked up from my father, who was probably the most enthusiastic gardener you’d want to meet. We lived on what had been 76 acres of a farm that had at one time been the home of chickens, hogs, and at least a half dozen head of cattle. My father tilled a large plot behind the cattle barn that his father had built. Choosing among several varieties, he planted at least 40 tomato plants every year. Forty plants. And that was just the tomatoes. We also planted several rows of early corn, sweet corn, and late corn. My mother would be busy for days pickling the cucumbers from our garden, and I remember the dozens of quart jars of the preserves being stored away in our basement.
I helped my father with the planting, hoeing, and harvesting of the garden’s fruits and vegetables. Besides the smell of manure and pounding tomato stakes into the ground, one thing I remember was how attuned my father was to the time of the season and the weather. Week by week he knew when the chance of frost had abated and when to harvest the potatoes. He was also mindful of the variations each year presented, whether the growing season was cooler, warmer, or wetter than average. He also noticed if pests were growing more or less abundant.
This gardener’s mojo isn’t unique to my father. Most gardeners get some sense of it; serious gardeners live by it. Gardeners understand the weather trends and have an understanding of what it means for their beans, strawberries, and potatoes. That’s why the map below, the Plant Hardiness Zone Map, the map planters use to determine the best times to plant their vegetables, is no surprise to folks like my father.
The map has changed since the USDA published the last version of this map in 1990, and it shows a great warming trend across the U.S. What is a bit surprising is the extent of the warming indicated by this map. Divided into 13 zones by their lowest average annual temperature, each region, on average, advanced about half a zone since 1990. This is equal to a five-degree increase in the average minimum temperature. Some regions have changed to show a ten-degree increase. The USDA cautions that some of the changes in the map are because of better data collection, but it is still indisputable that spring thaws are earlier and those first frosts are happening later and later in the fall.
The Farmer’s Almanac, which has been published since 1792, also confirms this trend. Janice Stillman, the almanac’s editor, says, “A lot of folks who garden have noticed over several years that certain plants are blooming earlier in the season. People are noticing there’s a change in the weather.”
So what do people think of this? Can folks read about temperature increases of five to ten degrees all across the country and dismiss global warming? And for those who acknowledge that the world is warming but it’s not enough to worry about, five to ten degrees is a big shift on a thermostat. Now that global warming has gone from the work of researchers measuring CO2 on Hawaiian mountaintops to something that I and thousands of other gardeners who try to time when to plant the lettuce and rutabagas, it’s time to stop the discussions and start doing something.
ref: Jason Koebler Gardening Map Changes For Global Warming US News and World Report 1/26/2012 http://www.usnews.com/news/articles/2012/01/26/gardening-map-changes-for-global-warming