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Weather for gardens

Dr. Leonard Perry, Extension Professor
University of Vermont

If you are interested in gardening, then you are probably interested, at least somewhat, in the weather. Understanding a few weather basics you might encounter while gardening, and how to keep track of the weather, can make your gardening more fun.

Weather is what happens on a day-to-day basis, while climate is the long-term trend over weeks, months, or years. The key to weather is observation. The first meteorologist, defined as a person who studies the weather, was Aristotle. He believed that by observing weather we could track climatic trends.

Observing is what weather forecasters still do today, only now they use more sophisticated instruments and computers. In fact, all the data, and the mathematical and physics formulas or models they are plugged into, require computers to process. The results vary with each forecaster's interpretation and the models used, as anyone who listens to more than one forecast on a regular basis knows.

Some gardeners and growers monitor several forecasts daily, either by television, radio, or the Internet. They then make their own best guess, or take the average of all. The Internet is an excellent source of detailed weather information for your particular area and the whole world! You can access it through Websites of local newspapers, national television networks, special weather channels, some universities, and many private sites. You might try typing "weather" into search engines. Many Internet service providers also offer a link or two on their homepages. These sites often provide, in addition to the daily weather, articles and photos of special weather events such as ice storms or hurricanes. One website I find easy to remember and use is the government one.

The saying that "a little bit is good, but too much is bad" is so true with the weather. Take the sun for instance--the key to all weather. The heating of the sun causes day temperatures to rise and the seasons to change. Differences in temperatures in various locations, or changing temperature, causes our frontal systems and precipitation. Of course too much sun, and also too much heat, can burn some plants, especially if there is little rain or drought. And gardening can cease to be fun if it's too hot to work comfortably.

Couple high temperatures with humidity, and you have the "heat index" seen in weather reports in many southern locations. Your body cools itself by evaporating moisture, in other words, sweating. With high humidity, less water is lost from your body, so it is cooled less, and you feel even hotter. This is the heat index, and when high, can lead to problems of heat stroke or, when caused directly by the sun, sun stroke. One summer, when I was touring the Missouri Botanic Garden in St. Louis, the temperature was 98 degrees F but the heat index was 115 degrees!

On the other hand, couple temperature with wind, and you have the "wind chill index" seen in weather reports in many northern locations. The wind makes your body lose heat faster than normal, and so it seems colder. Although not as important perhaps to most gardeners, as wind chill is significant only in the "off season," it can still be dangerous. Wind chill causes frostbite to exposed skin at temperatures about 20 degrees F below zero. An actual temperature of 10 degrees F with a 10-mph wind will feel like 9 degrees F below zero. No fun when you're outdoors checking shrubs for ice damage and pruning broken branches!

Of course it's the wind, too, that dries out evergreens in winter causing them to turn brown and "burn." Erect burlap screens on the windy side to help prevent this. In the spring and summer, some wind can be good, keeping you cooler and the bugs away. But too much wind can wreck havoc with plants and garden objects, and if continuous, be disturbing. In flat areas such as the Midwestern states where long periods of wind are common, you often see windbreaks of trees near gardens and nurseries.

Here's one more interesting tidbit. Studies have even shown that crime and playground violence actually increase as the wind increases! If you have a garden, you might consider an attractive weathervane to tell the direction of the wind. I like the hand wrought iron ones stuck on a post in the garden.

Lightening is a violent and dangerous weather phenomenon that can kill and does. So, forget the lawn mowing, weeding, or other gardening chores when such storms are approaching. If your garden is fairly open, in a valley, or prone to severe thunderstorms, consider lightning rod protection for tall trees near your home, or if they are valuable. Consult an arborist for advice and price quotes.

Windsocks are attractive and can be used to gauge the direction and speed of wind. You also can buy several types of "weather stations," which when mounted outdoors tell wind speed, direction, temperature, and perhaps rainfall and humidity. Some of these are mini computers, storing information at certain intervals and for weeks at a time.

If nothing else, if you garden and need to know a little about the weather, you might consider a thermometer mounted outside the house and a rain gauge. When mounting the thermometer, pick a location out of direct sun if possible in order to get the true temperature. The better thermometers have a sensor on a long cable, so you can put the thermometer inside and run the cable outside where desired.

I really like the rain gauges that you can monitor inside. These are connected to the actual guage outside by means of a thin wire, or my favorite--the wireless ones. Inexpensive plastic rain gauges also are useful to set under garden sprinklers to check how much water they are really putting on your garden. You may be surprised!

http://pss.uvm.edu/ppp/articles/weather.html

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