Staying Warm (or Keeping out the Cold)
5:42 pm December 16th, 2008There are two kinds of cold that affect gardening. The first is obvious because we are daily reminded by the radio and the T-V. of air temperatures. The second is often overlooked and that is soil temperature. At this time of year we need to know what is happening in both cases and to take steps to avoid damage to our plants.
Location determines the onset of cold temperatures, gardens that are on the edges of washes ( as with our garden at Sabino Vista) collect cold temperatures because cold air moves downhill, just as water does. If it collects there because there is no outlet, such as a wall, our plants will be sure to freeze. Cold air that is moving is less damaging than stagnant cold air. Gardens that are situated on sloping ground that allows air drainage are less likely to have frost damage. South facing slopes are better than northern ones because the sun strikes the soil at a better angle and, of course, gardens in the shade are lnot likely to warm up during the day.
Cold winds from the north bring in freezing temperatures and there’s not much we can do about that except to be ready for them. Listen to the weather reports, have sheets ready to cover sensitive trees like citrus and if the weather is going to be cold and long-lasting have a heat source to put under the trees. A 60 watt bulb in a bucket with a complete covering of the tree with a sheet will protect fruit and leaves. For ground vegetables a covering of a sheet, a frost blanket (from nurseries) or even layers of newspaper will trap the previous day’s warmth from sunshine. These coverings should be taken off during the day and put back on before the sun goes down. It’s a chore that few of us enjoy doing, but bear in mind that one night of frost can destroy weeks of good gardening.
The dangerous situation to look out for is several days of cloudy weather followed by clear night skies. Heat from the earth radiates up in our clear desert skies but if the nights are cloudy it’s not likely to be a frosty night
We want the soil to be warmed as much as possible during the day and that’s why we should abandon the use of summertime mulches that stopped our soils getting too hot.
A way to preserve our plants from air cold and soil cold is easily done by creating a miniature greenhouse over our garden plot. Several gardeners are doing this with wonderful results. You need some pliable wire hoops and some clear plastic. See pages 15 and 257 of my book which have pictures for you to help you get the idea. You may need to open the ends of the tunnel on hot days to dry out the atmosphere inside. Otherwise you’re creating a good environment for aphids and fungi. Humidity inside a tunnel condenses on the cold plastic and falls down to the soil saving water from the drip irrigation, which sometimes needs to be turned off.
All this hazardous cold weather comes to an end in mid-March when seed sowing and planting out can be resumed. However, don’t be in a hurry but wait for the soil to be properly warmed. Look at the chart on page 172 that tells you the optimum soil temperatures for the start of your springtime activity. Soil thermometers are cheap and available at hardware stores and nurseries. They make a good post Christmas gift for the Gardener You Forgot..
Some gardeners have been misled by the Newsletter’s Planting Guide when it says to sow seeds of tomatoes in January. Sorry about that, but what is intended is to get you to sow seeds indoors, ready for setting out plants in your garden in March