This week our family friend Charles Bragdon arrived on his Massey Ferguson tractor with a moldboard plow attached on the back. The plow is rusted here and there – it’s obviously seem its share of acres over the years – but as it cut through the soil, expanding once again my ever-increasing garden plot, we watched the layers of sod fold over like velvet. Deliciously green grass instantly turned to rich, russet-brown earth.

Charles carefully pulled the plow through the soil with perfection, precision. Then he backed up, setting over to plow the next furrow. The disc on the front of the plow plunged into the sod, cutting a neat, sharp track for the blade to sink into. We all stood and watched, practically entranced by the rhythmic beauty of it all.

I would make this scene last a long, long time if I had my druthers, but one thing spoiled the brief gardener’s dream: the late afternoon sun. It beat down on the soil, turning in short order the beauty of the velvety earth to, shall we say, the look of tattered burlap.

Albeit a necessity to our dear garden plants, the sun’s powerful rays are a force to be reckoned with. The speed with which the sun draws moisture from freshly turned soil is a reminder of its awesome power. In spring, tender little seedlings need our help in acclimatizing from the greenhouse environment to the outside world. A host of environmental impacts are wrought on newly transplanted seedlings, but the sun is perhaps the greatest factor to contend with.

A bit of knowledge of the biochemical and physical qualities of plants and water can aid the gardener in easing the transition of plants from the protection of the greenhouse to the wild world of the garden.

First, it’s important to note that although water is taken up in great quantity by plants in general, only a minute fraction of that water is actually used and absorbed by plants for growth processes. This fraction of water is used mainly to help keep cells swollen or turgid. The internal water pressure of a plant is called turgor pressure.

A much greater percentage of the water is simply lost by the plant through evaporation or through a process called transpiration. Through transpiration, water vapor diffuses into the air from tiny holes in the undersides of leaves. When adequate moisture is available to plants, they generally are able to retain their turgor pressure. When inadequate soil moisture is present, when there is a water deficit within the plant, wilting happens. Scientifically speaking, wilting results when the loss of water through transpiration exceeds that of water replacement by the plant through absorption from the environment.

Wilting can simply be a temporary stress on plants or, in extreme cases, it can be the cause of a plant’s death. To reduce the risk of wilting, a gardener can improve the water-holding capacity of their soil. The addition of organic matter, in the form of garden compost, composted manure or peat moss is an excellent way to increase the water-holding properties of any soil, be it loam, clay or sand.

Naturally, for most plants the rate of transpiration is greatest during daylight hours. With the setting of the sun, the demands on plants relax, and so does the rate of transpiration. This little tidbit cues the gardener that irrigating plants in the evening is perhaps a wiser practice than watering during the height of the day. Watering in the evening allows plants to absorb without such heavy biochemical or biophysical demands.

Finally, mulching garden crops is another great way to reduce the risk of losing soil water to the sun and to increase the value of irrigation. Mulch is a shield against the penetrating and soil-water-evaporating power of the sun. Whether a thick layer of organically derived mulch or a thin layer of plastic, all mulches serve the same function: To limit or reduce the pathway of water loss from the soil through evaporation. As a result, water is made available to plants when they are in need. Apply this inexpensive and protective layer to your crops immediately after planting and reap the rewards all summer long.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, RR1, Box 2120, Montville 04941, or e-mail them to dianagc@ctel.net. Selected questions will be answered in future columns. Include name, address and telephone number.