Flood and drought are overlapping weekly this summer in Virginia’s southwest piedmont. Gardens may be withering on one side of the house but deluged and drowning on the other. What’s a gardener to do?
Remember this: it’s a marathon, not a sprint.
Remedies that look to the long-term are being presented this month as the Patrick County Master Gardeners launch a waterwise educational series. It began on Saturday, July 16, at the group’s Learning Garden on Tudor Orchard Road, under the guidance of Ed Coleman. The program included Norma Bozenmeyer discussing the importance of monitoring water quality, and Kurt Bozenmeyer’s demonstration of rain barrel construction.
It will continue on July 26 with John Morehead’s regular WHEO radio program, featuring ways to use less water in your garden.
The series will round out on July 29 at the Stuart Farmers’ Market when Sherry Easterbrooks provides displays and informational handouts on low cost/low tech techniques for using less water and how to develop a plan for your patio, garden and home. That may be a lot to assimilate in one morning, so Dee Nolan will lead a special activity for the kids to keep them busy while their parents gather the information they need.
In general, a garden needs about an inch of water a week. That calculates out to about 0.6 gallons per square foot, according to Julie Shortridge, an Extension Specialist in the Department of Biological Systems Engineering at 
Virginia Tech. So, an 8-foot by 2-foot raised bed (that is, 16 square feet) needs roughly 10 gallons per week.
But there are a lot of variables, including the condition of the soil and the growth stage of the crop being raised. Soil type dictates the maximum amount of water a soil can hold and how much of that water will be available to plants. Fine textured soils can hold more water than coarse textured soils. Even so, a half-inch shower could be problematic. Water must penetrate 5-6 inches into the soil for the roots to get their fill. On those occasions, consider watering more right away to push water deeper and keep roots healthy.
Most vegetables’ water needs peaks as the plant flowers and begins to form fruit. Beets should be watered sparingly during its early stages so that the water and nutrients are not spent on lush foliage rather than well-rounded roots. Carrots need a steady relatively high amount of water throughout; letting the soil dry out as you might with beets will cause carrot heads to split. Corn needs little water as it first grows, then more as tassels form and silk emerges. That done, its need dips for a bit, then resurges as the kernels begin to swell.
Water at the soil level if you can. Even though it imitates rainfall, water sprinklers invite the possibility of foliage remaining wet long enough to invite leaf disease.
Mulching is especially important in dry situations. They reduce moisture loss through evaporation and keeps the ground cool enough to limit transpiration through the plant’s leaves. Be sure the mulch is on top of the soil; don’t mix it in.
Weeks that feature too much rain offer both a present danger and an opportunity for future dry days. Unchecked, a large volume of stormwater can increase erosion; push pollutants and debris into streams thus increasing the likelihood of flooding; and degrade water quality in general. Grass swales, rain gardens, buffers and permeable pavement will help decrease that runoff.
Use those weeks when there is rain to prepare for the dry days. There’s a variety of methods, mainly rooftop redirection (gutters and downspouts), rain barrels and cisterns. And there are many tips for making the most of these tactics.
Tip: Place your rain barrel near the area that you plan to water. Water is heavy; one gallon weighs 8.34 pounds. A 45-gallon barrel will weigh 375 when it’s full.
Tip: You’re likely to get more rain from the roof than you can handle with one rain barrel, cautions the stormwater management team at Virginia Tech. A thousand square-foot roof will shed 600 gallons of water in a 1-inch rain. “That’s about 12 barrels, so always plan on how to handle the overflow.” Solving the potential problem does not end with an overflow device near the top of the barrel. The real question is where all that water will go from there. You’ll also need to look at other methods of guiding the excess to an area where it can be slowed enough to be absorbed into the ground — to a rain garden, swale or riverside buffer for instance.
Tip: Clear overhanging tree branches from above the roof. This helps diminish downspout clogs by leaves and twigs as well as water pollution from bird droppings.
Tip: Sidestep problems posed by algae and mosquitos. Painting a rain barrel black will block sunlight and help prevent algae growth in the water being held. Fine mesh screen over openings to the barrel or the introduction of Bacillus Thuringiensis Israelensis are good preventatives, available at most big box stores under a variety of brand names.
Rainwater harvesting into underground cisterns allows for collection of much larger volumes of water. Some have capacities of more than 14,000 gallons. Thus, protected from freezing, cistern water can extend to year-round use and go beyond the garden to flushing toilets, washing cars, etc.
Just as with rain barrels, the gathered water is not potable; overflow needs must be accounted for and there are maintenance practices that must not be ignored. Cleanliness is important in both cases: clear gutters and downspouts of leaves and debris, including pollen; inspect and clean lids, inflow/ outflow/ overflow devices, mosquito screening.
Installing a rainwater harvesting systems and their accompanying buffers, swales and rain gardens will do more than keep your garden healthy and prevent erosion in the yard. It also protects downstream waterways from the effects of nutrients — especially nitrogen and phosphorus — from creating algal blooms and dead zones downstream.
