Balance is key to nursing lawn and garden through dry spell

September 28, 2010

Penn State expert says balance is key to nursing lawn and garden through dry spell

University Park, Pa. -- Pennsylvania's recently declared drought watches and warnings present a dilemma for the state's home gardeners and professional landscapers: How do they satisfy thirsty landscapes and the state Department of Environmental Protection (DEP) at the same time? A horticulturist in Penn State's College of Agricultural Sciences said that any drought tactics should start with "balance."
The hot, dry summer led DEP to issue a drought warning for 24 Pennsylvania counties -- particularly in the southwest, south-central and eastern portions of the state -- and less severe watches for the remaining counties. James Sellmer, associate professor of ornamental horticulture, said it's possible for gardeners to meet their water-conservation responsibilities as they sustain shrubs, trees and gardens through this unusually dry period.
"Reducing our water usage is fair to the community to assure that everyone has water," said Sellmer. "We have to balance that with assuring that the new lawns and plant materials that we've put in this summer receive water. This is the time to be serious about your water consumption but also to balance it out so that the plants that you want to survive have a chance."
Sellmer said recently seeded or sodded lawns, new trees, shrubs, herbaceous perennials or bulbs that have been planted since springtime should get a good, soaking watering at least two times a week, putting an inch of water on and around the base of the new plants.
"Prioritize your garden and landscape and focus on your newer plantings -- give them a chance to get established," he said. "You want to make sure that the new seed and sod get a chance to establish their root systems. Make sure that they're getting a good soaking and not just a little sprinkle of water. A good soaking will assure that they survive this dry period."
Unless they're showing signs of severe drought stress, older trees and shrubs that are established are probably drawing water from deep in the soil, Sellmer noted. "Irrigating a part of the root system of an older tree under extreme stress might be appropriate, but only if it's showing signs of damage," he said. "If it's a lawn that's several years old and is well-established, it'll just go dormant and wait for rain, so irrigation is really a waste of water."
Sellmer offers four tips for reducing water consumption while nurturing your landscape:
-- Water deeply, slowly, less often. "Because of the drought, you're looking at soaking the ground with a good inch or 2 of water every few days," he said. "We've been hot and dry since June, so you have some very dry soil, and it'll take a substantial amount of water to soak in and get past the dry layer that's on top right now. Rather than a quick splash-and-go that just gets the top wet, make sure that you've penetrated through the mulch and into the ground. I still use my fingers or get out a little knife and dig down to see if I've gotten deep penetration. Watch the rain amounts and supplement. If you've gotten an inch of rain, you can wait a day or two."
-- Don't waste water. "If you're using a sprinkler system for your new lawn, make sure you're not watering the sidewalk or pavement," he said. "If you have an irrigation system, be sure your irrigation heads are pointed toward your plant material."
-- Mulch judiciously. "An inch of mulch holds moisture in, but too much mulch creates a problem: Water can't get through the mulch to moisturize your soil," Sellmer said. Too much mulch also encourages root growth into the mulch layer.
-- Delay the fall application of fertilizer. "You need water for fertilizer to be available to the plant," he said. "I would be less inclined to fertilize plants and shrubs now because there's no moisture to move the fertilizer -- especially in a dormant lawn. My hope is that we'll get a break in the drought and get more rain in the next few weeks. Then you can look at a late-fall fertilization plan. But to fertilize now is not a positive."
-- Water later in the day. Sellmer said plants recover from the heat, wind and light of the day during the late hours in preparation for the next day. Evening watering assures that moisture stays on the ground and doesn't evaporate under direct sunlight and heat.
"Evening watering makes sure water is there for the plant to take up," he said. "The best irrigation goes to the ground and not over the tops of plants. Plant leaves should have a chance to dry before nightfall to reduce the chances of fungus or mildew diseases. We're in the downward swing of plant growth, so leaf diseases are less of an issue at this time of year."
-- Don't give up on the season. Even with a few concessions to a hot, dry summer, this fall still is a good time to plant trees and shrubs in the region, according to Sellmer. "It's absolutely a good time to plant, but you must also water deeply every few days until winter comes -- especially if it stays dry," he said.
"Temperatures are cool but the ground is warm, and roots will grow until the ground freezes in late fall or early winter, so they need a water supply going into winter. This gives the plant a jump start on establishing prior to winter, and helps it to take off faster in the spring. Track rainfall and supplement with deep watering over the top of the root ball every few days."
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Last Updated November 18, 2010