URBANA -- Gardeners were really glad to see the cooler weather and some rainfall at the end of the 2012 gardening season. The question is whether 2013 will be any better, said a University of Illinois Extension horticulture educator.
“For a lot of areas in Illinois, the usual fall rain did not materialize, and through mid-January snow has been scarce,” said Richard Hentschel. In a more normal year, plants start the season by using the soil moisture available from the melted snow and spring rains. Later those plants will rely on the soil moisture farther down in the soil profile. This is why, after a landscape plant is established, gardeners tend not to worry about watering.
“As we approach spring, not only is the deep soil moisture lacking, but any upper soil profile moisture available will be quickly used unless there is adequate rainfall,” he explained. “If this weather pattern continues, it will mean another gardening season requiring lots of water and close attention to the condition of all landscape plants.”
Hentschel said that gardeners can do some things out in the yard that benefit the landscape even if snow and rain from late winter through spring is not adequate.
“If you have a compost bin or pile, adding organic matter does more than just feeding your plants,” he said. “Garden soil that contains 1 percent organic matter holds one-third of a gallon of plant-available water per cubic foot. Soil that contains 3 percent organic matter will provide one gallon of available water.”
Compost can be incorporated easily into a bed of flowers or vegetables either in the fall or early spring before planting. In perennial beds, it is best to add compost between plants and let it decompose, working itself into the soil profile. On more permanent landscape plantings, the compost can be applied as if it were a mulch layer, much like using bark mulch. Like the bark mulches, the compost will break down and find its way into the soil profile.
The third advantage that compost provides is the beneficial change in soil structure. This change allows root systems to grow deeper into the soil, finding more soil moisture as they do. “When you combine the availability of nutrients, the water-holding capacity of organic matter, and the change in soil structure, it is easy to see how this will help plants, drought or not,” he said.
Plant selection will also be an important part of redoing a planting or bed that lost plants due to the drought, disease, or insects.
“If there is a location that has historically been dry in your landscape, plants that have a strong drought tolerance will perform much better than a high-water-use plant,” he said. “Dry sites typically have a western or southern exposure or are those parts of the yard that are on a slope or in soils having a high percentage of sand. Sand is just a very small rock that does not have any nutrient- or water-holding capacity and promotes very rapid drainage after a rain.”
Many local native plants have root systems that can take advantage of soil moisture several feet into the soil profile. Lawn grasses have roots that go down 8 to 10 inches in good soil; native grasses will have roots 6 feet or more into the soil.
“How we water will likely be different in 2013,” Hentschel said. “Watering restrictions are almost certain and are, for many gardeners, something that has been in place already for a number of years. By respecting those restrictions, a ban on watering altogether can be avoided or at least postponed.”
Water properly so as not to waste water, and place it to the best advantage of the plants. Watering at the base of a plant or using a drip hose rather than using a sprinkler prevents water loss into the air or off-target areas. Allowing the water time to soak in deeply will encourage plants to send roots deeper into the soil, making them more drought-tolerant. This may mean watering once, letting it soak in, and coming back a second time to thoroughly moisten the soil.
If watering is restricted to even or odd days, it is not necessary to water on the appointed day if the soil is moist enough, he added. Frequent shallow watering will not promote a good root system for the plants.
“Always water deeply when you do water and then wait until the soil begins to dry out before watering again,” he said. “Do not use the plants as an indicator and wait until you see them wilting.”