July generally signifies the start of intense heat and infrequent rains. That means lawns and gardens are often in need of water.
Whenever the weather doesn’t provide enough rain, supplemental irrigation will be needed for landscapes, especially vegetables, bedding plants and newly planted trees and shrubs, says LSU AgCenter horticulturist Allen Owings.
Of the tremendous amounts of water applied to our landscapes, much is never absorbed and used by the plants. Some water is lost to runoff by being applied too rapidly; some evaporates from exposed, unmulched soil.
“The greatest waste of water is applying too much too often,” Owings says.
It is best to irrigate at a rate so the soil can take in the water being applied, Owings says. You don’t want irrigation water to go into the parking area or down the street. Water a couple times weekly instead of watering a little bit every day.
Allowing the soil to dry out somewhat between waterings encourages root development at greater depths where soil moisture is highest. Plants watered frequently but lightly are more apt to develop roots close to the surface, making them more vulnerable to wilting.
Watering at the right time of day is important, Owings says. It is best to irrigate when the sun is low, the winds are calm and temperatures are cool. This will save water as much as 30 percent by reducing evaporative losses.
The best time to water is from early morning, a couple of hours before sunrise, until midmorning. Most landscape and lawn areas need ¾-1 inch of water weekly.
Plants in containers will likely need to be watered every day, says AgCenter horticulturist Dan Gill. Smaller pots or pots in the sun will dry out more quickly, and containers made of terra cotta don’t retain moisture as well as plastic pots.
Mulch well around landscape plants, Owings says. Use 2-4 inches of mulch around trees and shrubs. This reduces evaporation, moderates soil temperatures, improves water penetration and helps control weeds that compete for water. Pine straw is the best mulch in Louisiana.
Maintaining your landscape by mowing, weeding and pruning will create an environment that requires less water.
“Irrigation will continue to be important as we move through the rest of the summer and fall in Louisiana,” Owings says.
Got a gardening question? Write to GardenNews@agcenter.lsu.edu.