Drought over, but homeowners should still keep an eye on water needs for vulnerable plants, trees

Recent rainfall moved northern Illinois from a “moderate drought” to just “abnormally dry,” per the federal government’s drought.gov drought monitor.

But you may still want to keep an eye on vulnerable trees, bushes and other plants, according to an expert from the Chicago Botanic Garden.

“This is a really great rain because it’s slow,” said Tim Johnson, senior director of horticulture at the Glencoe park, during an interview on Wednesday.

“This is exactly what we need.”

According to National Weather Service meteorologist Kevin Doom, Wednesday’s rainfall ranged from a bit more than a half-inch in the northern suburbs to 1.5 to 2 inches south of I-80.

Johnson was surprised to hear the federal government thought the suburbs were in a drought, instead describing things as “more of a bit dry.”

He said the gardens did some supplemental watering last month. But at his home in Highland Park, he hasn’t seen any signs of stress in his trees or plants.

Pay attention

Johnson said more attention must be paid to the water needs of newer trees and shrubs to help them become well established.

He suggests weekly watering the first year after they are planted. He planted a serviceberry tree, an arbor vitae and a buttonbush this year and has watered them.

How long and how much may depend on whether the tree was sold in a container or if it was balled and wrapped in burlap. Nurseries often use a lighter soil mix, which dries out more quickly, in containers, he said. That may require more water for four to six weeks than a balled-and-burlapped transplant.

For older trees and plants, “My philosophy at home is I try not to water at all. I wait until I see signs of stress,” he said.

Watch for signs

Wilting of leaves is often the first sign that something is suffering, he said, or you may notice off-green color developing.

Evergreens, such as yews, may start shedding their internal leaves. But evergreens can also go off-color due to too much water, he said.

“It (the tree or plant) is going to be telling you it is unhappy,” he said. “Plants give warnings.”

Johnson suggests using a soil probe to pull a plug of soil for examination or digging in with a trowel.

You should also know what kind of soil the plant or tree is in. Is it heavy clay? Is it sandy? Both affect water retention.

“It’s getting to know your garden,” he said.

If you do water a tree, consider using a plastic slow-release watering bag around the tree. Or let a hose trickle at the base.

In an extended dry period, Johnson worries about his big oak trees and waters them.

His lawn, however, can go brown. “I let the grass go dormant. For me, I don’t mind it … because then I don’t have to mow it,” he said.

Meanwhile, Doom said there are some signals the area may see above-average rainfall over the next few weeks.