‘Drought definitely can kill a tree or shrub’: How to keep your trees healthy during ongoing drought

From Philly and the Pa. suburbs to South Jersey and Delaware, what would you like WHYY News to cover? Let us know!

We’re used to seeing trees dropping their leaves in the fall — but according to Pennsylvania arborist Jason Parker, district manager at the Davey Tree Expert Company’s Warminster office, it could also be a sign of something more ominous: failing health due to the region’s record-breaking dry spell.

“Drought definitely can kill a tree or shrub,” Parker said. “So don’t ignore this and just think that it’s regular fall color change [and] leaf drop. It’s definitely more than that.”

Unfortunately, he says, the negative effects of the region’s ongoing drought conditions might not become noticeable until the spring.

“And if you wait till the spring, then it might be too late, depending on the health and condition of the tree,” Parker said. “You might have some bigger issues that you’re dealing with at that point.”

Ornamental trees, like dogwoods and Japanese maples, along with evergreen trees are the most vulnerable to dry conditions, while larger “shade trees,” like maples and oaks, tend to be hardier. Delayed consequences can include smaller, off-colored leaves, or, in the case of evergreens, a premature dropping of needles.

However, there are several steps tree owners can take to ward off drought-related harm.

Tip #1: Give your tree deep and regular waterings

Parker advises watering on at least a weekly basis by setting your hose to a trickle, and allowing it to soak into the soil for about an hour, give or take, depending on the tree’s size.

“You want to promote that deep watering that gets the water down into where a lot of those fibrous roots are,” Parker said. “If you’re just watering on the surface, a lot of times that will evaporate if temperatures get too high.”

Don’t worry about overwatering, he added

“In conditions like this, you almost can’t do it enough,” he said. “There are very few trees that you’re going to overwater.”

Tip #2: Mulch, mulch, mulch

Even when trees are deeply watered, they can still lose moisture due to evaporation — which is why Parker also suggests mulching.

“So you want to make sure that you’re not putting too much mulch against the base of the tree and around the trunks, but enough to help retain some moisture and keep that root zone a little bit cooler,” he said.

Mulch can also prevent weeds from taking root around the tree, creating competition for water.

Mulching is especially important in the city, where trees often don’t have much protecting the soil around their roots.

“When we plant a tree in an urban environment, we’re taking it out of the forest where it’s got other trees for protection,” Parker said. “The leaves fall, they create kind of this natural mulch. All of that is typically stuff that we don’t do. We’re planting grass all the way up under these trees. And there’s a lot of competition. You’ve got a lot of reflected heat from buildings and other surfaces like roadways. Things like that all add a lot of stress.”

Tip #3: Call in the experts

If you’re worried about the health of your tree, and think it might need more than a bit of water and mulch, Parker advises calling in the experts — certified arborists — to assess the tree’s health and make a plan for care.

Among the steps they can take is soil care.

“We always build any of our plant health care programs starting with soil care,” Parker said. “We want to make sure that we’re offering the nutrients that the tree needs. And we put some additives in there that help with things like drought tolerance, moisture retention, things like that, so that you’re getting all of the nutrients that the tree needs.”

Having said that, you may want to avoid attempting to DIY your soil care, as fertilizer can pull water from the roots and put additional stress on the tree.