With concerns about drought conditions deepening across Texas, arborists and cities alike are urging residents to water their trees before they show signs of stress. However, many residents are unaccustomed to watering trees, whether they’re mature or newly planted, said Rachel McGregor, the urban forestry manager for the Texas Trees Foundation.
While watering tips differ by species, McGregor offered her best practices for working with Texas trees that have withstood years of extreme weather, including the 2021 winter storm and prolonged heat waves.
“The majority of healthy trees will not have any devastating, lasting effects from a drought because they were a healthy tree,” McGregor said. “But we’ve had the freezes that have already caused forest health issues and stressed the trees out, and now when you have drought issues as well, that’s when you start seeing a lot of trees failing.”
How should you start watering your trees?
Trees should be prioritized over other landscape plants, including grass, because trees have a more difficult time recovering from loss of water. The Texas Trees Foundation advises watering outward from the dripline, or the edge of the tree’s branches, rather than focusing on the tree’s trunk.
While sprinkler systems are effective for watering lawns, other products typically are better for the kind of slow, deep watering that trees require, McGregor said. Residents should use a bubbler, multiple drip emitter or soaker hose to deliver water to the root zone. Established, mature trees require, at most, watering twice a week, while newly planted or younger trees likely will require more frequency depending on species, she said.
The simplest way to irrigate trees on your property, according to McGregor, is to leave your hose on a slow trickle and place it in different locations around the dripline. McGregor has a simple tip for knowing when to move the hose to the next spot.
“Once you get a longer screwdriver through the soil profile (of 12 inches) easily, then you can turn off the water,” she said. “Answering questions on how much to water a tree is hard, because soil types are different, tree species are different. You don’t know the area that the tree is in. So really using the screwdriver test is the best method for proper watering.”
Residents may be surprised by the amount of time they must leave their hoses on to deeply water their trees, McGregor said. The minimum time could be multiple hours in each root zone, depending on how water-deprived the soil is.
“Watering for your lawn is very short, 15 to 30 minutes, but that’s because the roots on the turf grass are very short within the soil,” she said. “With tree roots, you’re trying to get 12 inches of water through that soil.”
Do’s and don’ts for not breaking the bank (or your trees)
The foundation’s general advice is to water sometime between 7 p.m. or 8 a.m. while still following local watering schedules and restrictions. Turning on your hoses or sprinkler system during the hottest part of the day means that more water will get lost to evaporation, leading to higher water use and a more expensive bill at the end of the month.
Spreading mulch near the tree’s roots — not the area near the tree’s trunk — also can help minimize evaporation of soil moisture and limit the amount of rainwater runoff during storms. Using wood chips or shredded bark will help residents prevent weed competition and conserve water as well.
At the same time, McGregor warns against using fertilizer or pruning during summer months. During dry conditions, trees are trying to maintain their current size and cannot sustain growth that would be induced by the fertilizer, she said.
“You want to avoid fertilizers, especially during the heat of the summer because you can burn your tree up,” McGregor said. “You don’t want to feed the tree at this point in time because it is, again, just trying to maintain what it has.”
If residents start noticing issues with their trees — including wilting or discolored leaves — they can also consult with a certified arborist about the best course of action to maintain the tree through the summer.
Why is it important to water your trees?
McGregor understands that the extra expense of regular tree maintenance won’t be a welcome one to Texans this summer.
But the benefits that trees offer, including cooling the air near homes and reducing the urban heat island effect, outweigh the costs incurred over the summer, she said.
Arborists are not expecting residents to continue watering in other months of the year when rainfall is more plentiful, McGregor said.
“I’ll hear people say: ‘Well, they’ve survived out here for this long and I haven’t had to do anything.’ Well, the problem is our summers are longer and hotter, and there’s less water, and it’s year after year,” McGregor said. “It may be an expensive water bill, but this tree is giving you so many more benefits over the long run than a few high water bills during the summer.”
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