Standard lawn sprinklers are great for turf, but they rarely deliver enough moisture to keep established trees healthy during an Idaho summer.
Surface-level watering wets only the top few inches of soil, leaving most of a tree's root system thirsty and vulnerable to extreme heat.
In Eastern Idaho's high-desert climate, deep root watering is essential for building a resilient canopy that can withstand drought, alkaline soils, and destructive summer pests.
Can deep root watering help trees survive drought? Yes. Deep root watering delivers water straight down to your tree’s roots, where it really needs it.
It keeps surrounding grass from stealing the moisture, reduces water evaporation from the sun, and encourages your tree’s roots to grow deep into the ground instead of staying near the drier surface.
“It’s a wonderful topic to discuss as we experience yet another year of extreme temperatures and drought conditions here in Idaho,” says R.J. King, fertilization division manager at Village Gardener in Jackson Hole, WY, a partner company with Lawn Buddies.
Lawn Buddies doesn’t offer deep root watering for trees as part of its services, but it’s a great homeowner habit to supplement other Lawn Buddies plant health care services like deep root fertilization, systemic tree injections and pest control.
Let’s learn more about how to water trees in summer.
Trees rely on their roots to absorb water and nutrients. Unlike the shallow-rooted flowers and plants in your garden, tree roots stretch deep into the ground.
Meanwhile, the irrigation your trees typically get is pretty surface-level. Regular watering usually only moistens the top layer of soil, which means tree roots can still be craving water. Deep root watering ensures that water reaches those deep roots that absorb water and nutrients.
Put your feet up. There are quite a few:
Deep root watering promotes deeper root growth, where the soil retains moisture longer. When you consistently deliver water to deeper soil layers, tree roots grow deeper to reach that moisture.
Trees with deep roots are better equipped to survive extended dry spells, resist strong winds, and access nutrients that lie far below the surface.
As summer turns to fall, we turn off our irrigation systems to prepare for winter and prevent freezing.
But your trees are still thirsty.
Even after leaves have fallen, your trees’ roots remain active. This is the time when roots absorb moisture and store nutrients for the winter months, preparing the tree for spring growth.
Trees and shrubs need their roots well watered before heading into winter dormancy, King says.
Fertilizer gives your Idaho trees and shrubs a nutrient boost that improves their health and appearance, from strong roots to glossy leaves to plentiful, pretty flowers.
When you fertilize your trees and shrubs, that fertilizer needs to make its way down to their roots, deep beneath the soil. Deep root watering helps.
“Those nutrients need water to push them deep into the root zone and help the tree uptake them efficiently,” King says. “If enough water hasn’t penetrated the soil, the tree will be unable to use the nutrients efficiently, causing extra stress on your trees and shrubs.”
Our soil here in Idaho is often heavily compacted and has a high pH level, King says.
That means beneficial fertilizer gets locked up in the soil and doesn’t always reach your tree’s roots.
Deep root watering for trees naturally aerates the soil as the water flows through, King says. The looser soil, plus the extra water, helps the fertilizer work more effectively.
“Deeply hydrated roots protect trees from summer heat waves that often bring destructive pests,” King says.
Those pests take advantage of an already drought-stressed landscape, he says, from lawns to trees and shrubs.
Hydrated tree roots also help defend against winter dessication, King says, which is water loss through leaves and needles that leads to damaging winter burn.
“That helps ensure a stronger and healthier emergence in the spring,” he says.
By concentrating water directly where it’s needed, deep root watering is considerably more efficient than traditional irrigation methods.
If you have a large-scale commercial property with lots of trees, it can really reduce water waste.
Deep root watering delivers moisture to the tree's root zone, usually 12 to 18 inches below the surface. The most effective way to do this is with a soaker hose, drip irrigation system, or a specialized deep root watering tool.
In addition to going deep into the ground, the water should also go slowly. A slow, steady flow ensures the water soaks the soil and roots thoroughly and doesn’t evaporate.
While professionals use a deep root spike to deliver water and professional-grade pumps, homeowners can do Idaho deep root watering for trees with simpler tools.
King suggests using a soaker hose wrapped in a circle around the tree, or a sprinkler set to spray only a few inches high. Keep the soaker hose 2-3 feet away from the trunk.
“If it’s too close to the trunk, it can cause fungal issues and root rot,” he says. Avoid getting any tree leaves or needles wet, too, he says.
“A general rule of thumb is a slow, deep watering down to 8 to 12 inches in the soil,” King says. “Slowly water the trees and shrubs starting at the outermost tips of the branches.”
This is also called the “drip line,” he says, the perimeter directly underneath a tree’s canopy where water naturally drips from leaves. This is where most of your tree’s feeder roots are located, so it’s the best area for deep watering.
“It’s where nature drops its water,” King says, “and we try to mimic that.”
Once or twice a month for established trees in spring, King says, and once a week during the heat of July and August.
“Back off in fall to one or maybe two times per month,” he says, “as trees and shrubs prepare for lower temperatures and eventual dormancy. We don't want to risk freezing those fine roots.”
How do you know when your tree has had enough water?
“You can use a long screwdriver or metal spike to test the depth of your watering,” King says, or purchase a soil probe.
“All of these tools will move more easily in moister soils and become difficult when you start to hit the dry soil.”
In addition to deep root watering, add organic materials to the soil like hay, manure, wood chips or leaves to help your tree’s soil retain the moisture, King suggests.
A layer of bark mulch helps retain moisture, too, he says, but not too close to the trunk. Keep the mulch 3-6 inches away from the trunk.
Avoid the dreaded “mulch volcano,” King says. That’s when mulch is arranged in a pile around the base of the tree. It traps moisture against the bark, causes rot, suffocates roots, and can eventually kill the tree.
“Mulch should be arranged like a bagel or donut, “ he says, “not a volcano.”
Q: Can deep root watering help trees survive drought?
A: Yes! Surface watering often evaporates quickly, especially during hot summer months, causing drought stress in trees. Deep root watering delivers consistent moisture deep in the soil, where it lingers longer and helps prevent damage like wilting or browning foliage.
Q: What’s the best time for deep root watering?
A: Like all plant watering, morning is a great time for deep root watering trees. It lets more water stay in the soil instead of evaporating. Morning watering also gives your trees a good drink before the heat of the day.
Q: How much water do trees need during deep root watering?
A: The general rule is to provide about 10 gallons of water per inch of the tree trunk’s diameter. So a tree with a 5-inch diameter trunk would need 50 gallons of water delivered slowly and steadily.
Q: Do flowers need deep root watering, too?
A: No. Save the deep root watering for trees and shrubs. Flowers have shallower roots that don’t grow deep underground, so they absorb plenty of water through routine irrigation.
Proper watering is just one part of Idaho Falls tree health care.
How to water trees in summer? Your trees will appreciate deep root watering to strengthen their root systems.
Proper watering, fertilization and proactive plant health care all work together to improve a tree's ability to tolerate heat, pests, and environmental stress.
At Lawn Buddies, we’re tree experts. We provide professional plant health care in Idaho Falls as an add-on to our lawn care program.
That means we have the skills, knowledge, and services to keep your trees healthy and thriving, plus tools like deep-root fertilization and systemic tree injections to treat health threats.
Expert plant health care is available to our customers who use our full-service lawn care program.
Choose an Idaho Falls professional lawn care service that makes it easy, bundling your yard’s most-needed treatments into one convenient, no-fuss plan.
Got a few minutes? That’s all you need to get started. Just fill out the form on this page, call us at (208) 656-9131 or read more about our services. Then you can kick back and relax in your healthy, thriving yard.