Summer Tree Care: Tips From the Nursery

When we think of trees and summer, we don’t always think of tree stress. Instead, we tend to think of lush canopies providing shade, but out West, summer can be intense. We’re not talking about a heat wave or just a few hot days; we’re talking about months of sun, dry air, wind, drought-like conditions, pests, and urban heat islands or reflected heat from rocky landscapes.

Whether you’re an urban forester, a property manager, or a homeowner trying to keep trees safe through summer, tree care can make a big difference. Both newly planted and established trees have specific summer care needs, and before the heat really kicks in, we want to make sure you’re keeping your trees thriving!

Quick Links:

• Why Summer Tree Care Matters in the West
• Why Healthy Roots Matter Most in Summer
• Watering Trees Properly During Summer
• Mulch Matters More Than People Think
• Heat Stress & Sunscald in Trees
• Summer Tree Pests to Watch For
• Spotting Summer Tree Stress
• Tree Care Mistakes to Avoid in Summer

Why Summer Tree Care Matters in the West

While summer tree care is important everywhere, out West, trees face a unique combination of region-specific environmental stressors. In Utah, Colorado, Oregon, Idaho, and across the West, summer brings intense sun (aided by elevation in some areas), dry air, hot winds, and sometimes long stretches of limited to no rainfall. When paired with urban stressors like compacted soils and heat islands, every tree, young, old, newly planted, or well-established, can struggle with heat and drought over the summer months.

In summer, these stressors can make trees more vulnerable to tree pests and tree diseases. Aphids, spider mites, borers, and other problems tend to show up when trees are already weakened by environmental pressures like heat and limited nutrients or water.

Providing appropriate seasonal support can help trees stay resilient against seasonal stressors. In summer, that means watering, mulching, pest monitoring, and, when necessary, early intervention to help trees cope with hot, dry conditions in the West.

Why Healthy Roots Matter Most in Summer

One of the places where these stressors have the biggest impact is, unfortunately, some places we can’t monitor as easily. While summer stress is easy to see in the canopy, the real issues typically start below ground. Healthy roots are essential to tree care, and caring for them is even more essential in hot, dry Western summers.

Because of low humidity, high winds, intense sun, and limited rainfall, Western soils can dry out quickly. In urban areas, shallow, compacted, and rocky soils, especially those surrounded by pavement, can make it difficult for roots to reach or receive water, especially if supplemental watering is limited. When roots struggle to meet basic needs, the whole tree suffers, making it more vulnerable to stressors we see in the canopy, such as leaf scorch, pests, and diseases.

For young and newly planted trees, root support is especially important. While young trees may look okay above ground, what’s happening below ground is still fragile. Roots are still developing, and consistent deep watering and mulching over its first few summers can help protect it from heat stress and, ultimately, make the difference between a tree that simply survives and one that thrives.

Even a tree that starts with healthy roots, like trees grown in an air pot, needs support. Ensuring healthy roots during establishment can build resilience, and if you’re seeing issues above ground, consider what’s happening below ground first.

Watering Trees Properly During Summer

Step one for summer tree care is proper watering. It may seem simple, but watering is one of the things most people get wrong. First, assuming rainfall will meet water needs is a big mistake in the West, or any region.

Trees need water that reaches the root zone, and that means deep watering rather than surface watering. Deep roots make stronger trees, and shallow watering encourages shallow roots. Deep watering means trees are better equipped to handle western stressors such as heat, wind, and drought.

Ultimately, you want to water so that the moisture soaks into the soil rather than running off onto the lawn, pavement, or street. Translation: that means slower watering! This is especially true for newly planted or young trees that have smaller root systems and are really working to develop them in the first few years.

A few summer watering tips to help you and your trees:

• Watering deeply is more important than frequency. Deep, slow watering once or twice a week helps ensure water reaches the root zone where it’s needed. For newly planted trees, deeper water 2-3 days a week if it’s hot.
• Focus on the soil, not the trunk. Going for the root flare is natural, but the roots extend well beyond that, and watering should focus on the area under the canopy, not just the base of the tree.
• Slow watering is best. Whether you opt for a drip line, soaker hose, slow-running hose, or tree watering bag, water slowly so water has time to penetrate and be absorbed. For our retail nursery customers in Riverton, Utah, ask about our tree watering buckets!
• Check the soil before watering. Ideally, soil should have the chance to dry before you water again. If roots stay consistently wet, you open the door to fungal growth and disease. Several inches below the surface, soil should be moist, but not wet.
• Water early when possible. Watering in the morning gives the trees time to absorb water before it evaporates during the hottest part of the day.
• Make adjustments for weather and soil. Whether it’s extra hot or windy for a stretch, or the soil is rocky and sandy, you may need to water more frequently. On the other hand, soils with a high clay content may be harder to penetrate, so slow watering will prevent runoff. Pay attention to the elements and your specific soil to make the best watering decisions.
• Lawn sprinklers are not enough. Lawns don’t have deep roots, so shallow watering is often enough for them. Lawn sprinklers will not provide the depth of watering that trees need, especially during a hot summer.
• Newly planted trees need more attention. The first few growing seasons are essential for root establishment. Even if you start with healthy rootstock, young trees still need care during establishment, including supplemental watering.
• Watch for stress. Curling leaves, wilting, leaf scorch or drop, and browning can all signal that a tree is struggling. Keep an eye on your trees and regularly monitor their watering needs, especially for new and young trees.
  

Proper watering doesn’t mean daily watering. Instead, it means mindful watering. Slow, deep watering will support strong roots, consistent soil moisture, and, in the long term, more resilient, healthier trees.

Looking for drought-tolerant Colorado Trees or drought-tolerant Utah Trees?

Mulch Matters More Than People Think

Some people tend to see mulch as decorative, or giving beds and trees a cleaner, more polished appearance, but it’s really doing way more than that, especially in hot, dry landscapes. In fact, a properly placed mulch ring stabilizes soil temperatures, helps maintain moisture, and improves soil conditions as it breaks down over time.

Mulch is particularly helpful in the summer, as it can keep soil cool and extend moisture retention after watering. To get those benefits, though, you must mulch properly:

• Apply 2-3 inches of mulch around a tree, extending over the root zone.
• Keep mulch away from the trunk to avoid trapping moisture and encouraging fungal growth.
• Avoid what’s referred to as a “mulch volcano,” where mulch is piled high around the trunk.
  

If you think about mulch as a light blanket for the soil and roots rather than a turtleneck for the tree, you’re on the right track!

Heat Stress & Sunscald in Trees

If you’ve ever had a sunburn, you know how relentless summer sun can be. Trees feel that too. And as you can get sunburn, trees can get sun damage too, with the impact ranging from mild to severe, just like sunburns. Trees can get burned too, especially out West, where the heat is compounded by dry air, wind, and heat-radiating rocky landscapes or, in urban areas, pavement.

When we’re out in the sun too long, our skin burns, we get tired, and dehydrated. Again, trees are the same, and heat stress may show up as curling, wilting, or dropped leaves. Sunscald on trees, however, shows up on the bark, which might look damaged, cracked, or even sunken. This usually happens on the S/SW side of trees where sun exposure is often the most extreme. As one can imagine, young trees with thin bark are most vulnerable.

To help trees manage heat stress and sunscald, ensure you’re watering and mulching, but avoid pruning or pushing any new growth (no fertilizer). These will reduce stress on the trees. For young and newly planted trees, some trunk protection may be necessary. 

In cases where damage is severe or worsening, or where there’s also canopy decline, you’ll want to contact a certified arborist to come look at the tree and determine if it’s time for tree removal.

Summer Tree Pests to Watch For

One concern with a stressed tree is that it becomes more vulnerable to other problems, such as tree pests. A healthy tree can often tolerate moderate pest activity, but one that’s already stressed? They often don’t fare as well.

Common summer pests include:

• Sap-feeding pests- Aphids, spidermites, and scale insects all feed on leaf sap and, over time, can weaken a tree, especially one already struggling. Look for aphid clusters, stippled or discolored leaves, or bumps on bark and twigs.
• Wood Boring Beetles- These pests are sometimes opportunists, looking for vulnerable or distressed trees to attack. Serious infestations can lead to tree removal, so keep an eye out for small holes, “sawdust,” sap, bark damage, or branch dieback.
• Leaf-feeding pests- Caterpillars, leaf rollers, and other leaf feeders can intensify the impacts of heat stress. Look for skeletonized leaves, defoliation, or considerable canopy decline.

While not every tree pest is an emergency, and not every infestation can take a tree down, when trees are already struggling, pest damage can make things much worse. You’ll want to carefully monitor the tree(s), the pests, and overall tree health. If you’re concerned or can’t identify the pest, call an arborist!

Spotting Summer Tree Stress

We’ve touched on a few of the more common symptoms of tree stress, but catching it early gives you the best chance of reducing tree stress.

Keep an eye out for:

• Drooping or wilting leaves
• Leaves that are curled up, dry, or brittle
• Leaves with crispy tips, brown edges (leaf scorch)
• Leaves that drop and leave a thin canopy
• Dying branches
• Cracked, sunken, or damaged bark
• Soil that is dry or pulling away from the root ball.

Tree Care Mistakes to Avoid in Summer

Of course, one of the best ways to take care of trees in the summer is by making sure they head into the season healthy. And, when you see a tree struggling in summer, quick fixes can often create more stress, so best to avoid those mistakes too!

A few summer tree care mistakes we see often:

• Shallow watering: Frequent, but shallow watering or relying on lawn sprinklers isn’t going to meet a tree’s water needs in summer. Water needs to reach the deeper root zone.
• Overwatering: When a tree looks dry, the instinct is to water it frequently, but soggy soil can restrict oxygen around the roots and actually create even more stress.
• Mulch volcanoes: It’s tempting to protect the roots from sun and heat, but mulch piled against the trunk traps moisture and can create problems of its own.
• Fertilizing: You might think you’re feeding a hungry tree and that will help it regain strength, but the truth is, it’s not the cure for heat stress. Additionally, it may force the tree to focus on new growth in the canopy rather than building its root system.
• Pruning: Fewer branches will ease stress, right? Actually, it might expose more of the tree to the sun, increasing the risk of further heat stress. Also, over-pruning can be similarly stressful. Dormant season pruning is better for trees.
• Assuming all brown leaves are equal: Multiple problems can look the same. There are several tree issues that manifest on the leaves, from leaf scorch and drought stress to tree diseases and pests. Check the trees and the soil and monitor.
• Neglected newly planted or young trees: These trees need a little more TLC their first few seasons while roots are establishing, so keep a close eye on them.
  

If your trees are looking stressed, start with the basics: check the soil, check the mulch, look at the leaves and trunk, and consider what other stressors the tree might be exposed to (heat islands, compacted soils).

If you’re struggling to identify the problem, contact a certified arborist near you. Not only can they help you appropriately diagnose the problem, but they’ll also be able to help you implement the right support.

For property managers and municipalities, hiring tree services over the summer to provide supplemental watering is a good start, as it starts with strong, healthy stock. SuperTrees can help with both.

With thousands of trees and hundreds of native varieties and cultivars, we can help you start with the trees that are right for your community, from drought-tolerant to fast-growing. We’re ready to help you see your urban forest or managed landscape thrive, so reach out to our team today!