8 Simple Summer Tree Care Tips Every Homeowner Should Know to Prevent Damage

It's easy to bypass caring for trees when perennials, veggies, and rapidly growing weeds demand attention during the height of summer. But just like all other plants, these stately landscape workhorses can suffer from stress due to heat and drought. Most summer tree care tasks are easy to accomplish with standard gardening tools and basic skills. Call a professional arborist for jobs that are beyond your reach, but otherwise, here are 8 easy tips to keep your trees healthy and strong during the summer.

1. Don’t Plant Trees in Summer

Summer heat, dry spells, and drought make it challenging for a tree to get established. Spring or fall, when temperatures are cooler and there is more regular rainfall, make these seasons the best times to plant a tree.

If you cannot avoid planting in summer, spread a 2- to 3-inch-thick layer of mulch around the root zone of your new tree. If there is no substantial rainfall, check the soil moisture every other day and water enough to keep the soil evenly moist at all times.

2. Assess Your Trees' Storm Fitness

Summer storms with strong winds and heavy rains create additional seasonal needs for trees of all sizes. Make sure your trees are ready. Stake young trees to prevent them from swaying back and forth as their root systems are still weak, and the movement may damage the roots or uproot the tree. Inspect mature trees with heavy or unbalanced limbs, which should be pruned or supported by cabling or bracing (a service provided by arborists).

3. Prune for Health and Structure

While winter is the prime time for pruning most trees, keep your cutting tools handy for these essential summer pruning tasks:

• Cut dead, crossing, or rubbing branches back to a main branch or the trunk.
• If branches have been broken in a storm, prune them as soon as possible, as they may create a hazard.
• Remove any water sprouts—boldly upright growing green stems rising from interior branches. Water sprouts are excess growth that shades interior branches and weakens the overall structure of the tree.
• Prune off suckers. These fast-growing stems rise from the roots at the base of the tree or the lower portion of the trunk. Suckers are not structural and simply rob the tree of valuable nutrients. In fruit trees, neither suckers nor water sprouts produce fruit.

All of the above also applies to fruit trees. While the bulk of fruit tree pruning happens in winter, summer is a great time to assess the light penetration into the center of a fruit tree and overall branching structure. Maintaining an open canopy encourages good fruit development and air circulation.

4. Know Which Trees Should Not Be Pruned

Some trees should not be pruned in the summer. Oaks and elms are especially prone to disease when pruned in summer. The pathogens that cause oak wilt and Dutch elm disease are active and will quickly invade an open pruning wound during warm weather. Wait until late fall or winter to prune oaks and elms.

5. Water Newly Planted Trees

For the first one to two years after planting, it is key to water young trees diligently so they form deep roots. Check the soil moisture of a new tree regularly. The soil around the roots should be moist but not soggy. Water new trees with a hose fitted with a sprinkler head, a soaker hose, or a spot sprinkler. The goal is to deeply moisten the entire root zone and slightly beyond to encourage rooting into nearby soil.

Most established trees—those that have been in the landscape for more than two years—only need watering during periods of drought. Soak the entire area under the tree’s canopy to a depth of about 8 inches to ensure the extensive root zone receives adequate moisture. Water established trees deeply and infrequently. Irrigate every three weeks during drought periods.

6. Spread Mulch

Young trees benefit from a 2- to 3-inch layer of organic mulch (not rock or rubber mulch) over their root zone. Mulch helps conserve soil moisture while suppressing weeds and enriching the soil. Use shredded bark mulch, pine needles, and cocoa hulls. There’s no need for landscape fabric under the mulch. Be sure to maintain a 3-inch-wide mulch-free circle around the trunk of the tree to prevent fungal diseases.

7. Scout for Pests and Diseases

There’s a helpful adage when it comes to caring for plants: the best fertilizer is a gardener’s shadow. This applies to trees, too. The diseases affecting ornamental trees vary greatly, but keeping an eye out for unhealthy-looking foliage and bark is a good start. A few marred leaves or a short stretch of damaged bark is worth monitoring. If the distressed area grows, search for causes and remedies to diagnose the disease. Anthracnose, blight, and cankers are common in deciduous trees, and needle cast and other diseases are found in evergreens.

The same early detection applies to pests such as aphids, bark beetles, and scale insects. In most cases, a minor infestation won't cause permanent harm, but if pests start to overwhelm your tree, you'll need to take action.

8. Don't Apply Fertilizer on Dry Soil

Especially in urban settings where the soil is not naturally replenished with leaf litter and other organic matter, trees need fertilization. Apply a slow-release granular fertilizer in early summer, which provides the tree with enough nutrients throughout the season. Spread the fertilizer evenly around the drip line of the tree without letting it touch the trunk. However, never apply fertilizer on dry soil; water your tree before fertilizing.