How to Keep Your Plants Healthy in the Heat of Summer

Summer heat can be brutal on a landscape. Long stretches without rain, high temperatures, and intense sun can quickly turn a thriving garden into a struggling one, and once certain trees and shrubs start to decline, there is often no bringing them back. The good news is that keeping your landscape healthy through the hottest months does not require a complicated routine. According to JR Hodder, a landscape designer with Johnson’s Landscaping Service, Inc., with 20 years of design experience and a Master’s degree in Sustainable Landscapes from George Washington University, the vast majority of summer plant problems come down to one simple factor: water.

JR has spent two decades helping homeowners throughout the DC area, from suburban estates to city townhomes, create landscapes that offer four seasons of interest through thoughtful combinations of flowers, foliage, hardscapes, and focal points.

JR says to protect your plants during the peak of summer heat, pay attention to your watering. Everything else will be much more manageable when you get that right.

Watering Is 90 Percent of the Job

Watering makes up roughly 90 percent of what keeps a landscape alive and healthy through the summer months, accoridng to JR. Every other issue that can pop up, from pests to fungal problems, plays a much smaller role in comparison. If homeowners take away only one lesson from this article, it should be this one: Consistent, correct watering solves the overwhelming majority of summer plant problems before they start.

That does not mean the other 10 percent is unimportant, but it does mean that watering deserves the bulk of your attention and effort. If your plants are getting the right amount of water in the right way, they are far more likely to make it through even a difficult summer without lasting damage.

How to Tell When Your Plants Need Water

One of the trickiest parts of summer plant care is that different types of plants show signs of thirst in different ways, and if you do not know what to look for, you can miss the warning signs until real damage has already occurred.

Monitor the Plants

Perennials tend to be the most obvious communicators. When they need water, they wilt, drooping visibly in a way that is hard to miss. Trees and shrubs are more subtle. Instead of an overall droop, watch the tips of the branches. If the very ends of the branches on a bush or tree are beginning to droop, that is an early sign the plant needs water. Yellowing leaves or leaves that begin falling off are another warning sign that should not be ignored, particularly on trees and shrubs that were planted within the last few years.

Keep an Eye on the Weather

Beyond watching the plants themselves, pay attention to the weather. If it has been hot and dry for a week or more, that is a signal to start watering proactively rather than waiting for visible stress. JR pointed to a drought several summers ago that stretched on for weeks and ended up killing trees that had been established in the landscape for 20 years, along with numerous shrubs, simply because they were not given supplemental water during the dry stretch. In one particularly painful example, an entire row of Leyland cypress, which already have notoriously weak root systems, lost one or two plants in the middle of the row, leaving permanent gaps that could never really be fixed.

A Simple Watering Schedule for Dry Summer Weather

So how often should you actually be watering during a hot, dry stretch? For trees and shrubs, JR recommends watering twice a week during drought conditions, with once a week as an absolute minimum. This does not mean running a sprinkler for an hour. In fact, running a sprinkler is not the method JR recommends at all.

Instead, water by hand with a hose directed at the base of the plant, right at ground level. This method takes far less time than most people expect. A tree might only need a few gallons of water, which can be delivered in a minute or two with a hose. For shrubs, the amount can be even smaller, sometimes just 30 seconds to a minute of hose time, or the equivalent of a couple of gallons from a watering can. Watering cans are a great option for shrubs because they make it easy to measure exactly how much water you apply, though they do require a bit more time and effort than using a hose.

For trees, apply the water to the ground out to the drip line, which is the area beneath the outer edge of the canopy where rainfall would naturally fall, and roots tend to be most active. This targeted approach ensures the water actually reaches the root zone where it is needed most, rather than running off or evaporating before it can soak in.

Why You Should Avoid Watering with a Sprinkler During the Day

While it might seem counterintuitive, overwatering is actually easier than most people think, particularly with grass. Watering during the hottest part of the day, especially with a sprinkler that sprays the leaves of your plants, can cause serious problems.

The biggest issue is fungal disease. When water sits on leaves during hot, sunny conditions, it creates the perfect environment for fungus to develop. There is also a risk of leaf burn, since water droplets on foliage can act almost like tiny magnifying glasses as they evaporate in direct sunlight, scorching the leaf tissue and leaving behind spots or damaged patches. This effect is more pronounced in certain plants, including thin-leaf varieties and large-leaf plants such as hydrangeas.

Instead, water the base of the plant and the surrounding ground rather than the foliage itself, and if you do need to water grass or other ground covers during the day, know that early morning is always the better choice. Morning watering helps prevent both fungal problems and leaf burn, giving plants time to dry out before the heat of the afternoon sets in. Grass and other low ground covers are really the only exception where daytime watering habits matter most, since sprinklers are the standard method for lawns and naturally wet the blades directly.

Watch for Signs of Fungal Problems

If you notice trouble on your lawn during the summer, it helps to understand the difference between fungal damage and other common culprits, like pest infestations. Fungal issues tend to look less patchy overall, though they can appear in patches in some cases, and the grass itself typically remains rooted and intact even where damage is visible. You may notice discoloration or visible spores in affected areas, but the grass blades will still be firmly attached to the soil, which is a key difference from other types of lawn damage discussed below.

Watch for Japanese Beetles in Early Summer

While watering is by far the biggest priority, pests can also become an issue as the weather heats up. Japanese beetles and similar species tend to breed early in the summer, particularly around June, and this is when you are most likely to notice the damage they cause.

Before the beetles emerge from the ground as adults, their larvae feed on grass roots, which can create noticeable dead patches in a lawn that has not been treated with a preventive product like milky spore. Once the beetles emerge, they tend to feast on the leaves of many ornamental plants, with hibiscus being a particularly common target in this region.

If you notice dead, thinning patches scattered across your lawn and you can rule out simpler explanations, such as a pet consistently using the same spot, it is worth having a lawn care professional come take a look. One helpful clue in diagnosing the issue yourself is how easily the grass comes up when you touch it. When beetle larvae have eaten away at the root system, the grass will lift up very easily because the roots supporting it are gone. If a lawn care company such as a well-known local provider is not already treating your lawn with a product designed to kill beetle larvae, that untreated lawn is more vulnerable to this type of damage.

Give Extra Attention to Sensitive Trees Like River Birch

Certain tree species are simply more sensitive to summer heat than others, and one of the most common examples in this region is the river birch. This is especially true for trees planted within the last two to three years, which have not yet had time to fully establish a deep, resilient root system.

Struggling river birches tend to show their stress through yellowing and dropping leaves rather than the subtle branch tip drooping you might see in other trees. If a river birch was mistakenly planted during the summer months rather than during a more favorable planting window, this kind of stress becomes even more likely. With consistent watering, most river birches will recover, but homeowners with a young river birch in their landscape should plan on giving it a bit of extra water throughout the summer for at least the first several years, and sometimes longer, to help it get fully established.

Bringing It All Together

Keeping a landscape healthy through the heat of summer does not have to be complicated, but it does require attention. Watch your plants for early warning signs of drought stress, whether that is wilting perennials, drooping branch tips on shrubs and trees, or yellowing and dropping leaves. Water deeply and directly at the base of the plant using a hose or watering can rather than relying on a sprinkler, aim for twice a week during hot, dry stretches with once a week as a baseline minimum, and always water lawns and ground covers in the early morning to avoid fungal issues and leaf burn.

If you are unsure whether your landscape is getting the right amount of water this summer, or if you are noticing signs of stress in your trees, shrubs, or lawn, reach out to a local landscaping professional for a closer look. A small amount of attention now can save you from losing plants that took years, or even decades, to establish.