Every August the phone starts ringing with a version of the same question. The tree looks fine in June, and by the middle of August it is dropping leaves onto a yard that has not seen real rain in five weeks. Is it dying?

Usually not. But the difference between a tree shedding on purpose and a tree in actual trouble is worth knowing, because the second one has a short window.

Shedding is a strategy, not a symptom

Leaves are where a tree loses water. When soil moisture drops and the air is pulling hard, a tree that cannot keep up will drop some of its canopy on purpose to reduce the load. It is the same logic as taking sail down in wind.

So a healthy tree in a Houston August that thins out somewhat, drops its interior and lower leaves first, and keeps a normal-looking outer canopy is doing what it is supposed to do. It will look thin, it will make a mess, and it will be fine.

The pattern is what tells you which situation you have.

Reading the pattern

Inside-out and bottom-up thinning. Interior leaves and the lowest branches go first, outer canopy holds. This is normal shedding. The tree is prioritizing the leaves that earn the most sunlight.

Top-down browning. The upper canopy browns or thins while the lower canopy still looks reasonable. This is the one to take seriously. Whatever is wrong is upstream, in the trunk or the roots, and the top is the farthest thing from the water supply so it fails first.

One side only. A distinctly one-sided decline usually means something happened to the roots on that side. Trenching, a new driveway, a utility cut, compaction from equipment parked on the root zone. Often something from a year or two ago that is only now showing.

Green leaves dropping. Leaves coming down while still green, rather than yellowing first, is not ordinary drought shedding. On oaks especially, that is worth a look.

Scorched margins. Brown, crispy leaf edges with green centers is classic heat and drought scorch. Unpleasant to look at, generally survivable.

Watering, done in a way that helps

Most summer tree watering does nothing useful, because it is done the way lawn watering is done. Trees want the opposite of that.

Deep and infrequent beats daily and shallow. A sprinkler that wets the top inch every evening trains roots to stay shallow, which makes the tree worse off next summer. A slow soak that gets water down eight to twelve inches once a week does real work.

Water the drip line, not the trunk. The absorbing roots are not against the trunk. They are out under the outer canopy and beyond it. Watering the base of the trunk mostly waters the part of the root system that does not drink, and keeping the trunk flare constantly wet invites rot.

Slow is the whole trick. Houston clay sheds water when it is dry and hard. Fast water runs off and leaves before it soaks. A hose at a trickle moved around the drip line over a couple of hours, or a soaker hose in a loop, gets far more into the ground than a sprinkler running at full pressure.

Mulch does more than watering does. Two to four inches of mulch over the root zone cuts evaporation, moderates soil temperature, and keeps the mower away from the trunk. Keep it off the trunk itself. The volcano of mulch piled against the bark that you see everywhere holds moisture against the trunk and causes the rot it looks like it is preventing.

Do not do these things in August

Do not fertilize a stressed tree. Fertilizer pushes new growth the tree cannot support and can burn roots in dry soil. If it needs feeding, that is a fall or late-winter conversation.

Do not do heavy pruning. Cutting removes the leaves the tree is using to recover and opens wounds in the hottest, most pest-active part of the year. Deadwood and genuine hazards come out any time. Shaping and thinning wait.

Do not assume it is bugs. Borers and beetles show up on trees that are already stressed. Treating the insects while ignoring the water rarely changes the outcome.

When it is more than heat

Call someone if you see any of these:

Top-down decline, especially on an oak
Mushrooms or conks growing from the trunk or root flare, which points to internal decay
Bark splitting, sloughing, or coming off in sheets
A distinct lean that is new, or soil heaving on one side of the base
Sudden total leaf drop rather than gradual thinning
Sawdust-like frass or small round exit holes in the trunk

Several of those describe structural failure risk rather than tree health, and August is not far from the part of hurricane season when a compromised tree becomes a roof problem.

What the fall looks like

A tree that shed leaves under drought stress this summer will usually leaf out normally next spring, and may look somewhat sparse for a season while it rebuilds. Keep water on it through September and October, which people stop doing the moment the weather turns pleasant even though the ground is still dry. Mulch it. Leave the pruning until the tree is not fighting for its life.

If you are looking at your canopy and cannot tell which pattern you have, that is a reasonable thing to have someone look at rather than guess. We cover Houston, Conroe, The Woodlands, Spring, Tomball, Cypress, Kingwood, Humble and Katy.

Why Your Tree Is Dropping Leaves in August: Reading Houston Heat and Drought Stress