Summer in Missouri can be brutal, not just for people, but for trees, too. Long stretches of high heat, strong sun, and little rainfall can leave even strong, mature trees struggling. But how do you know if your tree is thirsty? And how much water is too much?

At Hansen’s Tree Service, we often get calls in July and August from concerned homeowners asking: “Am I watering my trees enough?” or “Why does my tree look stressed even though I water my lawn?” The answer comes down to understanding how trees use water, how soil holds it, and how to water the right way.

Here’s what you need to know to keep your trees healthy and hydrated during hot, dry weather.

Why Summer Is So Stressful for Trees?

During periods of extreme heat and drought, trees face two major challenges:

• Increased moisture loss through leaves (a process called transpiration)
• Decreased moisture availability in dry or compacted soil

This creates a moisture deficit, especially in urban or suburban environments where soils are often poor and surrounded by pavement or turfgrass that competes for water.

Young trees, newly planted trees, and shallow-rooted species like dogwoods or birches are especially vulnerable. But even mature trees can suffer from prolonged dry conditions.

Signs Your Tree Needs Water

Look out for these common symptoms of drought stress:

• Wilting or curling leaves
• Leaves turning brown or yellow, especially at the edges
• Early leaf drop or thinning canopy
• Slow or stunted growth
• Cracked or dry soil around the root zone

By the time a tree shows visible stress, it’s already struggling, so proactive watering before a tree shows symptoms is key to helping your trees during dry periods.

So, How Much Water Do Trees Really Need?

Here’s a simple rule of thumb:

Most established trees need about 10 gallons of water per inch of trunk diameter per week during dry weather.

To measure trunk diameter, just take a tape measure around the tree at chest height (about 4.5 feet above ground) and divide the number of inches by 3.14. Multiply that diameter by 10 to get your weekly water target.

Or, for a simple estimate, for example, a 10-inch diameter tree would need roughly 100 gallons per week, or about 15 gallons a day, during a drought.

Best Practices for Summer Tree Watering

It’s not just how much water you give, it’s how and when you deliver it that makes the difference.

• Water Slowly and Deeply – Use a soaker hose, drip system, or even a slow-running hose. The goal is to get moisture down eight to 12 inches into the soil where the majority of feeder roots live.
• Water at the Drip Line – The drip line is the imaginary circle under the outer edge of the tree’s canopy. That’s where most of the absorbing roots are; not at the base of the trunk. Water in this zone to reach the active root system.
• Special Note for Newly Planted Evergreens – For the first season or two, water closer to the trunk and around the original root ball to ensure the roots establish well before expanding outward.
• Avoid Frequent, Shallow Watering – Sprinklers or short watering sessions may wet the surface but won’t reach the roots. This encourages shallow root growth, which in the long run makes trees more vulnerable to stress.
• Water Early in the Day – Watering in the morning reduces evaporation and gives the tree time to absorb moisture before peak sun and heat hit.
• Mulch Wisely – Mulching helps retain soil moisture and keeps roots cool. Use two to four inches of organic mulch, and keep it a few inches away from the trunk to avoid rot or pests. Hansen’s varieties of mulch are a great choice for healthy root zones.

What About New or Young Trees?

Newly planted trees need extra care. For the first two years, water them two to three times per week, depending on weather conditions. Use five to 10 gallons per watering session and always check soil moisture before watering.

A helpful trick: dig down four to six inches into the soil. If it feels dry at that depth, it’s time to water.

Can You Overwater a Tree?

Yes, you can overwater your trees, especially in clay-heavy Missouri soils that don’t drain well. Overwatering leads to root rot, fungal growth, and oxygen deprivation in the root zone. If the soil is consistently soggy or water pools around the tree after watering, you may be doing more harm than good.

The key is balance. Use your hands (and a soil moisture meter, if needed) to gauge conditions before watering again.

When in Doubt, Ask a Certified Arborist

Watering sounds simple, but every yard has unique soil, drainage, sun exposure, and tree species to consider. If you’re unsure whether your trees are getting what they need, or if you suspect your trees are stressed, consult with a certified arborist.

At Hansen’s Tree Service, we provide tree health assessments and can recommend customized watering strategies based on your landscape and tree species.

Keep Your Trees Strong All Summer Long

Drought stress is a leading cause of tree decline, but it’s one of the most preventable—with the right watering practices and a little planning. Don’t wait until your tree starts dropping leaves; proactive care during the summer can make all the difference.

Need help with summer tree care? Contact Hansen’s Tree Service today to schedule a visit from a certified arborist and keep your landscape healthy and thriving all season long.