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Trees in the rain

Can My Trees Get Too Much Rain?

June 4, 2019
Topics

That feeling you had singing, “rain, rain, go away” as a kid is exactly the way trees feel during an unusually stormy season.

Yes, trees love a hydrating flush of water when the soil’s dry and they need a boost. What they’re not so fond of is a stint of relentless rain.

Below, read about what happens when trees get drenched in too much water and what you can do to help them cope.

Rainfall's impact on trees: leaves and roots

So, what exactly happens to trees when they get soaked with too much rainwater? Their roots and leaves can have a bad reaction, threatening the overall health of the tree.
Just as tree roots need water to live and thrive, they need oxygen, too. It’s hard to imagine that roots get much air since they’re packed under heaps of soil, but there are actually tiny little spaces in the soil called pores that help make sure oxygen flows to tree roots.

Problem is, long periods of continuous rain can fill the pores, stopping roots from getting adequate oxygen supply. That leads to smothering and issues like root rot or other infections that can weaken or kill the tree. Even without an infection, trees may decline over time because their roots just aren’t functioning the way they should anymore.

Overly saturated soil can also cue wilted, yellow or fallen leaves. And, with the moisture that comes with rainy days, fungal diseases prey on tree leaves. You may spot problems like powdery mildew on rain-soaked trees.

Rainfall and tree growth

No matter how healthy the plant, too much water is stressful, and it can affect a tree’s ability to push out new growth.

Trees that lose leaves in the midst of a rainy spell might grow and thrive again if there’s ample time for the soil to dry and the tree to regain strength. Unfortunately, it’s a mixed bag. Some trees won’t continue to grow after this setback and may need to be removed.

When it comes to my trees, how much rain is too much rain?

A couple days of heavy rain won’t push trees past their tipping point. But above-average rainfall that sticks around for a long period of time is what harms trees. While there’s no exact measure of “too much rain,” an unusually high amount of rain in your area calls for an intervention.

How to help trees during above-average rainfall

We can’t stop Mother Nature’s showers, and sadly, some trees just won’t be able to recover from the damage of too much water. Still, there are a few things you can do to give your trees a better chance at survival:

  1. Avoid watering until the tree absolutely needs hydration. Even if the rain has dwindled down, the soil is likely still soaked. Dig down into the soil about six inches; if it’s moist or drenched, don’t water it.
  2. Hold off on fertilizer until the soil drains the excess water. Fertilizer prompts trees to put their energy toward new growth, but they need to conserve as much energy as possible while they recover.
  3. Wait for the next growing season to see if your tree is free of overwatering symptoms and healthily growing again. If you’re not quite sure what to look for, ask your local arborist to inspect the tree.

When the time is right, here’s how much water you should give your trees.

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