That feeling you had singing, “rain, rain, go away” as a kid is exactly the way trees feel during an unusually stormy season.
Trees flourish when they are supplied with water especially when the soilis dry and they need a boost. What they’re not so fond of are stints of relentless rain that either don’t soak into soil or cause saturated soils.
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 sit in saturated soils 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, as well. 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.
The 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 .
Overly saturated soil can also cause wilted, yellow or fallen leaves. And, with the moisture that comes with rainy days, fungal sporeseasily spread from leaf to leaf. 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 allow oxygen to circulate through roots. 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?
Will too much rain damage your trees? 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, especially with poor draining soils such as clay, 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.
To help ensure your trees stay strong and healthy after a storm, here’s how to manage flood damage to trees before it gets out of hand. Address concerns ahead of time by:
- Pruning dead or broken branches
- Re-setting or staking trees that are unstable or leaning
- Managing pests as needed
- Adding mulch to protect new sensitive roots and improve aeration
- Managing mineral nutrition with micro-nutrients and slow-release nitrogen sources
- Leaching soil where salt water has intruded to remove sodium
- Removing excessive sediment deposits to return soil level to original grade
Trees may take years to establish themselves after initial planting and grow tall enough to add any significant value to your property, monitoring is critical before, during and after severe weather occurs. If you're experiencing consistent heavy rainfall that may be saturating the soil , monitor your trees’ progress throughout those events. After all, trees' shade capability, impressive stature and natural beauty are among many reasons why they deserve your care and attention.
HOW TO HELP TREES DURING ABOVE-AVERAGE RAINFALL
- 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 .
- 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.
- Wait for the next growing season to see if your tree is showing damage symptoms of water-saturated soils from the previous season, or showing symptoms of good health. If you’re not quite sure what to look for, ask your local arborist to inspect the tree.