Don’t Kill Your Native Plants With Kindness

Watering plants
Overwatering plants can be deadly to the plants. Water only when soil 2-3 inches below the surface is noticeably dry.
Photo courtesy likeaduck. Some rights reserved.

We often hear that one reason to plant native plants is that they are easier to grow than non-native plants.

While there is a grain of truth behind this legend, the truth is that plants of any type need the right kind of maintenance regimen. It is true that properly selected native plants are, in principle, well adapted to our climate and soils but that doesn’t mean that native plants are immune to improper gardening techniques.

At Herring Run Nursery we get lots of feedback from customers about their plants. All gardeners know that some plant mortality is unavoidable, but some cases are avoidable. One avoidable cause of plant troubles we see regularly is overwatering.

In an effort to get their native plants off to a “good start”, we often see customers watering too much and too often.

Unlike the above-ground parts of plants, roots require ready access to oxygen in the soil.
Photo courtesy of Nick Harris1. Some rights reserved.

Plant roots perform a number of vital functions for the plant, including the uptake of nutrients and water. But the roots need energy to do this, and energy requires oxygen. The above-ground parts of the plant can photosynthesize oxygen from carbon dioxide, but the underground parts of the plant can’t do that.

Consequently, roots require ready access to oxygen in the soil. Normally this is not a problem since much of the pore space in most soils contains oxygen.

But if you water your native plants or trees too heavily or too often, that oxygen is continually displaced by water and the roots quite literally drown. In times of high temperatures like we’ve experienced lately, the top layer of soil can look dry even while the soil two or three inches down is saturated.

Our advice?

  1. Water your newly planted flowers, shrubs, and trees ONLY when the soil is dry to a depth of two inches below the surface. Use your finger, a pencil, or a chopstick to probe to that depth. Water only if the soil down there is noticeably dry.
  2. Water heavily but infrequently. Whenever you water your goal is to let the water infiltrate to a depth of 3 or 4 inches. This may mean watering for an hour or more, possibly pausing at points to let the water soak in. After a good rain, you might not need to water again for weeks.
  3. Once properly selected native plants are well established, with nice deep root systems, they may not need watering at all. After a year or two, the root systems of your native plants should be extensive: water only when you see signs that the plant needs it. These signs could be wilting leaves or premature color change in the leaves of trees.

Finding the right balance of care is one of the joys of gardening. Even with native plants, too much or too little of anything can be a bad thing.

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