Heavy rains can drown plants. (C) Carol Michel/maydreamsgardens.com
We’ve had a lot of rain. We already know that the rain has promoted fast growth and early blooms on perennials, trees and shrubs. It’s also contributed to disease problems, especially fungi, for many plants.
All the rain can cause the soil to be waterlogged, which means there’s decreased oxygen available for plants. A lack of oxygen can cause plants to drown. As of this writing, we’ve received 26.05 inches of rain. Our average is 19.65 inches.
“It is important to understand what is happening to plants growing in these conditions and what to expect later. I look at this as a wait-and-see situation,” wrote
Rhonda Ferree, a horticulture educator at the University of Illinois Extension, in a recent report.
Visible injury to trees and shrubs may not show up for a year or two. Waterlogged soil deprives roots of oxygen, reducing the ability of trees or shrubs to take up and provide necessary nutrients. That lack of nutrients is what may cause decline or damage. Perennials may already show an overall decline because of waterlogged soil.
Ferree also notes that flooded yards add a lot of weight to the soil, which may cause compaction. That also pushes oxygen from the soil, inhibiting a plant’s ability to take up nutrients.
“Although survival is directly related to a species’ tolerance of waterlogged soils, other factors are important, including the soil type; the time, duration and depth of the water; the state of the floodwater; and the age and size of woody plants,” she said.
“Unfortunately, little can be done to prevent damage to plants growing in waterlogged soils. If a woody plant shows injury symptoms, such as leaf drop, do not immediately replace it. Some plants will show initial injury symptoms and then recover”
Injury symptoms, which vary according to several factors, include slower shoot and root growth, leaf yellowing, leaf twisting, leaf drop, root death, increased susceptibility to attack by insects and disease, absence of fruiting, and death.
Some will recover and some may not, providing yet another example of how gardening teaches us patience.
