Flooded Landscape and Garden

Excessive rain and flooding can wreak havoc on garden and landscape plants. Plants vary in their ability to withstand saturated soil or flooding.

This week's severe rainstorms and flooding in the eastern part of the United States leave a trail of destruction. Obviously people and homes (and pets) are the first worry, but in the aftermath there will be some consequences for many plants in the landscape.

Saturated soil causes problems for the plant roots, in that they are unable to find the oxygen they need to stay healthy. Prolonged wet soil can also encourage root disease problems. When the above ground portion of the plant is submerged, this interferes with photosynthesis and respiration. In flooded areas, there may also be contaminants in the flood water.

Keep in mind that it is best to avoid walking on or working soil that is saturated. Working it then can ruin the soil structure, and walking on it can contribute to compaction problems. In many ways, the best we can do is "wait and see."

Unfortunately, there is not too much for the gardener or landscaper to do except "wait and see." Woody plants have a surprisingly wide range of tolerances, some are able to withstand a year of thoroughly saturated soil while others are killed outright by just a few days of standing water or flooding.

A natural response to excess water will be (somewhat surprisingly at first glance) foliage loss. So although they may defoliate in response to root damage, there is a good chance many landscape plants will eventually recover from a temporary flooding that lasts just a few days.

Once the surface water is gone, some gardeners will attempt to increase the infiltration of oxygen into the soil by making holes in it with a garden fork. Push the tines down straight, working over the area of the root zone. It is important however to avoid walking on the soil while it is still saturated as this will cause additional compaction.

Vegetable gardens are severely impacted by prolonged saturated soil and flooding. Many vegetable plants will look beaten down by the heavy rain but if the soil is reasonably well drained, should tolerate the excess water due to the heavy rains. But if the garden was flooded, sadly the potential contamination by flood waters makes it unwise to eat the produce.

Flower gardeners will find mixed results in their flower gardens. Some flowers are able to handle prolonged saturated soil while others simply are not. Again, the soil drainage conditions will play a factor. And if plants were flooded or even underwater, you may suffer substantial losses.

Extensive plant losses can be heartbreaking, however in a way it does offer an opportunity. By this I mean it allows us to replant using only the plants we love best and that we know perform well in our garden. It also allows us to rework and rebuild the soil, adding organic matter and other amendments as needed. Early fall is a great time to plant, so take your time, evaluate, prepare the soil this summer, and be ready for planting then.

In the meantime, why not plant up a few containers to keep things looking cheerful for the rest of the summer.