We have less control over our plants during prolonged periods of rain or flooding than during drought. Unless they are in movable containers, there is little we can do except wait for the weather to change. (Once it does, the first thing to do is to follow the safety tips located here: Safety First! ) Then it is time to take stock of how our gardens held up.
If our soil is waterlogged, chances are good our plants are showing signs of stress – or soon will be. Plants may paradoxically look like they are wilting, but it is not because of too little water. Heavy rainfall can leach nutrients out of the soil, and waterlogged soil can block the exchange of gases necessary for plants to survive.
While we may not be able to prevent flooding, we should at least be on the alert for signs our plants are struggling. Start by watching for these signals:
Symptoms of Water Damaged Plants
Symptoms of water damage can look just like many other plant problems. Symptoms generally first appear on the leaves, although trees and shrubs may not exhibit symptoms for a year or more. (Next week’s Part Three will look at what to do about flooded trees.)
Signs our plants have been damaged by waterlogged soil include:
- Yellowing leaves
- Twisting leaves
- Dropping leaves
- Soft, spongy areas at the base of the leaf
- Wilting despite plenty of water
- Roots turning dark, often with a rotting odor.
- Lack of flowers or fruits
- Shoot dieback
Several factors determine how much damage is done to plants by flooding, including how long the soil is waterlogged, whether it is fresh or saltwater, the time of year and the type and age of the plant.
Flooding during warm weather is more damaging to plants because they are actively respiring and need more oxygen than during cold weather.
A short-term period of soggy soil probably won’t cause much damage. It is prolonged periods of flooded soil that cause problems. Although some plants, like willows, bald cypress, flag iris, and other bog plants, can adapt to long periods of floodwaters, most plants cannot; some can handle as little as a few days.
What to do for Waterlogged Plants
Unfortunately, once the soil is flooded, there is not much we can do but be patient. Just because a plant shows signs of distress doesn’t mean it won’t eventually recover. In the meantime:
- Don’t walk on the waterlogged soil. This will just compact it and cause more damage to distressed roots.
- If the plants were underwater, clean them off with a hose, to remove and sludge and another residue.
- Keep an eye out for diseases that will take advantage of stressed plants. The fungal disease, in particular, favors damp weather.
You can purchase a relatively inexpensive soil moisture meter at most hardware stores. A meter will tell you the percentage of water remaining in your soil. If you still have mud, you won’t need a meter to tell you the soil is waterlogged. But if you are wondering if it is dry enough for the roots to get the necessary oxygen, a meter will tell you when the soil has reached that level (usually between 40 – 70%).
For Flooded Container Plants:
- If the waterlogged plant is in a container and you can’t move the container somewhere sheltered, take the plants out of the container and let them sit and drain on newspaper or cardboard overnight. Once they have dried enough to see the roots, prune off any that feel slimy, before re-potting in dry soil.
- Potted plants that have been contaminated with sludge are best disposed of.
- Empty and clean pots, water trays and saucers, then wash them in warm soapy water.
- The soil in flooded containers will have lost most of its nutrients and will need a new dose of fertilizer. Use a slow-release organic fertilizer, to release the nutrients over time, as the plants recover.
Check back with Sterling Design & Landscape Resources for more tips in the coming weeks as we all recover from the recent floods. Call us at (281) 933-5197 to schedule a consultation, or if you need any assistance with the actions listed above.