The two most important things you can do with a waterlogged lawn are assess the damage and repair it.
Although you may not be able to do anything to your lawn until the floodwaters recede, you can get an idea of the extent of damage to your lawn in advance and prepare accordingly.
The reason why flooding is so harmful to grass is that it limits the amount of oxygen and sunlight that the grass can access, thus limiting photosynthesis and the breakdown of sugars. Your garden will be damaged more if:
* Flood waters are stagnant and not fast moving.
* The lawn is completely submerged, unlike floodwaters which cover the roots, crowns or only part of the leaves. The deeper the floodwaters are, the more damage to the grass.
* The grass is actively growing. Dormant lawns will sustain less damage from flooding.
* Water temperatures exceed 50 degrees Fahrenheit. Grass immersed in water that is 50 degrees Fahrenheit or less can survive up to 60 days, while grass immersed in water that is over 50 degrees Fahrenheit will only be able to survive 4 to 6 days.
Once the floodwaters recede, your first task is to remove any debris and any silt more than half an inch thick. Clean up the grass and then try to soak the remaining silt into the soil. Good aeration can help increase oxygen levels in the soil, which the lawn desperately needs at this time.
You should also try applying a light fertilizer to the lawn a few weeks after the flood, to help the grass turn green and start growing again. Use only half the nitrogen per 1,000 square feet of lawn, and choose a fertilizer whose nitrogen is in a soluble or quick-release form.
Monitor your garden carefully over the next few weeks. If more than 60 percent of them are recovering, you may be able to perform a partial renewal by replanting or replanting the bare areas in late spring or early summer.
If less than 40 percent of the turf is recovered, it is more economical to perform a complete turf restoration. Kill and remove all remaining grass, and even any additional plant material in the soil.
Take this opportunity to test and improve soil pH, add organic amendments, and apply fertilizer before planting. You also have the opportunity to choose a different type of grass seed for your lawn, if you so choose. Make sure the type you choose is adapted to your region and climate. Plant grass when conditions are right, and keep the seeds moist until they germinate.
Although you may not be able to predict or prevent flooding, taking steps to repair the damage as soon as possible will keep Bermuda grass healthy and growing.