Spring Flooding in Lawns

Spring rain is easily one of the best things for our lawns, soils, and the natural world to remain in balance. While rain serves so many beneficial purposes, depending on climate, drainage, geographic location, and topography, you can experience a mass influx of water into your lawn. At Sunday, we’re here to help you manage the calm after the storm and get your lawn back on track after a spring flood.

Why Does Spring Flooding Occur?

Flooding within your lawn can occur for a multitude of reasons. Some likely culprits for the added moisture on top of your grass include: 

  1. Plain old regular spring rains
  2. Inclement weather (e.g. increasingly severe storm systems from climate change)
  3. Poor drainage or lack of drainage systems in the lawn 
  4. Low points (e.g. flood zones) or tough to manage topography in lawns
  5. Location of property, specifically lawns near large bodies of water or coastlines

Flooding & Turf Survival

The survival of your lawn will ultimately be contingent on a combination of several factors – including some things that are unfortunately out of your control and will take some patience to manage. When your lawn floods, the survival and resiliency of your grass will depend on: 

 

Your Grass Type. Below are the warm- and cool-season Sunday grass types that will have the greatest resiliency to flooding, along with some general estimates on how long they can withstand flooded conditions: 

  1. warm-season: bermudagrass (55 days)
  2. cool-season: kentucky bluegrass (35 days), tall fescue (35 days), perennial ryegrass (<35 days)

 

Duration of Submersion. Survival of your lawn will depend on a combo of the grass type and duration of submersion, some turf types are able to withstand submersion for longer. 

 

Depth of Submersion. Increased depth = increased potential for turf injury. 

 

Water Temperature. Essentially, the warmer the water is, the greater the damage. Injury significantly increases between 50-86 degrees F. 

 

Light Intensity: The increase of light or sun will increase water temperature, which will in turn cause increased injury to turf. 

 

Sunday ProTip: Beware of scalding caused by flooding. Scalding happens during the brief period where the grass is submerged in water under very warm temperatures due to a combination of submersion, water temperature and light. 

How to Assess Damage from Flooding

When determining the level of damage from flooding to your lawn, consider the following: 

  1. High Temperatures: This a main culprit for turf death, where anything over 80+ degrees F may result is turf death within days.
  2. Discoloration: Yellow or browning turf may occur due to loss of chlorophyll, loss of nitrogen in the soil from leaching and denitrification, or compromised roots that are unable to take up nutrients.
  3. Low Oxygen Levels: Low oxygen is an immediate effect of flooding itself – submerged grass cannot take in oxygen. In the case of long-term submersion, this may cause root hairs to die, which then causes the turfgrass to die.  
  4. Water Damage in Lawn: Depending on if this issue is related to geographic location, the following water damage is possible.
    1. Inland: Flooding from rivers brings silt and fine particles that may settle out of the water into your lawn.The additional particles (silt/clay) can smother the grass and impact the soil.
    2. Coasts: Flooding from oceans brings saltwater and salts can impact soil and plants. Why? They disrupt soil structure (salt does not allow for aggregation, which means soil separates) and plant tissue can be burned, causing yellow discoloration.

Is my Turf Dead? How to Check!

Bioassay Test: Cut a sample from your turf, bring it inside, and see if it will grow.

Smell Test: the simplest of tests is to smell your grass. If it’s dead, it will smell like sulfur due to decomposing plant material and anaerobic soil conditions. 

Crown Test: If your grass is dead the crown of the grass (not the leaves of the grass) will be brown and mushy.

Recover Lawns from Flooding with Sunday

  1. Do nothing and Do No Harm. Stay off grass and soil until water recedes.
  2. Remove Sediment. If a lot of sediment (silt/clay) accumulated on the lawn, try to shovel or powerwash off.
  3. Aerate & Incorporate. If unable or impractical to remove, aerate and incorporate (mix-in) into the existing soil. 
  4. Seed Your Lawn. To mend existing lawn, add grass seed.
    1. If cool-season: tall fescue, kentucky bluegrass
    2. If warm-season: bermudagrass OR plug/sprig warm-season species

Cited Sources

Coop Extension Suffolk County. Flooded Turf and Salt Overwash. University of Cornell.

Bauer. Repairing Lawns Following Flooding. University of Minnesota.

S. Bauer. Lawn care: spring floods and drought….really?. University of Minnesota