Make Sure you Mow Your Swale properly!

Commercial mowers are large and usually can not mow to either side of a swale. This causes the thatch level of the sod to rise and slow the velocity of the water flow. As this happens, the soil will tend to stay wet and when it gets continually mowed, the mowers will cause rutting and water will start to pool. The way to deter this, is to mow either side of the swale where the blade is at the bottom of the swale and run the mower down the entire distance of the bottom of the swale on both sides at least once a month during the growing season. This will keep the grass blades and thatch to proper heights.

Beware of Rutting

This image shows rutting (left rear of image) caused by the large mowers. It also shows that the swale is over grown and almost nonexistent. Even though the sod looks ok, this is backing up water flow behind this area and causing drainage problems. Rutting can be prevented by “staggering” the wheels when the grass is mowed. Make sure to cut the bottoms of the swale to avoid thatch overgrowth in swale.

Properly Mowed Swales are Important

This image shows a properly mowed swale. Notice that you can see a “V” shape even through the grass.

What NOT to do.

NEVER plant trees or plants in swales. This will block water flow and cause serious problems. In this case, a large tree had been planted in the middle of a drainage swale between two homes. The tree’s roots grew large enough that the swale was completely blocked. On a heavy summer rain, the water had no place to go and actually flooded this home causing severe damage.


Planting Trees in a Swale is a Bad Idea

This image shows what happens when a tree is planted in a swale. Notice the water backing up behind tree and how wet the areas are.

Don't Forget to Mow Correctly!

This image shows a swale that is also not mowed correctly. Notice the height and color of the sod in the middle of the swale. All it needs is to be cut down each side so the water flows at the optimum speed.

Summary: Drainage swales need to be maintained. Swales should never be obstructed by planting trees, plants or any other possible obstructions. Make sure your yard doesn’t get “rutted” by mowers operating too fast through the same exact trails, stagger the tire lines. Small walk behind mowers are the best for maintaining the swale integrity.