South Louisiana has been inundated by rain this year, and one thing we can learn from this weather is where our yards have problem spots and get to work on them for the future.

You’ve got a few options about what to do in these areas.

You can have additional drainage installed or you can divert the water to a storm drain or pond, but be sure not to point it toward your neighbors’ property.

One way to divert the water is to make a drainage swale by digging a shallow trench and lining it with rocks to prevent soil erosion. The trench needs to slope downward so the water drains away from the area where water is pooling.

A more expensive but worthwhile investment is to have a French drain or dry well installed. Both are installed below the topsoil to redirect the excess water.

A French drain is typically a long trench filled with gravel with a drainage pipe running from the house down the length of the drain and is covered up with soil or river stone at the grade level.

A dry well is used to collect water and release it to the surrounding soil instead of redirecting the water away from an area. It is placed at the end of a swale or French drain and is constructed of drainage fabric or a large metal or concrete basin with holes in its sides through which the collected water can drain out into the nearby soil.

You can also make a combination of the two: connect a French drain to a downspout and lead the water away from the house to collect into a dry well. However, if your soil does not drain well, a dry well will not be very helpful.

If you live in an area with little or no slope, it will be difficult to correct water problems without major groundwork. However, before spending big bucks, you can try a rain garden.

A rain garden is a low area in the landscape that is dug to collect rainwater and allow it to soak into the ground. Rain gardens help decrease soil erosion and reduce the amount of pollution in our waterways.

Rain gardens are often filled with plants that can tolerate standing water. Some great selections for Louisiana are bald cypress, river birch, live oaks, swamp red maple, pond cypress, rushes, sweet bay magnolia, southern magnolia, ironwood, parsley hawthorn, Virginia willow, American beautyberry, yaupon holly, Florida anise, dwarf palmetto, southern wax myrtle, Louisiana iris, buttonbush, river oats, muhly grass, ironweed, golden rod, cardinal flower, cinnamon fern, Texas star, swamp mallow, swamp milkweed, rudbeckia, rain and crinum lilies.

Locate a place for the rain garden at least 10 feet away from your house and 50 feet from septic tanks. Dig a hole 2 feet deep, then time how long it takes for 8 to 12 inches of water to disappear. If 10 inches drains in 14 hours, the drainage rate is 10 inches divided by 14 hours, or 0.71 inches per hour. Your target rate is 0.5 inches per hour or greater for an 18-inch-deep garden.

If the area drains at a rate lower than 0.5 inches per hour, you need to dig 30 inches. If the rate is less than 0.1 inches per hour, the area is not suitable for a rain garden.

You can make the area any size you want and in any shape, such as an oval or kidney bean shape. Mark the area with a garden hose, and begin digging down to 6-8 inches deep. You can use some of the soil to create a small berm to help retain water.

Make a trench, lay a flexible corrugated tubing from the downspout and run the length of the trench to carry the water from the roof to the rain garden. Make sure the pipe extends 1 foot into the garden. Use stones or rocks to line the trench to prevent erosion, and cover the pipe with soil or leave it above ground.

Fill in the area with soil. Add sand, organic matter or compost to improve drainage. Next, add plants that tolerate the most water to the center and those that like less water to the outer edges, which will be drier. Mulch to help prevent weeds.


Email questions to gardennews@agcenter.lsu.edu.