How to Fix Poor Soil Drainage

Poor drainage is the leading cause of death for garden plants. Adding organic matter will improve poorly draining soils. If you've tried that, though, and your site still retains water for hours after a short, heavy rain, further action is called for. A shallow trench and drainage pipe could solve the problem.

Difficulty:

Moderately challenging

Instructions

Things You'll Need

• Gravel Or Crushed Stone
• Perforated Pipe (black ADS Or White PVC)
• Wooden Stakes
• Agricultural Fabric
• Shovel
• Spring
• Spirit Level
• Tape Measure

1. Find a spot below the level of the garden where the water can drain away safely. A storm drain, dry well or drainage ditch is an ideal choice.

2. Measure the distance from the lowest point in the problem site to the drainage area. Then buy enough perforated 4-inch (10-cm)- diameter pipe to cover that distance. (Either black ADS or white PVC pipe will work fine.)

3. Dig a trench 18 inches (45 cm) deep and 12 inches (30 cm) wide, sloping downhill between the two points. Try for a drop of about 1 inch (2.5 cm) for every 10 feet (3 m) of ground.

4. 

   Test the slope by driving a stake into the soil at each end of the trench. Run a string between the two stakes, and use a spirit level to measure the drop between them (see A).

5. When the slope is at the correct angle, line the trench with about 3 inches (7.5 cm) of gravel or crushed stone.

6. 

   Lay the pipe on the stone (see B), and make sure any joints are fastened tightly.

7. Cover the pipe with agricultural fabric to prevent soil from clogging the perforations (tuck the cloth under the pipe at its uphill opening).

8. Add 6 more inches (15 cm) of stone over the pipe.

9. Replace the soil in the trench.

Tips & Warnings

• If your drainage problem is severe, you may need professional help. Before you try any do-it-yourself steps, consult a landscape contractor.

• On a large site, consider simply going with the flow. Many gorgeous plants, including cardinal flower, Japanese iris and astilbe, thrive in moist soil.

• Another alternative to expensive, time-consuming drainage correction is to grow your plants in containers.