Gardening: What to do when the soil stays too moist

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Unusual weather this summer has taken its toll on many gardens. For many, drought is the problem, but what if it just keeps raining?

In some gardens, water stays on the surface of the soil or the soil stays muddy for hours after it stops raining. The best advice, then, is to move the garden to a place where the soil will drain better.

But of course you want to keep your garden where it is.

OK then plant Yellow Flag Iris, Sweet Flag, Marshmallow, Marsh Marigold, and other plants that like boggy soils.

But of course you still want to grow tomatoes, roses and marigolds in this sunny location.

Okay, it can be done. However, you need to bring some air into the soil, so provide water drainage so that the roots of these plants can breathe.

A WORK PIT

One approach is to drain the water to a lower point. The easiest way is with a trench or, if your garden is large, a couple of trenches. Of course, you also need an even deeper place into which the trench can drain.

The more clay there is in the ground, the more trenches will be needed to drain the water.

A drainage ditch doesn’t have to be large. The width of a shovel is wide enough for a garden. The deeper the trench, the greater the depth of the well-ventilated soil, so dig at least 18 inches deep. A gradual slope along the length of each trench, about half a foot per 100 feet, causes the water to flow downhill.

Trenches that criss-cross your yard don’t have to be an eyesore or an inconvenience. Imagine a garden where flat stones line trenches and are built as bridges over trenches that cross paths. The whole system can be an elegant water “feature”.

The effect could be similar to that of a classic Persian garden, although in the latter case the long, narrow waterways are used to bring water to the plants, not drain it away.

PARTY DREAMS

To drain water without changing the look of your garden, use perforated pipes that are buried underground.

Dig a trench as described above, then insert a black plastic pipe that is 4 inches in diameter. Available at home and hardware stores, the tube is corrugated to bend easily and perforated to let in water. Cover the pipe with a water-permeable cloth to keep out dirt and a layer of gravel, then refill the soil.

Make sure the outlet at the bottom of the pipe is either open or in a gravel bed in the ground.

As with digging, a deeper area is needed to drain the water into.

LIFT YOUR ROOTS

Instead of lowering the water level under the roots of your plants, you could give them air by lifting them above the water. Trees and shrubs can be planted on raised hills. The mounds must be wide enough for the roots to spread. How wide depends on the final size of the plant.

Raised beds provide well-ventilated soil for vegetables and flowers. Build a wood or stone enclosure for each bed, then add enough topsoil to fill each bed to a depth of a foot or more. The higher the surface of the bed, the greater the depth of the well-drained soil for the roots.

Just as long trenches lined with stone can carry you on a magic carpet into ancient Persia, a pattern of raised beds and the materials for their side walls and paths could take you to medieval Europe. Especially if the edging is made of sawn timber with beige gravel, for example, for the paths.

Or line the beds with roughly cut logs and put straw or crushed oyster shells in the ways, and you could instead envision harnessing a horse to a post outside this colonial American garden.

You don’t have to choose between trenches and raised beds to improve soil drainage – why not do both?

You can emulate the Aztec gardeners of Xochomilicho, who picked up dirt between their planting beds to raise them. Their gardens were actually laid out in the water and boats drove on the “paths”. Plant plenty of marigolds, a favorite flower in Xochomilicho, to add authenticity to such a garden.

Lee Reich is a regular contributor to The Associated Press about gardening. He has authored a number of books including Weedless Gardening and The Pruning Book. He blogs at http://www.leereich.com/blog. He can be reached at garden@leereich.com.