How to Improve Site Drainage

It seems obvious to most people that the tops of plants need air to live, but did you know that their roots need air too?

Good soil has open air pockets that comprise up to 50 percent of its composition. When it rains, or an area is watered excessively and is not drained away, these air pockets fill with water and the air is eliminated. Just as humans can't breathe under water, neither can plant roots.

Poorly draining property can be improved one of four ways. All attempt to get the plant roots out of soggy soil.

One way is to simply fill the low spot with soil and grade the entire area to create a very slight slope so the water runs off. Perfectly flat terrain will collect water and not drain well. This technique works especially well in smaller, shallower areas that are simply puddling for a short time after a rainstorm.

If the wet area is somewhat larger and deeper, and holds water for more than two days, I recommend putting in some type of draining mechanism. One method is to lay perforated tile just below the soil surface and run it out to a lower area. This is a convenient method that is completely inconspicuous. Another technique is to put in a drain cup or catch basin to quickly collect the surface water and carry it away below the surface through an underground solid tile.

Mounding the area to a height of 1 to 3 feet or more, if needed, is one way to place the plant's roots above the underground water. However, be aware that water can wick up through these mounds if they are inadequate in size. The mounds should be arranged not only for drainage, but also to create a landscaping asset. Wide and gentle, rolling mounds help break up an otherwise flat yard and can be visually pleasing.

Sometimes mounds will trap water at their base. You can eliminate this by running solid tile through the base of the mound to a lower area for better overall drainage.

For larger, nearly or already established plants that lie in wet areas, a modified French drain can be built to give the roots a drier growing area. Use a posthole digger beside the original root ball to a depth of two, three, or more feet and fill the hole loosely with large gravel. More than one hole can be used for larger plants.

When planting new trees and shrubs in heavy clay soil or what appears to be a possibly poor draining area, I recommend creating a modified French drain at the bottom of the hole in which the plant is placed.

For all new plants, in any location, I recommend planting the top of the root ball one to two inches higher than the surrounding soil. It is a good idea on balled and burlapped plants to dig carefully down into the topsoil to see where the original root level is. Then, remove any overburden before making the final height level decision. This guarantees better drainage than planting them level to the surrounding soil line.

Correcting drainage problems is not difficult, but for assistance, contact your local garden center, landscape contractor or commercial nursery grower. Better drainage is good for your plants and makes your landscape that much more enjoyable and easier to care for.