The process of designing and planting a beautiful landscape, then watching healthy plants grow into maturity can be a rewarding experience. However, the path to a healthy landscape is not always an easy one, especially if poor drainage is a problem.
Aside from light availability, water movement and drainage are the biggest site-related problems standing in the way of healthy plant growth. Nothing slows down growth or kills plants as frequently as poor drainage.
The first step in correcting drainage problems is to understand where the water is coming from and why it is causing a problem.
Gutter downspouts are a major source of surface water flow. Downspouts often are located where it is convenient to install them, not where it is best for site drainage. One of the best times to evaluate your gutter and drain system is during a heavy downpour.
Soon after a heavy storm, check each downspout to determine how much water is flowing and where it is going. Is it flowing back toward your house or under a crawl space? Does the downspout water form a stream in the landscape? Where does it end up?
Another common source of drainage problems is improper grading of the landscape prior to landscape establishment. While it seems silly to state, it can never be said enough that, "water runs downhill." It sounds simple, but it is surprising how often a landscape is graded so water is directed toward the house or to an area where water ponds.
Water can also come from less noticeable places but still cause water problems. Air conditioner drains account for considerable surface water if not discharged in the proper location. Poorly designed irrigation systems can over-water certain areas, particularly paved surfaces, causing significant water runoff. Leaky hose connections and outside plumbing also can be sources of unwanted water.
Aside from the drainage problems that can be observed on the surface, there could be a lot going on underground contributing to poor drainage conditions. Poor drainage can be caused by variety of natural and man-made means. Some soils, particularly clay soils, drain very slowly.
Major landscape projects often require heavy equipment that can compact the soil, creating an artificial hardpan. There can also be problems when imported soil is layered over native soil. This is caused by differences in physical properties between the two soils and can be a problem with either sandy soil over clayey soil or clayey soil over sandy soil.
The easiest way to test your soil for drainage is to conduct a perk test. Dig a hole approximately 8 inches deep, fill it full with water and let it drain completely. Wait a day or so and fill it again with water. Monitor the time it takes to drain back down.
If it drains within minutes, you have excellent drainage. If it takes a few hours, you have adequate drainage. If it takes overnight to drain, you likely have a drainage problem.
To remedy such problems, it is highly recommended that you work with landscape architect or an experienced landscape contractor. Correcting a drainage problem is not typically a "do-it-yourself" job.
(Thanks to David Berle, UGA Horticulture Professor.)
Billy Skaggs is an agricultural agent and Hall County extension coordinator. Phone: 770-531-6988. Fax: 770-531-3994.