The Well Drained Soil Tale
January 21st, 2006
We see the term in plant care descriptions all the time: “Must have well-draining soil.”
So, just what does “well-draining” mean, and how do we know if we have it?
In a nutshell, well-drained soil can be said to exist where water is removed from the soil readily (but not rapidly) and soils are not wet for significant periods of time. The best well-draining garden soil will consist of a nice balance of sand, clay, silt and organic matter.
But how do you tell if your soil is in need of improvement? Try this test in various locations in your garden when conditions are dry: dig holes one foot deep by two feet wide. Fill the hole to the top with water, and then time how long it takes for the water to completely drain. The ideal time should be between 10 and 30 minutes.
If the water drains in less than 10 minutes, it’s likely that your soil has a lot of sand in it. Adding organic matter will help immensely. Either till it into the soil or just add it on top in the fall or spring and allow nature to take its course.
On the flip side, if the water takes 30 minutes or more to drain from the holes you dug, you probably have soil that is heavy on the clay side. As with a sandy situation, organic matter will do wonders for your soil. So will raised beds comprised of a balanced garden soil.
Although many people think the well-draining qualities of sand will balance out the heavy water retention of clay, the opposite is true. What you create when you add sand to clay soils is basically…cement. Don’t do it. Again, dig in a good organic amendment or add it on top of your clay-ish beds each fall or spring and have some patience. The earthworms and Mother Nature will do their stuff in time.
To speed up the process, add crystalline Gypsum to the soil. This will dissolve quickly and chemically open up the soil so that is will drain. As an added benefit, your soil will become more acidic and much more condusive to rapid, lush plant growth.