When shopping for plants, you have probably read plant tags that suggest things like “needs full sun, needs part shade or needs well-draining soil.” But what is well-draining soil? This is a question I’ve been asked by many of my customers. Read more to learn the importance of well-drained soil and how to get a well-drained garden soil for planting.
What Does Well-Drained Soil Mean?
Simply put, well-drained soil is soil that allows water to drain at a moderate rate and without water pooling and puddling. These soils do not drain too quickly or too slowly. When soil drains too quickly, the plants do not have enough time to absorb the water and can die. Likewise, when soil does not drain quickly enough and plants are left in pooling water, their oxygen intake from the soil is reduced and the plants can die. Also, plants that are weak and suffering from insufficient watering are more susceptible to disease and insect damage.
Compacted and clay soil can drain poorly and cause plants roots to sit too long in wet conditions. If you have heavy clay or compacted soil, either amend the soil to make it more porous or choose plants that can tolerate wet areas. Sandy soil can drain water away from plant roots too quickly. For sandy soil, amend the soil or choose plants that can tolerate dry and drought-like conditions.
To test the drainage of a planting site, dig a hole that is about a foot wide and a foot deep. Fill the hole with water and allow it to all drain out. Before the hole has time to dry, refill it with water again. This time, using a ruler, measure the drop in water every 15 minutes for an hour.
- After an hour, if the soil has drained only an inch or less, this is an area with poor drainage.
- If the soil has drained about one to six inches in the hour, the site is well draining.
- If more than six inches of water was drained in the hour, your soil is draining too quickly.
Creating a Well-Draining Soil
Compacted, clay and sandy soils all benefit from being amended with rich organic materials. It is not enough to just add sand to clay soil to improve drainage because that can just make the soil more like concrete. For areas with poor drainage to either extreme, too wet or too dry, thoroughly mix in organic materials such as:
- Peat moss
- Shredded bark
Nutrient rich, properly drained soil is very important for healthy plants.