How to Increase Soil Drainage


The best soil for a garden is described as a loam that has good drainage and is rich in organic matter. To guarantee that plants develop in a healthy manner, the typical garden bed requires additional labour to be performed in order to enhance the soil’s drainage and to provide nutrients. In addition, not all plant species thrive in soils that are quite rich. Individual plant requirements might vary from a “perfect” loam to one that is deficient in nutrients and dry to one that is swampy and humid. Before incorporating amendments or altering the soil’s structure, it is important to think about the requirements of the plants you want to grow in the garden bed you are creating.

Soil Types and Drainage

Sand, silt, and clay are the three most common types of soil. Sand is composed of granules that are rather huge, and there is a lot of space between them. Clay has the smallest, most compact particles, which are flattened and contain very few spaces. Silt occupies the centre of the spectrum, while loam is created by mixing together all of the other soil types in about equal parts, in addition to organic material.

The University of Maryland Extension suggests that you take the time to dig a hole that is 12 inches deep and 12 inches wide in order to evaluate the capacity of your soil to drain water. The hole should be filled with water and allowed to drain. After a day has passed, it should be refilled, and you should time how long it takes for the water to penetrate the soil this time. A sandy soil is one that can absorb water at a rate of 4 inches or more per hour, while a clay soil that can only absorb water at a rate of less than 1 to 2 inches per hour has either poor drainage, a high rate of compaction, a layer of impermeable hardpan, or a high water table. Sand can be identified by its ability to hold large amounts of water.

Garden Soil Amendments

Add garden soil additions such as compost and well-decomposed manure as well as other amendments to the garden bed in order to increase drainage. Every year, Steve Albert, a Master Gardener, suggests working at least two inches of compost and other organic matter into the soil to a depth of between four and six inches. This not only enhances the quality of sandy soils by improving the capacity of the soil to hold water, but it also increases the amount of air space that exists between silty and clay soil particles. If there is a layer of hardpan under the garden bed that is impermeable, you should attempt to break through it so that water may drain more easily from the soil. However, breaking through hardpan may necessitate the use of expensive equipment; if increasing drainage is a problem that strains your budget, you should consider using alternative solutions.

The oft-repeated phrase “add sand to clay soils to increase drainage” is an example of a widespread fallacy that Illinois Extension Educator Christopher Enroth addressed in his presentation. When combined with sand and water, clay produces a soil structure that resembles concrete. There is only one way to modify the structure of a clay soil using sand, and that is to add equal parts sand and clay to the mix. This is obviously not a solution that can be implemented in most gardening situations.

If the location of your garden bed is in a low position that is prone to flooding, you may want to consider incorporating drainage features such as a gravel-filled trench or French drain, a dry stream or swale into the surrounding environment. You may also make well-drained beds for your flowers, fruits, or veggies by constructing raised beds and filling them with equal parts compost, coconut coir, or peat moss, as well as sand or perlite. This would be an alternative method.

Go With the Flow

Even while most plants need a soil that drains well, there are a few that thrive best in settings that are just slightly damp. Columbine (Aquilegia canadensis) and New England aster (Aster novae-angliae), both of which are hardy in USDA plant hardiness zones 3 through 8, swamp mallow (Hibiscus moscheuto), which is hardy in USDA plant hardiness zones 5 through 8, blazing star (Liatris spp. ), and purple coneflower (Echinacea purpurea), both of which are hardy in USDA plant hardiness zones

Be careful when planting water-loving plants in clay soil since they tend to grow in these conditions. Some, like the creeping Jenny (Lysimachia nummularia), have the potential to become invasive if they are planted in areas close to marshes and streams that have temperatures similar to those found in USDA zones 3 through 10.

On the other hand, the ideal soil for a rock garden might be one that is dry, has good drainage, and is sandy. Cacti and other succulent plants, which are members of the family Cactaceae, provide aesthetic appeal to a landscape while also using far less water than other types of plants.