You can amend your soil to improve its drainage by adding organic material, such as compost, manure, or shredded leaves. This technique will work whether your soil has poor drainage or very good drainage. It works by increasing the number of soil aggregates, which are groups of soil particles with lots of space between them for oxygen or water. Organic materials will work better and add more nutrition than other substances, like sand or perlite.
To amend your soil with compost, start by spreading a layer of compost two to four inches thick. Work the compost into the soil down to the top six inches to one foot by hand with a garden fork or a spade, or you can use a tiller. (Using a tiller too often will actually impair soil drainage by breaking up soil aggregates.)
Organic materials like compost are recommended for amending clay soils. You will often see references to amending clay soil with sand, but we do not recommend it. Amending clay soil with sand only works at a ratio much higher than is practical for most gardeners; otherwise, it creates a mixture similar to concrete.
- An alternative to soil amendment is the use of green manures or cover crops. These crops are planted in the fall and killed in early spring before they go to seed, either by mowing or by glyphosate. The green manure provides nutrition and aeration to the soil. For more information, check out our article How to Use Cover Crops with a Home Garden.
- If you’re growing just a couple of different types of plants in areas where soil drainage is a problem, try adding more diversity with new plants. As a result, you’ll have a more diverse range of microbes in the soil, which contributes to soil health.
- Break up soil manually using spading, trenching, or aeration techniques. Although tilling too frequently can cause soil to become compacted, you can till once to improve aeration, though it will disturb your earthworm population. Major problems with tilling come when people overtill their soil.
- To keep soil healthy, you should have plants growing there when the weather is cool as well as when it is warm. The roots of dormant plants are part of an ecosystem that contributes to the health of beneficial microbes in the soil.
- Soil particles are pressed together if compacted, impairing the healthy movement of oxygen and water through the soil. Avoid activities that cause soil compaction, including walking or driving on the soil or working in it while it is wet. Tilling your soil too frequently can also cause soil compaction. In general, you want to avoid interfering with the soil in any way so that natural processes like earthworm burrows and the spaces between soil aggregates can remain untouched. Disturb the soil as infrequently as you can.
- Redirecting water away from your garden can reduce the amount of water that comes into contact with your plants’ root zone. Different techniques can change the elevation in your garden to prevent it being a low-lying area. If your property is at a downspout or in a depression, redirecting water may be the solution for you.
- Hilling is traditionally used with potato plants, but you can apply it in areas with poor drainage no matter what you’re growing. Hilling involves creating a small hill (also called a berm) around each plant in the area with poor drainage. Hilling is really a method of redirecting water away from your plants, as some of it will soak into the hill and the rest will run off the sides away from the plants’ root zones.
- Installing a drain is another way to redirect water to improve soil drainage. You can use a French drain, the most common type of underground drain. A French drain is basically a ditch filled with gravel and covered with soil. You can also use subsurface tile drains, which are sections of perforated pipe laid 12 to 18 inches deep. Vertical drains can be used where you are planting trees or shrubs. They consist of three-foot to five-foot holes that have a diameter between 4 inches and 6 inches, dug next to the roots with an auger or post hole digger. These holes are filled with gravel, which maintains the structure of the soil while still allowing water to filter down and away from the root zone of your plants.
You don’t have to implement all of the tips we’ve provided here. Just choose a few that fit into your garden and your lifestyle. Before you know it, you’ll be seeing the signs of healthy soil, including flourishing plant life, a busy population of ants, worms, and beetles in the top six inches of soil, and a loose, deep soil texture that crumbles when moist. Your plants will look their best when they’re growing in healthy soil that offers plenty of drainage.
By Erin Marissa Russell
Source: How to Improve Soil Drainage in Your Garden – Gardening Channel