Well-Drained

Well-drained¹ soils allow water to seep through and drain to the deeper water table. They also keep plants from partially suffocating or even completely drowning after massive rains. What we want, as gardeners, is evenly moist soil, not waterlogged soil. Well-drained soil accomplishes this, even after heavy downpours.

We all know plants need water, but plants can also suffocate from too much of what is normally a good thing. In nature, plants that grow in environments where their roots are constantly in water have mechanisms for bringing air down to their roots—the pneumatophores, or “breathing tubes,” of black mangroves are one example. In short, plants’ roots need air to survive—not large pockets of air that would dry them out but small, continuous pores and macro-pores through which water can drain and oxygen and other atmospheric gases can move and be present. 

Plants without special adaptations to bring oxygen to their roots, including all of our garden plants, suffer severely from partial suffocation in waterlogged soils and drown completely in completely saturated soils.

Blossom end rot on tomatoes is just one example of such partial suffocation. It actually stems from a lack of calcium, but that lack is caused by an inability of the roots to absorb calcium due to the soil being waterlogged (or, conversely, so dry that little absorption can take place).

As a small child often tasked with watering the hundreds of plants growing in the beds, tubs, and buckets that surrounded our house—a place not-so-lovingly called “The Jungle” by our neighbors with their predictable suburban yards—I learned this lesson the hard way. Not wanting to get berated for under-watering and never imagining a plant could have too much water, I held the hose on one particular plum tree in a bed bordering the house for quite some time. I stood there, and stood there. . .and stood there, holding the hose, losing track of time, thinking my dad would be especially proud. Boy, was I wrong; I drowned the tree. Dead as a doornail. 😳 I also partially flooded the basement, and destroyed a brand-new television with my zealous ignorance. Much to my surprise, I didn’t get chastised, however, I’m guessing because correcting one of his children for doing “too much” work was not the message my dad wanted to send.

Long story short, plants can have too much water. Give them well-drained soil, and the possible problem takes care of itself. Sandy soil is naturally well-drained, the sand particles naturally creating the pores healthy soil needs. However, sandy soils often contain fewer nutrients (i.e. aren’t very rich) and organic matter. Loosening rich soil that’s already full of organic matter is a much better alternative, creating the pores your soil needs yourself.

This is also why it’s important to site new gardens on ground that drains well naturally. If poorly drained ground is your only option with adequate sunlight, know you can improve your drainage on poorly drained sites, first through loosening techniques like double digging and later through more dramatic actions like tiling if needed. However, if you have another option with lots of sun, why not start with well-drained ground from the start and save a lot of extra work? You can tell the ground is poorly drained if it keeps standing water on it at any time during the year. Also, after the soil has dried out in spring, dig around a couple of days after a good rain and see if the soil is wet and sticky or evenly moist. While digging, also notice the color and texture of the soil. If you have the option, go with the darker, less sticky, more friable (easily crumbled) soil. It’ll be easier to turn into an ideal soil as it’s already on its way.

As mentioned above, well-loosened soil helps with drainage, but it has many other benefits as well.

1. _{One could, similarly, argue that well-loosened and well-drained soil are the same thing. This, however, is not always the case. Sandy soil is one example of soil that can be well-drained but not well-loosened.} ↩︎