Plants That Improve Soil Quality

Soil care and soil improvement are topics about which gardeners can talk endlessly (and they will!) Most types of garden require soil, and there are a variety of means to build the soil you need, ranging from compost to hugelkultur to fertilizers. Those are all useful approaches, but there are some other options too—including using plants that improve soil quality! Some plants actually enrich the soil as they grow; their interactions with the soil and its nutrients and chemistry may actually improve soil if used properly . So let’s dig in and learn a bit more about plants that improve soil quality and how we can use them in our garden spaces.

Gardzen Executive Summary

· Yes, some plants can improve soil just by growing in it!

· Some of these plants are nitrogen-fixers, meaning that they help move nitrogen out of the atmosphere and into the soil.

· Some plants move nutrients mechanically, meaning that their deep roots pull nutrients from the depths of the soil towards the surface where other plants can use it.

· You may already be growing some of these in your garden; in fact, many of them are both popular and easy to grow!

How Plants Can Enrich Soil

There are two primary mechanisms by which plants can enrich the soil around them. Some plants—mostly from the legume family—are nitrogen fixers, meaning that as part of their life cycle they add nitrogen back to the soil around them. These plants form symbiotic relationships with some helpful Rhizoba bacteria in the soil. These bacteria are attracted to the roots of nitrogen-fixing plants. When they establish themselves around those roots, they begin the process of pulling nitrogen out of the atmosphere (fun fact: the air we breathe is around 60% nitrogen) and converting it into compounds that the legume plants can use.  Nitrogen is a key element for plant growth via the nitrogen cycle which all living things are part of. The plants then repay them by producing organic compounds that the bacteria colony can use to feed itself. Everyone wins!

Other plants take a more mechanical approach to soil improvement.. Their deep roots pull nutrition up from the depths of the soil and move it closer to the surface, which in turn makes that nutrition more readily available to both the original plant and its neighbors. Over time, this improves the health and quality of the soil by promoting a rich and active soil biome and helping increase the diversity of plants in the area. This is generally a more long-term approach to soil improvement than using nitrogen-fixing plants, but it also yields richer nutritional results for the soil.

Now we get to the absolute best part: Many plants that improve soil quality are both easy to grow and already popular in gardens of all kinds! In fact, you may be growing some of them already and not even realize it.

Growing Plants That Improve Soil

So which plants help the soil? There’s a long, long list of plants that either fix nitrogen or move nutrients to the surface from deeper in the soil, so we’ll provide a list of each here. See if you can spot some plants you know—we just about grantee that you will!

Nitrogen-Fixing Plants:

· Beans

· Peas

· Lupines

· Clover

· Vetches

· Mimosa

· Acacia

· Mesquite

As you may have noticed, some of these are perennials of various sizes, and are thus long-term investments in soil quality for landscapes. Others are fast-growing ground-cover or garden plants, and are better suited if you want to use a cover crop or companion planting for soil enrichment. These helpful plants give us options for both use case and climate zone, and we’re grateful to them!

Plants That Move Nutrients to the Surface:

· Milk Thistle

· Borage

· Comfrey

· Daikon Radish

We wish this part of the list were longer, but these are the only examples we can find and confirm. We also have experience growing them and they’re fairly easy in most climates as either annuals or perennials depending. Again, these are a longer-term solution to plant-based soil improvement, but given how lovely and/or tasty they are we don’t mind having them in our gardens year after year.

Plants for Soil Improvement: A Beautiful Investment

We should all remember that these plants aren’t the only option for improving soil. We actually recommend using them as part of your soil improvement and soil health plans, rather than as a stand-alone solution. Nature is cooperative and collaborative, and our gardens should follow its example. We’re all part of the natural cycles around us, and we hope this article helps you understand one of those cycles and the role it plays in our garden spaces!