If your garden didn’t thrive this season—weak, yellowing leaves, few blooms, even fewer fruits, diseases, and pests, or just not lush as you’d hoped—maybe it isn’t the plants or what you call your brown thumb. Look down. Do you see a dark, crumbly, nutrient-dense soil with lots of earthworms and organic matter, or is it compacted, greyish, and hard to work? If it’s the latter, your garden problems are your soil. Make this year’s goal to focus on healthy soil in the garden. It is, after all, the foundation of your garden.
Here are a few quick ways to judge your soil’s health and what to do to improve it.
Workability And Compaction–Necessary for Healthy Soil in the Garden
Do you get big soil clods that don’t break up quickly when you dig in your garden? If so, your soil has low workability.
Does water runoff not penetrate the soil? That is an indication of compaction. An easy way to tell if you have compacted soil is to get a wire flag and stick it into the soil, marking where it bends. I flag a lot of gardens for clients, and many times, the wire flag doesn’t penetrate at all. The desired depth is six to twelve inches—easily—for the flag to sink in. Twelve inches is best.
Clay soil is not very workable (if you live in Western North Carolina, you know this), and compaction can happen in several ways, from heavy foot traffic, equipment or cars. Improving the soil is the first chore to a healthy, lush garden in our garden beds. Amending the soil is an annual job. Add organic material—leaves are perfect, read about that here—or a bagged amendment, compost, or manure to improve workability and compaction.
Workable, non-compacted soil is easy to dig in and has a good structure and tilth (see below). It allows for air, water, and nutrient circulation. If workability or compaction is a problem, address that first before treating plants for disease and pest issues or fertilizing.
Soil Structure And Tilth–Also, Necessary for Healthy Soil in the Garden
Rich, organic soil comprises different-sized aggregates that retain their structure when pressure is applied (rain, water movement). Soil aggregate health is vital in protecting organic matter, maintaining water holding capacity and drought resistance, and keeping erosion at bay.
Soil structure refers to the size and shape of soil aggregates and the pore spaces between them, arranged in a layer of soil. Soil structure is an important indicator of workability and permeability; soils that are well aggregated have “good soil tilth” and drain better than poorly aggregated soils. (Cornell University Cooperative Extension, Fact Sheet 95)
To check your soil aggregate health, dig a hole six to eight inches deep (the soil should be neither dry nor too wet). Separate a portion about the size of a soup can, and break it apart. You are looking for soil that is not granular, powdery, or “cloddy.” Good soil structure is porous but not “loose,” allowing water and oxygen circulation.
Again, good organic matter—compost, soil amendments, leaves—all improve soil structure.
Soil Organisms/Earthworms–May Be a Little Gross but Necessary for Healthy Soil in the Garden.
Earthworms are the aerators of your soil. They eat organic matter, and their castings infuse the soil with enzymes, bacteria, organic matter, and plant nutrients. They increase water infiltration and secrete compounds that bind soil particles together for better tilth. You can’t have too many of them. Dig six inches down and count the earthworms. Three is good, but six is better.
A thriving population of soil organisms (anthropods, pillbugs, fungi, beneficial bacteria, beneficial nematodes) is one of the best soil health indicators and, ultimately, garden health. The more that creeps and crawls in your soil, the less chance for unwelcome pests and disease. Each level of soil life does its part to break down plant residue and make more nutrients available for growth. Checking for organisms isn’t easy as most are microscopic, but spiders, beetles, centipedes are all good things in the garden.
I can’t say it enough—adding organic material is best, compost, amendments, leaves, manure. For most of us, compost and manure aren’t an option, and we don’t have time or space for composting, and we don’t have access to manure. Both can be purchased and are sold in Daddy Pete’s 40 lb bags to add to your soil.
Drainage/Water Availablity–A Must for Healthy Soil in the Garden.
This one seems obvious, but water should percolate into your soil at a rate of 1/4″ to 2″ per hour.
A simple test to check your infiltration rate is to take an empty coffee can (any can will work if it is long enough and can be pushed into the ground without folding) and remove the bottom of it. With the base removed, press the can into the soil until 3 inches remain above the surface. Fill the can with water, marking the water height and how long it takes to absorb into the soil. Repeat this several times until the absorption rate slows and your times become consistent. Anything slower than 1/2 to 1 inch per hour indicates compacted soil.
Water availability speaks to the ability of your soil to retain moisture. Make it a habit to observe your soil. How long after a good rain does your garden need water again? Gardens need an inch of rain a week, but if you find yourself watering in the middle of that week, your soil isn’t holding onto water properly for your plants.
Again, adding organic matter—compost, amendments, plant debris, leaves—will improve your soil and increase your plants’ health.
Note: the store sells Daddy Pete’s amendment products, and staff can help you determine which product is best for your soil health.
Written by Cinthia Milner, Landscape Consultant, and blog writer.
B. B. Barns Garden Center serves Western North Carolina, upstate South Carolina, and Tennessee.