Last week I adopted some bearded irises from a friend’s garden. While it’s not the best time to move irises-when they’re in full bloom-it was necessary for a number of reasons: Gloria had to downsize her garden, she knew that bearded irises are my wife, Susan’s, favorite flower, and Mother’s Day was right around the corner.
As I lifted the irises out of the ground, I quickly discovered that Gloria knew the secret to gardening. The rich, black soil reminded of a radio interview I conducted with Roger Swain, the man with the red suspenders” and former host of The Victory Garden on PBS. I asked Roger, “What is the secret to gardening?” Quickly he replied: “It’s the soil, stupid.”
He’s right. Oftentimes we get caught up in the beauty and performance of ornamental and edible plants without remembering that the foundation for any healthy landscape, garden, or lawn is soil. A healthy soil allows air, water, and nutrients to be absorbed by plant’s roots and lets those roots roam freely.
How do you build healthy soil? Test the soil and add organic matter. A soil test measures the pH or acidity of the soil and the level of nutrients available for plant growth. Contact your local Clemson Extension Service office or acquire the soil sampling form online. Results from your soil test will indicate the amount of limestone or sulfur required to increase or lower the soil pH to an ideal range, which is between 5.8 and 6.5 for most vegetable and flower gardens, shrubs, trees, and lawns. If the pH is too low or too high, nutrients can get “tied-up” in the soil and not be absorbed by the roots. Also, maintaining an appropriate pH creates an environment that supports helpful soil-dwelling organisms, including earthworms.
The soil test results will also inform you of any minerals that may have to be added to improve the fertility levels of your soil. If your soil already has high levels of phosphorus and potassium, for example, there’s no need to purchase a fertilizer containing these two nutrients (the last two numbers on a fertilizer label). There’s already enough in the soil to meet the plant’s needs, assuming that the soil pH is in the desirable range.
Besides soil testing, holistic gardeners add organic matter. Organic matter improves soil tilth–its physical condition or structure. When added to clay soil, organic matter holds the clay soil particles apart and groups them into small pieces. This improved structure improves air and water movement in the soil, which translates to deeper and more extensive root development in our plants.
The kind of organic matter you mix into your soil is your choice. My grandfather liked to use rabbit and chicken manure for his vegetable and flower beds. My mother liked using fish in her rose garden. As a child I used to bundle fish heads, tails, and other inedible parts in newspaper and then bury them around her roses. If you’re squeamish about using these organic materials, then add compost or shredded leaves. Cover or “green manure” crops such as crimson clover or annual rye are relatively inexpensive sources of organic matter. Sow these crops in the fall and then turn them under in the spring to enrich the soil.
Some gardener forsake organic matter for gypsum or sand, believing that either of these amendments will “loosen” their heavy clay soil. Because our piedmont soils do not have an alkaline soil pH or high levels of sodium like the soils in the Southwest, don’t bother with gypsum. To improve soil structure, add organic matter and maintain the right soil pH by liming.
If you’ve ever attempted to “fix” clay soil with a few handfuls of sand, you’d be pretty surprised by the outcome. You may discover that your annual flower bed is better suited for making bricks instead of growing marigolds and petunias. Stick with organic matter.
I drove home with a two dozen irises in my trunk. As I glanced down at my blackened hands on the wheel, I knew that my wife will appreciate this Mother’s Day gift of passalong irises. But will the irises like my red clay?
Bob Polomski © 2016