Soil: The most important aspect of gardening

I recently attended another native plant conference. After having spent most of my garden design career planting ornamentals – often Asian plants -- I'm still not a natives zealot, but I like to plant them among the ornamentals in gardens and have the best of both worlds.

I’ve already admitted to being a Doug Tallamy groupie, having heard him three times this year alone. His message about sharing our space with those birds and insects that evolved in it is compelling.

His book, "Bringing Nature Home," is excellent and if you have a chance to hear him speak at a local event, don’t miss him.

Now I will have to be a Jeff Lowenfels groupie, too. His book, "Teaming with Microbes: The Organic Gardener's Guide to the Soil Food Web (Revised Edition)," (Timber Press, $24.95) sounds like science. It actually is science, but totally readable and, in places, amusing.

Jeff is a wonderful speaker, like Doug, and he tells us in easily digestible bits about the vast life in the soil.

Healthy soil is alive

Bacteria, fungi, protozoa – miles and tons of living creatures make life on this planet possible. They feed the trees and the plants completely without our interference. Some plants have specific bacterial and fungal soil associations and requirements, while others are generalists.

I used to think I was doing something good by tilling heavy soils, adding nutrients like greensand, phosphorous, alfalfa, etc.

I would till until the soil was like cake flour and then plant perennials in it. Fabulous crops of lamb’s quarters would grow, but the perennials would limp along. So I stopped tilling and started planting in a hole dug to suit the plant going in – avoiding ruining the structure of the soil.

And the results were much better.

The soil-plant relationship

Now I understand the explosion of lamb’s quarters. This weed and others in the family of Chenopodiacae (spinach, beets, and quinoa) don’t form relationships with the in-soil critters. Once I had tilled all the critters to pieces and destroyed the soil structure, any plant that relied on in-soil flora and fauna for vital nutrients, water, and protection would struggle.

I made another connection. I have struggled to plant the exquisitely beautiful native sourwood (Oxydendron arboreum) for my clients. Most often the tree just died -- sometimes fast, sometimes slowly. In discussions with other designers, most have had the same difficulty.

Now I am wondering if the relationship with in-soil mycorrhizae (the world of in-soil flora and fauna) needs to be specific to sourwood. So, at this conference in the mountains of North Carolina, a shovel was available at Lowe’s and I dug up soil near sourwoods that were growing naturally – some up to 30 feet tall.

Now there can be a little science experiment here in Virginia, with a bit of soil at the roots of newly purchased sourwoods that I hope contain the right spores of soil flora and fauna to make the sourwood thrive. We’ll see.

As in every other soil situation, compost helps. So instead of doing what I used to do, compost will be the rule of the day and of the garden.

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Donna Williamson blogs regularly at Diggin' It. She's a master gardener, garden designer, and garden coach. She has taught gardening and design classes at the State Arboretum of Virginia, Oatlands in Leesburg, and Shenandoah University. She’s also the founder and editor of Grandiflora Mid-Atlantic Gardening magazine, and the author of “The Virginia Gardener’s Companion: An Insider’s Guide to Low Maintenance Gardening in Virginia.” She lives in the Shenandoah Valley of Virginia. To read more by Donna here at Diggin' It, click here.