Myth: Green Thumbs Are Born, Not Made


Step 1 to Garden Glory: Admit to Dragging Soil Through the Mud

In the dog-eat-dogwood world of gardening, plants get all the glory, while soil has, well, something of a reputation problem. Many of us think of soil as a dull means to an end—that is, if we haven’t already written it off as just plain dirty. Plants, on the other hand, are a grand reward for a job well done, or so it seems, for the happy few that were born plant whisperers.

Dark and crumbly, soft and earthy-smelling...ah, healthy soil. (NRCS)
Dark, crumbly, and soft-now that’s some good soil! (NRCS)

It’s time we give soil a reputation makeover—in truth, because the mind-boggling complexity of the stuff deserves our respect. Another solid reason to crush on dirt: Recognizing what’s beneath our feet as interesting, even wondrous, is your best bet for developing a green thumb and turning soil into the pretty flowers and tasty veggies we crave.

Why not just pour some nice fresh soil in the ground and leave uncovering its secrets to the pros? To root out the answer, we called on Bryant Scharenbroch, PhD, soil scientist with the Morton Arboretum and Liam Heneghan, PhD, a soil-loving ecologist with DePaul University.

Step 2: Get Down and Dirty in Soils 101

“What attracted me to soils is realizing there’s so much more to it than just dirt,” says Scharenbroch as he brings us along on a crash course in soil science.healthy-soil-nrcs

Made up of solids, liquids, and gases, soil is an elaborate, dynamic and living body. Within it dwell intricate living communities that are vital to our food system, our water supply, our atmosphere, and the environment as a whole.

It’s also not the monotonous matter we make it out to be, as its physical, biological, and chemical properties change dramatically over space and time.

In fact, healthy soil is entitled to some serious thanks for providing critical ecosystem services, explains Scharenbroch. These impressive credentials include:

  • For plants: Serving as a medium for plant growth and providing air to roots
  • For water: Regulating water, from its flow to rivers and lakes, to preventing erosion (ie, watch the video!)
  • For decomposition: Recycling raw materials/organic waste into humus, a.k.a. nutrients for plants and other organisms to uptake
  • For habitat: Providing habitat for tiny creatures in the form of a truly epic food web

What exactly is it that makes soil so complex? In a mouthful, says Heneghan: CLORPT. Published in 1941 by Berkeley scientist Hans Jenny, the acronym (and its accompanying complicated equation) identifies the factors that determine soil formation: climate, organisms, relief, parent material, and time. Never heard of it? Heneghan thinks this equation is as groundbreaking as Einstein’s—but unfortunately for soil scientists, nowhere near as sexy.

Of course, one could spend lifetimes on topics like climate and time, so for now we’ll stick to the factor with most here-and-now relevance to your green thumb potential…

Step 3: Dig Those Tiny Creatures

Did you know that there is more biodiversity underground than above?

    In the Midwest, the soil below one square yard of woodland could contain 200+ species of insects, crayfish, and spiders and up to 1000 species of soil animals in total. (Jay Sidebotham)
In the Midwest, the soil below one square yard of woodland could contain 200+ species of insects, crayfish, and spiders alone. (Jay Sidebotham)

According to the USDA’s Natural Resources Conservation Service, one teaspoon of soil can contain up to 7,000 different species of tiny living creatures (aka organisms). And according to the Soil Science Society of America, the organisms in one tablespoon of soil outnumber human population on Earth.

These microscopic wonders provide free help for gardeners, thanks to their mighty contributions in breaking down organic matter, exchanging gases, and providing food to plants via their roots. But in order to give your garden all that love, those little guys need to eat. And healthy soil is their bread and butter.

Step 4: Our Top 6 Tips for Feeding the Soil

Now we’ve established that soil a.) is not totally boring and b.) provides gardeners everywhere with good, cheap labor, how to return the favor? Here are some basic ways to promote soil health around your home:

Ask for help, while learning to understand the cues. The perfect soil typically isn’t made overnight, which is why testing soil chemistry with your county extension service is a good place to start. But you can also tell a lot from the presence of critters and physical clues like color and texture. As time goes on and you get to know your soil, you’ll be able to diagnose and predict its needs yourself, says Scharenbroch.

Understand that fertilizer is no cure-all. It’s easy to buy into package promises of fast growth, but overusing fertilizer disrupts plant communities and pollutes water. In fact, Heneghan says plant communities with the highest diversity (think rainforests and prairies) tend to be on soils with relatively low fertility. Your garden takeaway? You may not need to use fertilizer, especially if you’ve got a variety of native plants growing. If you do, be sure to use organic and ask your garden supply store for advice on amount.

One quick way to get soil savvy? Take a cue from these Arbor Day volunteers and get dirty already!
One quick way to get soil savvy? Take a cue from these Arbor Day volunteers and get dirty already!

Avoid applying pesticide. Chemical fertilizers and pesticides can be really tough on soil microorganisms, according to the USDA. They also harm the many “pests” that are actually beneficial to your garden ecosystem. One green garden strategy is to implement natural practices, such as integrated pest management.

Go for plant diversity. Limiting growth to one or two species of plants limits the diversity of microorganisms in the soil over time, because different soil microbes thrive on different plants, according to USDA. And since biodiversity in the soil is itself an indicator of soil health, this generally means that achieving more diversity above ground helps make things healthier below it, too.

Keep the soil covered as much as possible. Using living plant material (like cover crops) or dead material (like mulch, clippings, or leaves) to cover the soil during growing season helps it maintain consistent temperature and moisture. It also promotes root growth, making for improved soil structure. (Here’s some more on that from the UN’s Food and Agriculture Organization.)

Apply compost. Compost is nature’s easiest form of recycling. Mixing food waste and other composted materials into soil provides a gradual, steady supply of plant nutrients over time. Using compost on the soil also improves its ability to absorb water and encourages microbes to eat and poop, providing natural recycling. Plus it helps you save waste from your kitchen and yard scraps. How to achieve this eco-win? Check out the EPA’s quick guide to home composting.

Now that we’ve covered why soil health matters and how you can promote it, we’re well on our way to…

Step 5: Talking Dirty (or Not) to Your Soil

Feel free to borrow this line: Hey baby, I’ll get my hands dirty with you anytime.

…Okay, that’s awkward. But even if your approach to soil doesn’t include seduction, poetry, or song, there does seem to be something to the notion that, like plants, you can develop a relationship with it.

“Soil has remarkable properties that you don’t get from simply looking at it as a dead thing,” muses Heneghan. For one thing, dirt isn’t dead—it’s a “curious” mixture of living, dead, and never-alive. He believes that all you really need to develop an intuitive relationship with soil is a little knowledge, trust, and, yes, affection.

Will understanding soil help make even the brownest thumb green? Survey says, yes!

EcoMyth Outcome: Myth Partially Busted; Fully Enriched

You don’t have to be born with green thumbs. You can turn yours green by building an informed and intuitive relationship with soil.

One Green Thing You Can Do

Feed the soil with compost to enrich it naturally, while reducing waste.

GreenThumbs-OneGreenThing-EcoMythsOther ways you can help:

  • Put our Top 6 soil tips into action (see above)
  • Set aside a mini leaf litter reserve in a small, out-of-the-way section of your yard, where the soil can get healthier just by being covered
  • Teach your children to appreciate soil, too, from actually playing in it to organizing activities like DIY soil crayons
  • Look for exhibits about soil at public institutions (ones to try: The Field Museum’s Underground Adventure or the California Museum’s Dig It! The Secrets of Soil).