Undies in the Garden

I buried a pair of underwear in my garden this summer and, for some reason, didn’t think to mention it to anyone else in the family.

The house painters found the undies first. I can only imagine their surprise and dismay when the leg of their tall metal ladder hooked on the waistband of a pair of Hanes tighty-whities, underneath the snowberry bush. My son stumbled upon them later that same week. “Didn’t I mention the underwear?” I asked casually, when he approached me with concern in his eyes.

The underwear were actually part of a soil health experiment called “Soil Your Undies” that I learned about this spring. To participate, simple bury a pair of 100% cotton underwear in your yard or garden, and then dig them up again six to eight weeks later. If you have healthy soils with plenty of microbes, the underwear will be highly decomposed by the time you dig them up. If not, you might need to take steps to better nurture your soil. You can also do the experiment with a cloth handkerchief or square of fabric, but that would be nowhere near as fun and also won’t give the painters anything to talk about.

Me and my partially decomposed underwear.

“When we talk about soil, it can be a little boring,” explains Jennifer Hahn, an agronomy outreach specialist with the Lower St. Croix Watershed Partnership and University of Minnesota Extension. “This experiment is fun and helps people to understand what we mean when we talk about healthy soils.” Hahn is the founder of the Minnesota Soil Health Coalition and has buried underwear in farm fields across Minnesota, including at her own family’s farm in Chisago County.

Soil microbes include fungi, bacteria, archaea, protozoa, and even viruses that act to break down residue and make nutrients available for plants. According to the Natural Resources Conservation Service, one teaspoon of healthy soil contains more microbes than there are people on the planet. Microbes also help soil to store water and resist erosion. When we dig in the garden, we might just see dirt, but soil is actually a complex living system that nurtures flowers, trees, and farm-grown food.

After talking with Hahn about soil health earlier this year, I decided to try out the “Soil Your Undies” experiment in my garden at home. I chose an out-of-the way location on the side of the house (or so I thought!) and buried them on July 7, leaving the waistband above ground to help me find them again at the end of the summer. Two months later, on September 7, it was time to dig them up.

I feel embarrassed to admit how excited and nervous I was to dig up the underwear in my yard and see how much they had decomposed. It’s my job to teach people about landscaping with native plants and I’ve worked hard to cultivate a wildlife and water-friendly yard at my own house over the past ten years. If the underwear still looked like underwear, would I be exposed as a liar and fraud? 

When I dug out the undies, however, they were nothing but a spiderweb of hems and waistband, with small patches of dirty cloth between. I breathed a sigh of relief knowing that my garden had passed the test.

If you’d like to try the “Soil Your Undies” experiment in your own yard (and who wouldn’t want to?) be sure to use 100% cotton cloth or underwear. If you find your soil microbes to be lacking, here are a few tips for giving them a boost:

  1. Add compost to improve soil structure, feed microbes, and provide macro and micro-nutrients.
  2. Cover the soil in your gardens with mulch to help retain moisture.
  3. Diversify your flower gardens by adding plants that are native to Minnesota. Check out bluethumb.org/plants to find good options for your yard.
  4. In veggie gardens, rotate the locations where you plant different crops from one year to the next. Try a three-year rotation, to avoid planting the same family of vegetables without at least two years break in between. You can also plant a cover crop like kale, radishes, turnips, clover, ryegrass, legumes, or peas in the fall to reduce soil compaction and erosion during the winter.
  5. If you suspect your soil is lacking one or more nutrients, send a sample to the University of Minnesota to identify deficiencies and develop a correction strategy. Learn more at soiltest.cfans.umn.edu.