Why Plants Are Better at Mulching Than Mulch

If you enjoy spreading wood mulch every year in your landscape, then by all means ignore this post. If you enjoy pushing heavy wheel barrows and carefully navigating plant stems and branches without breaking anything, move along. However, if you’re into less maintenance, more wildlife, and more environmental sustainability, then follow me into cultivated wildness.

Wood mulch has nothing on plants!

1) Wood mulch is touted as a way to improve soil and conserve soil moisture. It’s true, it does these things, and can be valuable around newly-planted trees as well as an initial, one-time application at planting time for perennials. Soil organisms digest and incorporate wood mulch, building the upper layer over time, and mulch is great for saying “keep away” around tree trunks.

But thick layers of plant communities shade the soil with their leaves, which cool it down and robs sunlight from weed seedlings. Plant roots also rob water and nutrients from weed seedlings while amending soil naturally over time. Take prairie grasses — 1/3 of their roots die each year, adding organic material. Many plants have evolved to punch down into clay and open up air and water passageways, while plants with fibrous roots can build up sandy and rocky soil so it holds more water over time.

2) When you cut down the garden in spring with a hedge trimmer, string trimmer, or mower, all that dead plant material becomes a mulch layer providing a lot of the nutrients that plants need — that’s why trees drop their leaves over their root zone, after all. Give the plants back to themselves!

3) Leaving plants up for winter helps them gather leaves around their bases, insulating them from winter cold, adding organic matter over winter and spring, and provides shelter for overwintering insects. The more plant layers and plant diversity you have, the more life you’ll have thriving in your landscape.

Wood mulch is beneficial, yes, but doesn’t hold a candle to more plants. If you can’t afford a lot of plants, try to choose those that spread by seed or runners (wild geranium, purple poppy mallow, zigzag goldenrod, solomon’s seal, blue mistflower, etc). Consider planting just the ornamental flower layers with forbs and shrubs, then sow in a grass or sedge groundcover; we love to suggest sideoats grama for this purpose if you’re working toward a stylized meadow look. Additionally, there are local and regional nurseries and growers that offer smaller plants for a smaller price, so you can buy more at once time. Some day, we hope the industry sells trays of plugs at nurseries to consumers planning larger beds.

What should you shoot for then when it comes to the number of plants in an area? Let’s keep it simple. Say you have 10 square feet — you could plant this with one shrub or three gallon-sized perennials. Or, you could plant ten or more smaller perennials. Some of these smaller perennials may be ground covers, some mid height plants, and one or two taller architectural plants. The point is to both layer vertically and cover the ground horizontally. Remember that any bare patches of soil might be good habitat for the 75% of our 4,000 native bee species that nest in the ground.

Finally, look at the numbers and tally up how much money you spend on wood mulch each year. Is it around $300? In three years that’s $900 — money you could have put into more plants, which means more habitat and less work for you as that habitat grows.