We all know what mulch is – it’s that stuff we pile around our plants to prevent any other plants from growing. That’s good, as far as it goes. But mulch is pretty limited in its ability to provide any other benefits to our gardens. And the need to constantly bring in more mulch from off site creates a variety of costs. Is there a better, more multi-functional way we can stop unwanted plants from sprouting?
Enter green mulch.
“What stops plants from sprouting?” some inventive gardeners asked themselves. One answer is herbicides. Another answer is the absence of sunlight, water, and soil. But a third answer is other plants. In general, a plant simply can’t grow in a space already occupied by another plant. And so these creative gardeners came up with a simple strategy: to keep out plants you don’t want, fill all the available growing space with plants you do want.
Well, how do you that? The trick is layers. In order to create a planting so dense that nothing new can squeeze its way in, the members of that planting community must grow in a variety of shapes and sizes, so that they fit around each other, leaving no room for anything else. A monoculture – of pine trees, corn, bluegrass, or anything else – will always be made up of repeating plant shapes with predictable gaps that can easily be colonized by opportunistic newcomers.
And in a dense, layered planting, gardeners have discovered that the real gatekeepers are the lowest-growing species. Trees, shrubs, and other tall plants will always have open space underneath that unwelcome guests can sneak into. In contrast, plants with a creeping habit – that is, plants that spread along the ground, putting a few leaves into any available spot and then stretching onward to the next opening – efficiently cover soil, making it very difficult for any arriving seeds to germinate and get a foothold on a new life.
This is green mulch – living plants that take up space and crowd out unwanted interlopers. It serves this purpose just as well as traditional mulch, while involving less long-term cost and maintenance, and providing a host of additional benefits associated with healthy plants.
Wherever you live, there is sure to be a native plant that will happily serve as your green mulch. These little plants may not be eye-catching showstoppers, but they pull their weight in the garden, helping the community as a whole to thrive.