Mulching a garden can be great for multiple reasons: suppressing weeds, retaining moisture, and even improving the soil over time. With native plants, there are some different considerations, because the plants are naturally adapted to the native soil and therefore able to thrive without anything special added to it.
In practice, however, this doesn’t always work out for a few reasons: invasive plants are often widespread in the areas being prepared for natives, and young seedlings and transplants do greatly benefit from some extra help as they get established. Therefore, we often recommend mulching a native garden at the beginning, but the practice becomes less necessary as the plants mature.
If and when you do choose to use mulch in your plantings, the next part of the discussion surrounds the best types of mulch to use with natives. You’ll typically see recommendations extolling the virtues of more natural and living materials compared to materials like rock, plastics, landscaping fabric, and even commercial dyed wood mulches which can actively do harm to your plants and landscape.
The more beneficial alternatives, however, are given a variety of names: organic, living, green mulch and the like.
In some cases these terms are synonymous, but there are actually two very different concepts at play with the recommendation of “organic” vs. “living” even though you might assume those are synonyms as well!
Here’s what we mean.
What Do “Living” and “Organic” Mulch Mean? Quick Definitions
The word “organic” means relating to or derived from living matter, so that means mulching with any material that was formerly living.
That could be a wide variety of materials like plant scraps, grass clippings, leaf mold or fallen leaves, compost, or pine needles.
A “living” mulch, on the other hand, is not actually putting any material, organic or not, in your garden bed, but rather planting a short groundcover to fill the space in between your plants and serve the role of mulch.
(“Green” mulch usually refers to living mulch too, but if you see that term make sure to check what it is referring to!)
These plants still provide the same benefits like suppressing weeds and lowering soil temperatures, and they even add do things that no traditional mulch can.
For one you don’t need to add more each year because the perennial plants will reliably return each year, but using living plants also soaks up more rainwater and greatly reduces your runoff.
And by choosing native plants as your groundcover, you’re of course providing additional wildlife habitat and food (both nectar and foliage if you choose a host plant).
How to Plant a Living Mulch (Spacing, etc.)
This concept of living mulch also represents a shift in the idea of what constitutes good garden design. Most traditional gardens are defined by a few specimen plants spaced comfortably apart with commercial mulch filling all of the space in between them. (In some cases with dyed mulches it almost feels like the mulch is the more important design element than the actual plants!)
Here we much more closely approximate a natural setting where multiple layers of plants coexist and fulfill their specific niche while mutually benefitting each other in a variety of ways.
Because of this, you don’t need to worry too much about exact spacing ratios or anything like that.
The main idea is that you want to plant your larger plants first, and then use the living mulch to fill in the bare spots afterward.
If your other plants are spaced a couple of feet apart, you should only need one (or maybe two) “mulch” plants in between each larger one due to the tendency of the mulch plant to spread.
Smaller plugs are usually a better choice than larger pots, and you could try planting seeds but this can be a challenge to ensure survival and keep out unwanted plants if there is a lot of weed pressure.
If you choose to grow your living mulch from seed (which is a great way to save money), I recommend winter sowing or simply planting them in small pots and then transplanting into the ground once they’ve grown a bit larger.
Make sure to keep any transplants watered for a few weeks until they get more established (especially if temperatures are hot). It’s likely you’ll have to keep weeding for a few months as all of your plants mature. When they do, however, it’s a very maintenance-free way of enjoying the benefits of mulch!
What Native Plants to Choose for a Living/Green Mulch?
Typically you could choose any low-growing plant that is relatively hardy and resilient and slowly expands and spreads so it will fill the available space and also be able to fight off weeds.
One option that may be already growing in your yard is common blue violet (viola sororia), which means you could enjoy the benefits of living mulch without needing to buy anything new and just transplanting some into the area you need covered.
Another common recommendation is wild strawberry (fragaria virginiana) which even gives you another benefit in the form of a fruit that can provide food for you in addition to your local wildlife.
Another intriguing possibility in my eyes is Woodland Stonecrop (Sedum Ternatum). I love this plant due to its exotic succulent look which would likely surprise many that it’s native to the midwest and eastern US. It creeps and reliably forms a groundcover, but isn’t super aggressive so if you try it as a living mulch you’ll want to see if it can hold off the weeds you have in the area.
Carex (sedges) are another possibility. Carex Pennsylvanica in particular is a great choice as it’s extremely low-growing (up to only about 8 inches in height), spreads by rhizome, and can handle almost any sun exposure. https://edgeofthewoodsnursery.com/living-mulch-part-two-species-suggestions
Phlox subulata (creeping or moss phlox) is dense and forms evergreen mats of foliage.
Other plants we’ve seen recommended as living or green mulches include Golden Ragwort (Packera aurea) Prairie Smoke (Geum triflorum) Rue Anemone (Thalictrum thalictroides) Stout Blue-Eyed Grass (Sisyrinchium angustifolium) Wild Ginger (Asarum canadense), and fleabane (erigeron spp.).
As with most aspects of gardening, the specifics of your site (sunlight, soil type, moisture) matter a lot in terms of how successful you’ll be. So try out one (or maybe a few) of these options and see how they work for you!
If you’ve had success (or have struggled) with using a living mulch, let us know in the comments.
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