4 minute read
Nature's Seed
Capture the Canopy with Living Mulch
By Skylar Christensen
Nature abhors a vacuum. And there’s nowhere she hates it more than in agriculture. Whether on the rangeland, the field, the landscape, or the garden, something is always trying to take over nothing. Leave soil bare and exposed for too long and everyone knows what happens. Farmers understand this and use cover crops and green manures to smother weeds, improve soil structure, and prevent erosion. Most gardeners also recognize this concept and employ a variety of tactics – some methods better than others.
One tactic I don’t care much for is the garden bed dotted with a handful of shrubs swimming in a sea of wood mulch. Negative bonus points for patches of exposed weed fabric! Unfortunately, this design seems to be favored by HOAs and businesses around the state. I get that plants take time to grow and fill in, and in the meantime wood mulch will at least provide some basic soil protection. But man does it look… unnatural. Instead of piling on loads of dyed wood product that will shift and let weeds invade anyway, we should be following the example of farmers (and nature) by planting living mulch in our ornamental gardens too.
I once had a horticulture professor who taught us to “capture the canopy” in our garden designs. In other words, install plants at a greater density overall and use shorter, spreading plants to fill in open areas around larger plants. When we capture the canopy we make it more difficult for weeds to establish. We also stabilize and enrich the soil, improving water and nutrient infiltration. The visual qualities of a plant-rich garden can’t be ignored either. Beds look lush, multi-dimensional, and natural when there’s no large open areas between plants.
There are numerous plants and groundcovers out there that make excellent living mulch, but here are three favorites I’ve used in my ornamental gardens over the years:
Sweet alyssum, Lobularia maritima, has just about all the qualities I look for in living mulch. It can be planted in large areas cheaply from seed and establishes quickly. It’s a shallow-rooted spreading annual and blooms all season until the first frost. It comes in a range of colors, but the short compact ‘Royal Carpet’ purple variety is my go-to. While the taller white varieties might get a little aggressive, ‘Royal Carpet’ stays short and polite in the garden, growing right up to but not overtaking my young perennials. It also smells like honey, filling the summer air with a sweet scent.
For water-wise garden beds in full sun, it’s tough to beat hardy ice plant, Delosperma cooperi, as a living mulch. This low-growing perennial forms a mat of succulent foliage topped with purple daisy-like flowers. Like alyssum, ice plant will bloom for most of the summer and into fall. Rock gardens are an especially good fit for ice plant where it will spread slowly but steadily for several years. Once established it requires little to no maintenance. Just be sure to plant in full sun and avoid overwatering.
Thyme, Thymus, is another favorite of mine and blurs the line between groundcover and living mulch (if there even is a difference). I use woolly thyme and creeping thyme in both my ornamental beds and around my flagstone pavers. This carpet-like perennial spreads at a very manageable rate of a couple inches every year and blooms every spring with tiny pink and purple flowers. Woolly thyme is exceptionally good for hot, sunny locations where irrigation is limited. As a bonus, thyme releases a pleasant minty aroma when stepped on.
If ornamental qualities are not a factor or if you’ll be using your living mulch as more of a cover crop, some of the most popular choices are:
• White Dutch clover
• Crimson clover
• Buckwheat
• Field pea
• Hairy vetch
• White mustard
• Lacy phacelia
• Strawberry clover
• Forage (tillage) radish
So hold the wood mulch, go ahead and crowd your garden, and capture that canopy! Living mulches offer a better solution for gardeners to protect and care for their soil while looking great at the same time.
