Native Groundcover Plants

The case against annual mulching

The standard American planting is specimens spaced apart in a field of bark mulch, refreshed every spring. It works, and it costs money and a weekend every year forever, and it supports nothing.

A continuous layer of low plants does what the mulch does: shades the soil, suppresses weed germination, moderates temperature, and slows erosion. It also holds moisture, feeds insects, and gets denser rather than thinner over time.

In natural plant communities there is no bare ground. Something covers every inch, and that is the model worth copying.

Match the plant to the site, not to a list

Groundcovers are the plants most often installed in the wrong conditions, because people treat them as interchangeable.

For dry shade under trees, Pennsylvania sedge, wild ginger, and Christmas fern. For moist shade, foamflower and wild geranium. For a hot dry sunny slope, creeping phlox and the low form of fragrant sumac. For sandy, cold, exposed ground, bearberry. For a large sunny area that needs to look like a meadow rather than a carpet, prairie dropseed or blue grama.

A groundcover in the wrong conditions stays thin and patchy for years, which looks worse than mulch.

Getting to closure

The first two or three years are the whole difficulty. Until plants knit together, the open ground between them grows weeds, and a groundcover planting abandoned during that period fails.

Spacing is a straight tradeoff. Plants at twelve inches close in two years and cost twice what plants at eighteen inches do, which take three or four. Decide which you would rather spend.

Mulch lightly between the plants for the first season only, then let them take over. Weed regularly during establishment, and be prepared to keep at it for about two seasons.

Water through the first year, and choose an appropriate species rather than trying to make a difficult one work.

The invasive alternatives, and why to skip them

English ivy, periwinkle, Japanese pachysandra, and wintercreeper are the four groundcovers most commonly planted in shade, and all four escape into natural areas. English ivy climbs and kills mature trees. Periwinkle forms mats that exclude woodland wildflowers entirely.

The native replacements do the same job at the same scale. They are slower to establish, which is the honest tradeoff, and they do not turn up in the woods behind the neighborhood ten years later.

Sources: Lady Bird Johnson Wildflower Center, University of Texas at Austin (species profiles and cultural requirements); Mt. Cuba Center (groundcover trials on rate of spread and coverage); US National Park Service and state invasive plant councils (invasive groundcover impacts in eastern forests).