In the Garden November 2015

By Rhiannon Allen

I personally think blank spaces in the garden help set off ornamental plants. By “blank,” I mean non-green areas that show soil, mulch, rock, gravel or sand. However, some gardeners prefer the total coverage look, abhorring earth tones of brown and gray.

One solution for people with such preferences is to jam-pack their gardens with ornamental plants. Another approach utilizes groundcovers – short, ground-hugging lush plants that form a blanket underneath trees, shrubs and taller ornamentals.

I admit groundcovers have their advantages. A good groundcover will save you time by choking out weeds. It can also provide visual interest by filling in bald spots or setting off the visual beauty of a taller plant. The latter attribute works particularly well when the groundcover’s foliage contrasts nicely with the color or shape of the taller plant.

Unfortunately, many groundcovers can be problematic. Invasive by design, they can choke small (and sometimes even large), more desirable plants. They can escape into the wild, your neighbor’s yard or your lawn. Some provide cover for pests such as slugs and rats.

The wall of shame for invasive groundcovers features English ivy, yellow archangel, goutweed and periwinkle. None of these is quite as bad as kudzu, the Japanese vine introduced to North America as a roadside stabilizer, which has since swallowed barns, cars, and anything slower than a slug. But all groundcovers, while pretty in your own garden, have the potential to take over Point Roberts if left uncontained.

Fortunately, there are relatively well-behaved alternatives, plants that can green up a boring, dingy corner but are easy to control. Sweet woodruff (Gallium odoratum), an attractive relative of our native stickweed or bedstraw (Gallium oreganum), is a great deer-resistant groundcover for part-shade or shady areas, provided you can moisten the soil during summer droughts.

This plant has delicate foliage and dainty white flowers. As a bonus, the leaves give off a pleasant aroma when crushed, hence its former use to deodorize mattresses and scent linens. If it likes its growing conditions, sweet woodruff will spread its roots slowly into adjacent areas. Given its attractive appearance, this rarely causes aesthetic problems. And if it does offend, the plant is easily pulled up or mowed.

While sweet woodruff might be the subtle supporting actress of shady spots, one of my favorites for dry, sunny areas is our native beach strawberry (Fragaria chiloensis). It will flourish even in dry, poor, sandy soil. This very compact, low perennial has glossy green leaves, sports pretty white flowers in late spring and often turns red in winter.

I’ve read that the fruit is tasty, but I’ve never beaten our garden fauna to the prize. Like culinary strawberries, beach strawberry spreads by sending out horizontal stolons that form new plants when they touch soil.

To control spread, cut the stolon close to the mother plant before it roots. Like sweet woodruff, undesirable offshoots can be easily hand-pulled or mowed for control.

Sometimes you need a groundcover even more compact than these two, or that has leaves that are not green. New Zealand brass buttons (leptinella squalida) might be the groundcover for those occasions. This plant forms a dense mat of foliage that looks like tiny bronze or purplish ferns. Like sweet woodruff, it needs a bit of water during droughts, but is otherwise quite tolerant of growing conditions.

I heard many years ago that this plant had been placed on Whatcom County Noxious Weed Control Board’s watch list, which meant that commissioners were wondering whether the plant could prove to be invasive or harmful. However, the plant has never actually appeared on the weed list, so I assume that it has been given the all-clear.

I’ve grown this plant in a number of places, and found it to be a slow but persistent spreader in moist part shade but less rambunctious under other conditions. Like sweet woodruff, it spreads via its roots, but is more resistant to yanking. Like sweet woodruff, it has grown into my lawn at one place. Given that some people use this plant as a lawn substitute, this might even be considered a positive development.

In any case, it certainly is as attractive as grass, and a lot more interesting. I love taking a close look at its intricate ferny leaves, even if I have to get down on my knees to fully appreciate their delicateness.

Of course, these are just my personal favorites. Others gardeners might be partial to pachysandra, kinnikinnick, wild ginger, blue star creeper, blue Pacific juniper or bunchberry. The selection is pretty broad, so I’m sure everyone can find a well-behaved groundcover that fits their conditions and personal tastes.