Tiarella trifoliata, commonly called “foamflower,” is a lovely woodland perennial within the Western hemlock/Douglas-fir plant community of the Pacific Northwest. Besides having beautiful, soft green leaves that are often divided into 3 leaflets, its sprays of delicate flowers—of the palest pink—bloom on leafy stems for an amazingly long time: from May to as late as September. Really!
How it grows
This charming plant can be found in damp, shady forests, and near streams. It has rhizomes but doesn’t spread like typical ground cover plants; in fact, you’re more likely to find it self sowing than spreading speedily underground. There are three varieties: Tiarella trifoliata var. trifoliata, the one you’re most likely to find for sale, is found mainly west of the Cascades as well as in southern Alaska and British Columbia, at low to middle elevations. T. trifoliata var. unifoliata occurs on both sides of the Cascades, west to Montana, and in B.C. and northern California, typically at higher elevations; it has more deeply lobed leaves. T. trifoliata var. laciniata, has a small range—only a few counties in Washington and Oregon and parts of B.C.; its leaves are maplelike and shallowly lobed. The other North American foamflower is T. cordifolia, native to the eastern U.S.
Foamflower’s clusters of tiny blossoms provide pollen and nectar for native bees and syrphid (flower) flies. Seeds are eaten by birds such as sparrows. Foliage provides cover for very small creatures and protects the soil.
Try it at home
Maturing to about a foot tall and wide, it’s best grown en masse in the shade (or partial shade) of conifers where the soil is well-drained but naturally rich (or has been amended with organic matter, like compost), as well as along shaded pathways or near ponds and streams. Grow it with associated species such as Douglas-fir, western hemlock, western red-cedar, vine maple, serviceberry, oceanspray, thimbleberry, sword fern, salal, Cascade Oregon grape, inside-out flower, oxalis, and many others. Plant this gem in the fall for best results. If it’s not grown in a moist area, keep it happy with supplemental water during dry periods and it will self sow, but only in the most polite way.