Tiarella (Tiarella cordifolia) is a pretty spring-blooming perennial for shady borders, under shrubs and for woodland settings where an attractive groundcover is desired. If you like heuchera, tiarella is like a first cousin, very similar yet with its own charm. Most tiarella cultivars on the market today are nativars; that is, gently improved versions of our native foam flower. As a result they are hardy, undemanding, and valued for both very charming flowers and attractive, well-marked foliage.
The taxonomy of tiarella is complex and not for the faint of heart to disentangle; I’m not about to try it here. Recent changes to classification and cross-breeding with heucheras adds to the chaos. Suffice it to say that the species Tiarella cordifolia or Allegheny Foamflower, is native to North America. Emanating from this primary species are a handful of subspecies, based on geography and whether or not the plant puts forth stolons. Stolons are runners which form new litle plantlets at the ends, like a strawberry plant, and can spread to form large colonies.
Native forms may or may not have stolons; the straight species cordifolia does have stolons, and in the wild can carpet the ground in swaths.
However, most tiarella nativars and hybrids sold in the trade are clump-forming instead and do not have stolons, making them appropriate for any size garden. They have a habit much like heuchera, staying in tidy clumps.
A popular clumping variety is tiarella cordifolia wherryi or Wherryi’s foam flower (named for a botanist named Wherryi). This is the parent plant of most commercially offered tiarella cultivars. That is all you really need to know about tiarella’s taxonomy unless you’re a total plant geek, in which case, try Wikipedia!
Tiarella Cultivars
So what are some popular choices at nurseries, and what do they look like?
Most tiarellas have sharply divided foliage sporting burgundy veins, either pronounced or subtle, on a rich green background. A mature clump is about fourteen inches across and eight to ten inches tall (not counting the flower spikes). In spring, a dozen or more bare stems rise above the foliage, each topped with a cluster of small starry flowers. Some form pointed racemes, others are fat bottlebrushes. A few have pink buds and pedicels, but all open to white or creamy stars. Massed, the flowers seem to float in a cloud above the leaves, creating an airy feminine effect.
Sugar and Spice – A rosy-budded tiarella with arrowhead racemes and orange-tipped stamens. Foliage is lime-green with prominent burgundy veining. A prolific bloomer with 15″ flower spikes. I love this variety.
Pink Torch – Similar to Sugar and Spice but with looser, somewhat smaller bottlebrush infloresences. A nice informal look for woodlands. Really sweet.
Black Snowflake – This tiarella has extra long racemes and deeply palmate leaves with black centers, very dramatic, yet elegant looking.
New Moon Motley – A new hybrid with both a stolon form and a clumping form. The nearly iridescent ivy-shaped leaves more closely resemble the wild cordifolia, a giveaway that it might be stolon-forming. Unusual bicolor foliage! An intriguing groundcover choice for sure. The flowers are typical, but you buy this one for its leaves.
Others include Oakleaf, Brandywine, Running Tapestry and more.
Tiarella has a long bloom period about six weeks starting mid-spring. After the flowers fade, the foliage remains nice as long as the soil remains moist. If conditions are too dry, it tends to go dormant but will usually reappear the following spring. Some cultivars even turn red in fall.
Tiarellas prefer shade or mostly shade and moist woodsy humus with adequate drainage. They cannot tolerate full sun nor wet feet in winter. I lost several Sugar and Spice to a combination of clay soil and a very wet winter. But I’ll be replacing them, as I really enjoy their perky accent.
Tiarella or Heuchera?
At first glance, clumps of tiarella out of flower can be easy to mistake for heuchera, which is an entirely different genus. One way to tell them apart is heuchera leaves are usually larger with more bluntly-divided leaves, and it prefers sun or part sun and drier conditons than tiarella. But there is another complicating factor making identification difficult.
Somehow given the topical similarities, I suppose it was only natural that breeders decided to cross these two to form Heucherellas. (This is called an intergeneric cross, according to the Wellfield Botanic Gardens website). As you might expect, heucherellas fall somewhere between the parents in habit and appearance, but tolerate a wider range of conditions. In turn their hybrid offspring are named, what else– Cinderella!
Cinderellas are true hybrids, with the excellent disease resistance of tiarella and bolder coloration and longer bloom times of heuchera. Cinderellas tolerate more sun and less water too. Some have foliage that lasts well into winter as long as the plant is covered lightly with pine boughs or a lightweight mulch.
I haven’t tried growing Cinderellas yet, but I’ll be on the lookout for them. Judging by the photo, Pink Fizz is very attractive, with deeper pink flowers and black-veined leaves. Now if only I can find it for sale!
Telling these apart in the field can be challenging but not all that important for the home gardener. The point is, enjoy them and don’t worry too much about what’s what. With tiarellas for spring, heucherellas and Cinderellas for summer, and heucheras all summer into fall, it’s now possible to bridge and overlap the bloom periods of all three.
Give tiarella or Cinderella a try, won’t you?
