Having grown hardy flowers for more than 25 years, I'm not sure how we missed prairie mallows (Sidalcea) until recently. Slender and upright, the prairie mallow is not extravagantly showy, but it's pretty enough in sunny beds. Like most of the family, it's generous with bloom, flowering for weeks in midsummer. The shallow saucer-shaped flowers, smaller than those of musk mallows, array tapering 60- to 100-centi-metre stems, which are useful for cutting. Prairie mallows look a bit wild, and so they are. Gardeners interested in native plants should know that two species, the white – flowered S. candida and mauve – pink S. malviflora (both Zone 5), are native to the western regions of North America. The latter has given rise to several hybrids: 'Rose Queen', more magenta than rose, can be raised from seed; 'Elsie Heugh', with fringed, pale pink flowers, is pretty when massed; 'Brilliant' is darker purple-rose. All put on a fine show grown behind (or through) pink baby's breath (Gypsophila 'Rosy Veil'), with the silver leaves of lambs' ears or artemisia nearby. Steel-blue sea hollies and white shasta daisies are suitable companions; all three are about the same height. Grow one prairie mallow and before long you're sure to have a few more from seed.
Taller, more robust and wilder-looking than the prairie mallow, the striped mallow (Malva sylvestris mauritanica, Zone 5) can soar to 150 centimetres, opening rose-purple flowers prominently veined with maroon, like loose-petalled hollyhocks, from July to October. 'Zebrina' is lighter in tone, while 'Mystic Merlin' is darker, but both exhibit the bold stripes that give them their common name. Very short-lived, sometimes leaning toward annual or biennial status, this informal mallow can be counted on to come up afresh from its own seeds. If you get too many, pull them up. An old European cottage-garden plant, the striped mallow is not for gardeners who want an orderly, everything-in-its-place kind of garden; this plant belongs where there is space to fill and lax habit and waywardness are seen as virtues.
Two Lavatera round out the mallow family. The tree mallow (L. olbia) looks more like a small shrub than a perennial, but comes back from its base each spring – with any luck. Said to belong in Zones 7 to 9, it is not a sure bet in most of Canada. That said, our clumps have survived in our Zone 4 garden for three years, a fair run for any mallow. Apparently all the rage in Europe, tree mallows are just beginning to catch on in Canadian gardens, thanks in part to the lovely L. 'Barnsley' cultivar, with rose- centred white blooms that fade to light pink. Said to be a bit hardier (Zone 5 with winter protection), this tall plant – up to two metres – grows against the grey stone wall of our garden shed, adding its hibiscus-like form and pleasant colour at the back of the bed that includes pink bee balm, deep rose speedwell and lavender. By August everything is tangled up, as the tree mallows incline their branches through the rest. Bamboo canes and several tiers of string help keep this willowy mallow upright and where it belongs.
The wild tree mallow blooms, naturally enough, mallow pink-a purple-tinged shade. Occasionally, 'Barnsley' will return to its roots and send up stems of plain pink flowers in its second or third year. Cutting away such stems is recommended, but I quite like them. L. 'Candy Floss' is supposed to be solid pink. Whatever the colour, tree mallows are among the longest-blooming perennials, starting in early July and often opening fresh flowers at Thanksgiving.