I’ve been looking back at some of the garden pictures I’ve taken over the past month or so, and in particular at the plants and shrubs that bloom after the spring glut, but before main season summer-flowering species take over during the hottest part of the year. These are useful “bridging plants” that prevent flower beds from looking empty as one season gives way to another.
In fact, they’re so useful for maintaining a steady stream of flowers that I intend to bulk up my stocks for next year, beginning with Mayapples:
Taking over nicely from springtime hepaticas, trilliums and Jack-in-the-pulpits are our native Mayapples (Podophyllum peltatum, Zone 4) which produce fragrant white blooms underneath their leafy green “umbrellas.” I grow them in full shade in moist, humus-rich soil where they spend the summer with various ferns and monkshoods; dryer soils will result in plants going dormant in midsummer. Spreading slowly via underground rhizomes (or stems), any unwanted plants are easy to pull out.
Another useful North American native is blue camassia (Camassia leichtlinii ssp. suksdorfii, Zone 4). Bulbs of blue camassia are purchased and planted in the autumn at the same time as daffodils and tulips, and slowly spread to form a handsome clump like this one:
Until they’ve finished blooming, camassias require a full sun location in moist, rich garden soil, but—like so many bulbs—after flowering, they prefer to dry out and have a good summer “bake.” Growing about 60 centimetres tall, their foliage should be left to mature naturally (never braid or tie leaves up). I place summer-blooming Campanula and Salvia cultivars in front of my camassia clumps to hide their yellowing leaves.
White-flowered camassia (C. l. ssp. leichtlinii) bulbs are often sold right next to the blue ones, but I avoid these. They begin to bloom two weeks after the blues have finished, and their sparse flowers are a rather nondescript cream colour—not white.
Tree peonies (Paeonia ×lemoinei, P. lutea and P. suffruticosa cvs.) are often considered difficult to grow, perhaps because after transplanting, some varieties may take a couple of years to settle down and start blooming. The main trick is to ensure that the graft union (the area where the roots meet the shoots) is 10 to 15 centimetres below the soil surface.
Blooming two to three weeks before garden peonies (P. lactiflora cvs.), tree peonies have larger flowers—including yellow—don’t require staking, and most are hardy to Zone 4. All you need is good garden soil, a sun to part-shade location and a bit of patience.
After the early, fragrant viburnums and lilacs have finished blooming, there isn’t a lot to look forward to as far as scented flowering shrubs are concerned. And while it’s true that hydrangeas, spireas and weigelas bloom in summer, few of them have a noticeably sweet fragrance.
That’s where fragrant (or Korean) abelia comes in: Abelia mosanensis (Zone 4) blooms about a month after the Preston (late) lilacs have finished, and their scent is as good as—some say better—than the best French lilac cultivars.
Growing 150 centimetres high by 100 cms wide, Korean abelia sets flower buds in summer on new wood that open the following year in clusters of heavenly-scented pinkish white blooms. Content in average garden soil in a sun to part-shade location, shrubs should be pruned immediately after flowering to emphasize their vase-shaped habit.
About eight years ago, Dr. Tim Wood of Spring Meadow Nursery (Michigan) introduced a strain of Korean abelia (sourced in Latvia, of all places!) under the Proven Winners banner. Widely available in the U.S., it’s difficult to find in Canada which is odd, given its hardiness (probably to Zone 3). In addition to its ethereally fragrant flowers, the foliage of Korean abelia turns a brilliant orange-red in autumn, so we can only hope that it will soon appear in greater numbers on this side of the border.