Perennial Flowers That Like Moist Places

by Henry Homeyer

CORNISH FLAT, N.H. – I’m lucky. Even though my property is relatively small, just over 2 acres, I have all the possible growing conditions a plant could want: wet, dry, sunny and shady. And I’m willing to try almost anything that will survive 20 or 25 below in winter.

That said, there are some challenges. There is a small stream behind my house, and my water table is high: dig down a couple of feet in spring, and much of my land will have standing water. It stays a bit wet, summer and winter. But here are some wonderful plants that love moisture.

Each spring I write about my Japanese or candelabra primroses (Primula japonica). They bloom for six weeks or so in magenta, pink and white with a yellow eye. They love moisture. During their “show”, I try to get friends who are gardeners to come visit, and we sit in the late afternoon, watching their display under a group of ancient wild apple trees.

This spring I added another species of primrose, Primula sieboldii, which I got at E.C. Brown Nursery in Thetford, Vt. I was told that, like the Japanese primrose, it seeds freely and spreads easily. It is an ephemeral, meaning that after blossoming the leaves disappear until next spring. It forms clumps up to 12 inches across, and blooms in pure white, blue, purple, and pinkish. I can’t wait to see if I get any new plants and colors next spring.

This year I have some new plants in my primrose garden given to me by a new friend and fellow garden writer, Judith Irven of Goshen,Vt. It is called false hydrangea (Dienanathe spp.) and comes in two colors, blue (D. caerulea) and creamy white and (D. bifida). I planted them in the primrose garden last fall, and both survived and thrived. They have been blooming now for a few weeks.

I had never heard of or seen the false hydrangea until visiting Judith last fall. The leaves are a bit like some hydrangeas, but the flowers are not. But these beauties are quite an addition to my moist shade garden.

Another genus (botanical category) of plants that like moist soil are the burnets (Sanguisorba spp.). I have several species, starting with our native wildflower, Canadian burnet (Sanguisorba canadensis). This is a fall bloomer that produces flower stems four to six feet tall with white bottlebrush flowers. It starts to bloom in late August, and some years bloom into November. I have it growing in a marshy area near my stream.

I have at least four other kinds of burnet, starting with a little one with variegated green and white leaves and deep maroon flowers (Sanguisorba officinalis var. microcephala ‘Little Angel’). I have others that grow two feet tall, and one that is four feet tall, both probably varieties of S. officianalis. The taller ones I tie up with stakes and strings by mid-July to keep them from flopping. A single plant will grow to be a big clump, taking a space four feet wide.

I am still looking for a burnet called ‘Lilac Squirrel’, a variety of S. hakusenensis. The name, and blossoms that resemble pink boas, are too outrageous not to want one. If you have one, please email a photo. Like all burnets, it likes moist soil and sunshine, from what I have read. It is hardy to Zone 5 – minus 20 in winter.

Another interesting genus is Persicaria, the fleece flowers. I have two species, P. polymorha or giant fleece flower and red bistort or mountain fleece (S. amplexicaulis). Giant fleeceflower makes a clump six to eight-feet tall and wide, with white blossoms a bit like astillbe blossoms – on steroids. The stems are an inch wide or more, but hollow like Japanese knotweed. The nice thing about it is that the flowers look good even after they have gone by, so two months of beauty is a given. Moving one is hard work, so plant it where you have plenty of space for it.

I have mountain fleece under the apple trees in my primrose garden, and the red bottle-brush flowers are just coming into bloom on three- to four-foot stems. The leaves are large, pointy and heart-shaped. Like its cousin, the bloom time is long: from now through much of the fall.

There are plenty of wildflowers that do well in moist shade. Prime among them are Jack-in-the-pulpit, red baneberry, trillium, and ramps. I grew up in Connecticut where there was skunk cabbage growing by our stream, and I bought a small clump some 25 years ago at The Garden in the Woods in Framingham, Mass. What a difference a couple of hundred miles makes. This early-spring bloomer has only recently achieved full size! I attribute that to the climate.

Many plants that grow well in ordinary garden soil will thrive in moist soil, too. I have Black-Eyed Susans (Rudbeckia spp.) that love my moist, sunny gardens but would be equally at home in drier soil. My favorite is Henry Eiler, one that blooms late and has very distinctive blossoms with the petals unnaturally far apart.

If you want to grow a shade-loving plant in a sunny location, you will have a better chance of success if the soil is also moist. Even then, not all succeed. But if you have space, and a willingness to experiment, your flowers may surprise you.