Part 1 – The Shade Garden.
In northeastern North America (where I live), Mother Nature likes to constantly change things up. Few of our native plants stay flowering for more than a month or two, and some for only a few weeks. But, in nature, bees and other insects cannot survive for long periods without flowers, so there ARE plants blooming from early spring right through till snow covers them. Unfortunately, the bees (and we) need to search them out.
In the spring, our earliest blooming plants tend to grow in forests as spring ephemerals – they open before the trees leaf out, then disappear once the tree canopy closes in. Plants like Hepaticas (Hepatica americana and H. acutiloba), Jack in the Pulpit (Arisaema triphyllum), White and Red Trilliums (Trillium grandiflorum and T. erectum), Bloodroot (Sanguinaria canadensis) and Trout Lily (Erythronium americanum) all provide a nice, early splash of colour. By mid-May, though, most of these plants have finished blooming. If you have a shady yard, the rest of the season can be pretty bleak – one reason, I suppose, that non-native hostas are so popular. (Did you know that in Japan, where hostas are native, the young spring shoots are collected and eaten like asparagus?)
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In the fall, a few shade tolerant plants will blossom, taking advantage of the falling leaves that allow more light to reach the ground. These include Zig-zag Goldenrod (Solidago flexicaulis), Large Leaf Aster (Eurybia macrophylla), Upland White Goldenrod (Solidago ptarmicoides) and Blue Stemmed Goldenrod (Solidago caesia), which all do well in dry shade. If you have more moisture, you can add such things as White Snakeroot (Ageratina altissima), Sweet Joe Pyeweed (Eutrochium purpureum), Obedient Plant (Physostegia virginiana) or Blue Wood Aster (Symphiotrichum cordifolium) for a little more variety.
For shade gardens, ferns are a great choice to fill in the blank period between spring and fall. If you have some moisture, you can grow many different fern species, but if your shade is dry (the worst kind, from a gardening perspective), you are much more restricted. But there are some ferns that will grow in dry shade, though maybe not without a little help in very dry years. These include Lady Fern (Athyrium filix-femina), Christmas Fern (Polystichum acrostichoides), Eastern Wood Fern (Dryopteris marginalis) and Hay-scented Fern (Dennstaedtia punctilobula). Both the wood fern and the Christmas fern are evergreen, so they will provide that splash of green in the garden that we long for as the snow starts to melt. Hay scented fern can be quite aggressive, and is really only suitable if you have lots of space that needs filling, and don’t mind managing its spread once in a while. But even Ostrich Fern (Matteuccia struthiopteris) – the one we get edible fiddleheads from – does well in my dry full-shade garden under large Sugar Maples. In dry years they will go dormant in mid-summer if I don’t water them once in a while, but they always come back. They positively thrive in moist shade. Be forewarned, though, they will eventually spread beyond the garden setting – however, they’re easy to dig out to sell or give away to friends and family.
Most folks don’t realize it, but we do have some plants that can provide colour in the shade through the summer, if the shade isn’t too dense (think Tulip Tree, Kentucky Coffee Tree or a younger Sugar Maple or even a young Black Walnut – but not Norway Maple). Harebell (Campanula rotundifolia) will tolerate dry shade, starts to bloom in June and will go all the way through to the end of September. Evening primrose (Oenothera biennis) is another long-flowering plant that blooms from June to the end of August (sometimes even later) and tolerates light, dry shade. And then there are shorter blooming plants that that can stagger the colour throughout the summer.
During the first half of the summer, Canada Anemone (Anemonastrum canadense), Wild Geranium (Geranium maculatum), False Solomon’s Seal (Maianthemum racemosum) Hairy Beardtongue (Penstemon hirstutis) and even Virginia Spiderwort (Tradescantia virginiana) will do well in dry shade. (The more northerly Ohio Spiderwort (T. ohiensis) prefers a bit more light and moisture than its southern cousin, so if you have medium to moist light shade, it will do just fine). We also have several species of violets that will tolerate medium to dry soils in light shade – some will even tolerate fairly heavy shade. And violets come in a nice range of colours, too. Canada Violet (Viola canadensis) is white, Downy Yellow Violet (V. pubescens) is lemon yellow, and the very interesting looking Long-spurred violet (V. rostrata) is a pink or pale purple.
In my southwestern Ontario garden, Wood Poppy (Stylophorum diphyllum), which most books will tell you likes full sun to part shade and moist conditions, thrives under my large sugar maples in dry soil and starts flowering in early May. In a good year, it can still be flowering well into the summer, though normally it just lasts for three or four weeks. And contrary to everything I’ve ever know about Blue Lobelia (Lobelia siphilitica), I have volunteers coming up in that same dry shade year after year.
If you’re lucky enough to have moist shade, there are lots of options available for colour all season long. Most of the plants already listed will tolerate moister soils (with the exception, perhaps, of Blue Stemmed and Zig-zag Goldenrods). In mid-summer, if it’s not TOO dry, Black Cohosh (Actaea racemosa) will send up its tall white spires in shady settings in June and July, along with Poke Milkweed (Asclepias exaltata). And if the shade is not too heavy, even Wild Columbine (Aquilegia canadensis) will flower from May to July and Anise Hyssop (Agastache foeniculum) from end of June to the middle of September. Virginia Bluebells (Mertensia virginica) are an early bloomer that makes a great companion plant with Ostrich Ferns, sending up their pink and blue flowers just as the fens are starting to unfold. And the brilliant red of Cardinal Flower (Lobelia cardinalis) will light up the light-shade garden in average to moist soils in July and August.
So with a little careful planning, you can have continuous colour in most shade gardens. The list of suggestions provided here is by no means exhaustive – there are lots more plants that will grow in shade, but this will give you a start in your planning.
Next time: Continuous colour in the rest of the yard.