Archives  Groundcovers for Dry Shade

All spring, following dire warnings of drought, drought, drought!!!, we've had plenty of rain, rain, rain!!! 3" last night, in fact. But the fact remains that most of us have some dry shade at some point in the summer, and many of us have dry shade a good part of the year, under maples, beeches or birches, all water- and nutrient-depleting trees. With the changes in the earths' temperatures, and long-range predictions of reduced rainfall all over the country, water conservation is going to become as much a part of our lives here in Connecticut as it is for Californians. Since I always believe in planting the right plant in the appropriate site, (right plant, right place) I thought it might be a good idea to talk about some ground-covering plants that do well in a dry spot.

First, you need to determine what you need in a groundcover. If you're looking for a solid, weed-smothering, vigorous, monochromatic cover, you may want to look no further than Pachysandra terminalis, the Japanese Pachysandra. Although among plant snobs it has a bad reputation, it's really a very useful plant if you don't mind boring. Others that fall into this category include Vinca minor (Periwinkle), Hedera helix varieties (English Ivy) (on the invasive list in some parts of the country), Lamiastrum galeobdolon 'Variegata' (False Lamium), and Convallaria majalis (Lily of the Valley). A couple of others that are more on the order of garden thugs (rampant, invasive, plant-them-if-you-dare!) are the variegated goutweed, Aegopodium podagraria 'Variegatum', which spreads by underground stolons and should really be relegated to the most difficult areas, where there is no possibility of escape, and Fallopia japonica compacta. This one was formerly considered a Polygonum, which tells you a lot if you know anything about knotweeds. These are plants that should only be planted as a last resort. Once established they are very difficult to control, and nearly impossible to eradicate, because they spread underground and get into the root systems of other more desirable plants, so digging them leaves small pieces of root which proliferate even more, and spraying them with a non-selective herbicide will eliminate the surrounding desirables as well. One other that can fall into this category is the variegated Chameleon plant, Houttynia cordata 'Chameleon'. Although a pretty combination of green, pink, yellow and cream, it can be invasive in moist soils. Dry soils cause it to spread more slowly. But all of these are best relegated to containers, or perhaps the interior of a circular driveway in order to foil any chance of escape!

If, on the other hand, you are looking for a smaller-scale plant that spreads and covers the ground, albeit slowly, there are many wonderful plants that can make or enhance a garden. Some spread by runners (true groundcovers) and some spread by seed, expanding outward with self-sown progeny that eventually makes a substantial mass. All will serve to unify your garden by linking plants into compatible combinations, given thoughtful placement.

Among my evergreen choices, on top on the list of easy, reliable plants is Waldsteinia ternata, or Barren Strawberry. Low growing, dark green, and completely evergreen, it is happy in sun or shade, moist or dry, and is usually available in flats (as are Pachysandra and Vinca), so it can be planted on a larger scale at less expense than the larger pots usually entail. Yellow flowers in April and May are a bonus to its year-round attractiveness. My only complaint is that, aside from its spring bloom, it looks much the same ten months out of the year. I prefer plants that change from season to season, from new growth to their flowering period, then on to their fall color perhaps. But uniformity of appearance brings some comfort and reliability to the garden, so there is a place for this overall good plant.

Similar in effect to Waldsteinia, Chrysogonum virginianum and its cultivars are low growing, easy and versatile. It, too, is happy in sun or shade, moist or dry, but is not evergreen. Bright yellow flowers enhance it from late spring into summer, and sporadically thereafter, especially in the more clump-forming cultivar 'Pierre'. Its common names of Gold Star, or Green and Gold, describe it very well. It does not spread rapidly, but it is easy to divide and spread around to make a larger patch.

On a different order is Symphytum grandiflorum, an ornamental comfrey. A plant of rugged constitution, it grows a bit taller than the previous two, so might not be considered a groundcover, but in dry shade it only reaches 8-12", and spreads steadily and reliably to fill a substantial area. Its hairy foliage is not the most beautiful, but the cultivar 'Goldsmith' is a great improvement, its leaves splashed and edged in yellow. The overall effect is that of a hairy Pulmonaria, but its dangling bells on upright spikes are a pale cream-yellow, except for the cultivar 'Hidcote Blue', which has pale blue bells and is very attractive. I have grown all these varieties in the most inhospitable spots, which is where I developed my respect for them. Although not the most striking of my choices, they are indestructible plants that will survive the deepest drought.

Geranium macrorrhizum is another foot-tall, hairy leaved plant which spreads very nicely in sun or shade, moist or very dry. Its leaves are intensely fragrant, making it totally deer resistant - definitely a bonus in our woodlands! The species has magenta-pink flowers in early summer, but there are several cultivars with flowers in varying shades of pink to white. But it's the foliage that gives this plant its long-term appeal. Rounded, fuzzy leaves form a mound, which turns lovely shades of red in the fall, and is nearly evergreen around here. That, with its rugged constitution, makes it a plant for many different parts of the garden, even if magenta-pink isn't your favorite color!

Moving on to two much more refined plants, we come to Campanula poscharskyana and Veronica peduncularis 'Georgia Blue', both blue-flowered, spring blooming lovelies from the colder parts of Europe and Asia. The Campanula, called Serbian Bellflower, is one of the most vigorous of the creeping bellflowers, so is a good candidate for the woodland garden. Although it would appreciate more moisture, it is more permanent, albeit a bit slower, in dry soil. In May it is covered with starry lavender-blue flowers, smothering and splaying out from the attractive foliage. It is a great plant to place at the base of large stone steps, where the delicate flowers and foliage can show off so nicely

Veronica 'Georgia Blue' is from Soviet Georgia, not the southern U.S., so is nicely cold-hardy. Low mats of delicate foliage open bronzy-red in spring, gradually turning green as the weather warms, and are studded with incredible true-blue upfacing flowers with a pure white eye. A complete charmer, even if it didn't spread slowly and reliably under maples! It doesn't move fast, but it's a steady creeper, great for planting with spring-blooming bulbs.

No discussion of plants for dry shade would be complete without a mention of the Epimediums, or barrenworts (where do they come up with these "common" names?). There are many varieties, most from the Mediterranean to China, Japan and Korea, with more being discovered every year. All are superb, slow-spreading groundcovers for shady areas, with beautiful heart-shaped foliage and delicate columbine-like flowers on wiry stems in spring, ranging in color from white to yellow to all shades of pink to red. But their main attribute is their foliage, which can open bronzy, later turning green in the warmer months, and sometimes back to fine fall colors, although some are evergreen. Most are considered clumpers, but the forms E. x perralchicum 'Frohnleiten' and x rubrum spread quite a bit faster. Rubrum is considered to have the best foliage of the groundcover types, although 'Frohnleiten' is evergreen. But any woodland garden has room for all of them, and you can pick your favorites. Make sure you trim back any winter foliage in early spring before they start to grow, or you'll find yourself cutting off the flowers! As with most of these plants, they will spread faster if the soil is moist, but just move a bit slower if you don't irrigate.

The last category of shady groundcovers I would like to consider are clumping plants that like to self-sow, thereby increasing their coverage. Among these, I would never be without Alchemilla mollis (Lady's Mantle), Brunnera macrophylla (Perennial Forget-me-nots), and Euphorbia amygdaloides 'Purpurea' and robbiae. All are superb foliage plants that would have a place in my garden even without blooms. The blossoms are an added bonus that make me feel fortunate indeed. Alchemilla has gorgeous leaves, gray-green and folded like a fan in spring, and they have the amazing ability to catch the dew in the early morning, which glistens and glitters in the morning sun. From June to August, sprays of chartreuse blossoms, great for cutting, splay from the attractive clumps. It is a wonderful blending plant, for everything goes with chartreuse, and it seems to enhance the colors of surrounding plants. The fact that it self-sows turns it into a ground-cover, and it looks superb combined with larger leaved Hostas, or spiky plants like Siberian Iris. It is happy in sun or shade, and as usual will spread faster in moist soil, but is perfectly happy in dry.

Brunnera macrophylla has always been recommended for shady spots, because the dark green leaves grow larger and more beautiful in deeper shade. But on our hillside by the driveway, it has grown happily in full sun and dry soil since the large Chamaecyparis that shaded it was taken out. So it appears to be supremely adaptable, happy to self-sow wherever you put it. True-blue flowers in May and June appear on 15" stems and give the effect of forget-me-nots. Two new cultivars show a lot of promise, but these will not tolerate sun on the big leaves. 'Jack Frost' is the best plant I put in my garden last year, with stunning silver overlaying the leaves. A seedling which appeared beside it is also silver! Imagine a swath of silver and blue in spring in your shady woodland. Heaven! Another cultivar, the variegated form, has a gorgeous wide border of creamy white. Unfortunately this one does not retain its variegation when it self-sows. I guess you can't have everything!

My last two plants are four-season perennials, equally stunning from spring all the way through winter. The Euphorbias have become very chic in the past few years, with their chartreuse bracts and deer-proof foliage, and these two are great all-around plants. Euphorbia amygdaloides 'Purpurea' has an impossible name, but is worth growing in spite of it. Commonly known as Purple Wood Spurge, it has attractive mounds of greenish foliage and long stems which carry the chartreuse bracts in spring. When the cold weather hits in the fall, the foliage turns a deep purple-red, and is evergreen for us. When it gets untidy, I simply whack it back with my clippers no matter when it starts to bug me. It self-sows nicely, and some wonderful combinations can be made with it and perhaps some yellow-twigged dogwood for the winter garden. The species robbiae has larger foliage which doesn't turn such a gorgeous shade of purple in the winter, but it is so happy in dry shade that some people find it a nuisance. But it is easy enough to control, and it adds another dimension to our shady, dry border.

There are many more plants that will tolerate dry shade, such as the Lamiums, but I think I will save them for my next discussion, Plants for Moist Shade. Or is that a ridiculous idea? In dry, rocky Connecticut, is there a need for such a consideration?

Maples, beeches or birches are all water- and nutrient-depleting trees, because they are very shallow rooted. Improving the soil, by tilling in loads of compost and organic matter, bone meal, lime and manure, works for a few years because you cut the surface roots when you turn the soil over. But the trees that have created the initial problem jump at the chance to invade your much-improved soil, so you end up with the same situation after just two or three years. Trees that have a deeper root system, or are tap-rooted, give groundcovering plants a better chance because there isn't as much competition. Oaks and hickories are great trees to grow shade plants under, because their roots are much deeper. Tap-rooted trees such as tulip and Nyssa (Black Tupelo), which are native to this area, are also great, but if you're looking to plant one in your garden, they are not as available in the nurseries because they are difficult to transplant from the field.

Pines, hemlocks, and other coniferous plants would be fine to plant under except for two specific problems. First, their needles are very acidic, so they make the soil even more acid than it normally is in this part of the country. This can be dealt with using lime to neutralize. But the second problem is unsolvable. They cast shade for twelve months out of the year, unlike deciduous plants, which allow strong spring sun, so many plants are not able to manufacture enough chlorophyll to subsist beneath them. If you've ever taken a walk in a mature pine or hemlock forest, you'll see what I mean. So to grow anything under them, you really need to pick a spot that gets some filtered light, and neutralize the acidity

Being the lazy gardener that I am, I have picked some plants for you that don't require a lot of soil preparation, and will grow happily, if a bit more slowly, under the dreaded maples, birches and beeches. If you don't have any of the dreaded trio, and you love to get sweaty double-digging the soil for the ultimate garden, these plants will thrive and multiply three times as quickly in your ideal conditions.

On a smaller scale, spreading much slower, are Campanula portenschlagiana and C. rotundifolia. C. portenschlagiana used to be called C. muralis, a much simpler name meaning "of the wall". It, and C. rotundifolia, love to creep between crevices, but only a rock-gardener would call them "ground covers." The deep blue bells of C. portenschlagiana splay out from the beautiful, semi-evergreen foliage in late May, and it is happy growing even in deep shade if the drainage is good. C. rotundifolia likes the same conditions, but has small blue or white bells which dance on 6-12" stems for a long time in summer. It, too, is a crevice-lover, and nothing is more charming than seeing it growing between paving stones or in a retaining wall.