dry shade

Radical Ruminations

Poised on the brink of another spring — and retirement! — I’m considering the options for renovating my garden. As I’ve lamented in a number of posts, the back garden is dominated by two mature Norway maples and a Tree of Heaven (Ailanthus). The entire space (about 30 x 50 feet) has been infiltrated with a solid mat of maple roots, which makes it difficult to grow any but the toughest plants, especially in soil that is mostly sand, and in a summer-dry climate.

 

The Norway maples. Imagine the roots!

The Norway maples. Imagine the roots!

 

The Tree of Heaven. The huge red maple on the right is on a neighbour's property.

The Tree of Heaven. The huge red maple on the right is on a neighbour’s property.

More than once, I have decided to have the trees removed — all three of them. That would open up the sky above the garden and get rid of the roots (eventually). I could grow plants well that barely perform now — peonies, roses, delphiniums, irises! The water lilies in the pond would actually bloom!

Then I think about the disruption. A vigorous climbing rose (white flowers with a pink tinge, very double, in May and June) has slung itself over the lowest limbs of one of the maples. It would have either to be cut down or provided with some other support. Men with size 12 feet would tromp all over the place and there would be all that wood to deal with.

Climbing rose in maple

Climbing rose in maple

Then there’s the expense. Tree removal is not cheap, and I am about to swap money for time.

So I come around to leaving the trees alone and working on the plantings that share space with them. Here, I have a few options:

  1. Remake the Beds. This means digging up the plants I value and stashing them somewhere while I dig out the surface roots and amend the soil with compost and other goodies. Then replant, adding new plants suitable for dry shade. Advantage: the plants will grow quite well for a while. Disadvantages: Back-breaking labour, and the effect would be temporary; in a few years the tree roots will re-grow.
  2. Adjust the Beds. Identify attractive (to me) plants that actually thrive under the present conditions. Get rid of all the sad sacks and weedy specimens and add more of these superstars — mainly hellebores and ferns with spring-blooming bulbs. Fussier things (delphiniums and lilies) could be grown in pots and parachuted in for blobs of colour in season.
  3. Keep the Status Quo. The trouble is, in gardens, there’s no such thing as status quo. Succession kicks in, some plants die, others prosper and in a few years it’s all rose campion, purple toadflax and feverfew jostling around the original hellebores. And yet, even a mess like that can look amazingly good in the slanting light of a summer evening, as long as the bed is defined by edging and trimming.

In the short term, i.e., the next year or two, I think I’ll go with a combination of options 1 and 2. The first thing will be to make the 18-inch tall wooden dog fence along the front of this area taller (by adding 3-foot pickets at 8 to 10-inch intervals) and installing a gate between the two sections of fence. That will make it possible to remove the goofy wire fence around the edge of the circular lawn. Aesthetics apart, that fence makes working in those beds way too hard.

Dog fences.

Dog fences.

The next step will be to identify the plants that do well here already, both “quality” and “weedy” types. Undesirables and struggling specimens will be removed and selected areas dug over and replanted. (Of course all these labours will be performed by me, but somehow I can’t quite bring myself to say “I will remove, dig, replant, etc.”)

I keep reminding myself I will have ten extra hours most days of the week in which to accomplish this stuff. One way or another, the place will look like this again. Or better.

The Back Garden, May 2010

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Tough Plants for Dry Shade, Part 2

This has been by far the most popular topic on this blog, especially now that people are getting back into their gardens and looking for suitable plants to add to them.

My first selections were really tough plants that are necessarily a little uncouth and seedy. Here are a few more, including more refined types.

Ceratostigma plumbaginoides, Plumbago, is a great plant for late summer and early fall, when it produces small, intensely blue flowers, sometimes with red-tinted foliage. It spreads, but not in a rampaging, ground-conquering way. Maintenance is simple — just cut the stems to the ground in winter or during spring clean-up. It works well paired with spring bulbs, since it sprouts out relatively late.

Ceratostigma plumbaginoides

Perennial Candytuft, Iberis sempervirens, is another reliable, moderately spreading, medium high groundcover.  The pure white flowers contrast nicely with the leathery, dark green foliage. It gets a bit lanky in shade, but can be cut back after flowering to keep it more  or less compact.

Iberis sempervirens

Several of the hardy geraniums do well in dry shade, but Geranium macrorrhizum is one of the best. There is a white form (although pink-tinted) that should please purists. Like the two plants described earlier, it spreads moderately but is not a pest. The foliage is rather strongly scented. Some find it objectionable, although one source describes it as similar to ripe plums or passion fruit. I can’t say I agree with that; it is an odd smell, hard to characterize, but not what I would call foul.

Geranium macrorrhizum

Sadly, my plants are not yet in bloom, but the picture also shows Euphorbia robbiae and a grey-green and white variegated ivy, both happy in dry shade.

The epimediums are wonderful in dry shade. For most of the year they are superior foliage plants. The foliage should be cut down in late winter or early spring, before the new growth starts. Flowers are produced soon after, in clusters on thin, wiry stems. Colours range from white through yellow to reddish. One of the best is Epimedium x perralchicum “Frohnleiten,” so reliable that it’s almost like furniture.  It does spread, slowly but relentlessly, so be prepared to take control measures around the edges of its territory.

Epimedium "Frohnleiten" with Iris and Tellima

Also in this photo is another good plant for dry shade — Tellima grandiflora, also known as Fringe Cups. The common name is more accurate than the Latin, in this case, since the flowers are quite small. They are fringed, however.  The leaves are somewhat rounded and lobed and are said to turn red in winter, although mine never do. This is a woodland plant native to the northwest coast of North America, that looks good with ferns and hostas.

Bergenias do well in both shade and sun. Naturally, they bloom better in sunny situations and some varieties have foliage that turns red in winter; this phenomenon also manifests better in sun than shade. However, they are patient plants that struggle along valiantly in pretty abysmal conditions such as are found under maples. There are several species; I confess I do not know to which mine belong.

Bergenia

Veronica peduncularis “Georgia Blue” is another low-growing plant (6 t0 10 inches high) with a slowly spreading habit, that does quite well in relatively dry, shady conditions. Dark blue flowers are produced in early spring. It’s good used as an edging for beds; can be clipped to shape after blooming.

Veronica "Georgia Blue"

The photo also shows foliage of Iris cristata (another good plant for somewhat challenging conditions) and an emerging variegated Hosta.

Another groundcover-type plant (do you detect a trend here?) for dry shade is Lamium maculatum “Pink Pewter.” There are many varieties of Lamium, but I have found this one to be reliable here. It dies out in spots, but resurges in other spots, so I always have it. Needless to say, if treated better (water and compost) it does better. The pink flowers in late spring look elegant with the silvery foliage.

Lamium "Pink Pewter"

Finally, a brief mention of Liriope (Lilyturf) and Ophiopogon (Mondo Grass). These related species form clumps of grassy leaves, ranging in height from a couple of inches to more than a foot. Blooms are white or purple, but it’s the whole plant that makes the visual statement. Ophiopogon japonicum “Gyokoryo” is a very dwarf form that spreads to form a grass-like mat. Near the Tommy Douglas Branch of the Burnaby Public Library I saw a fetching combination of what looked like Black Mondo Grass (Ophiopogon planiscapus “Nigrescens,” most likely) and some sort of ornamental variety of Horsetail — a very modernesque looking pairing.

A final word — this selection of plants is, as I have already said, less tough and hardy than those listed in my earlier tough plants posting. You can’t just plant them and forget them, especially in less than ideal spots such as under trees. Occasional watering, fertilizing and mulching helps, but even so, don’t expect these plants to perform to their maximum potential under challenging conditions. And yes, I have featured a lot of groundcovers. Visualize them forming a kind of tapestry, combined with hellebores, hostas, ferns and shrubs, with spring blooming bulbs for early colour.

Tough Plants for Dry Shade

I garden in a tough place.  OK, it is in Zone 8, so I can’t complain about cold winters or unfair frosts.  It’s a tough place because it’s dry.  Victoria B.C. has a Mediterranean climate, which means wet winters (but not as wet as some people think) and dry summers.  Not too hot, but dry.  Beth Chatto’s book The Dry Garden has a permanent spot on my bedside table.

In addition, on my 50′ x 120′ piece of paradise, there are four large maples (probably Norway), a big weeping birch and a tree of heaven (Ailanthus), which some may consider a tree from hell for its habit of sending up suckers and seeding profusely.  The soil is a sandy loam, emphasis on sandy.  Drainage is excellent, but much of the space available for growing plants is infested with tree roots, the fibrous feeding roots of maples, which suck up most of the available moisture and nutrients.

There are plants that will put up with these onerous conditions.  Some of them have weedy tendencies, but who’s perfect?  Gardeners with big, greedy trees to contend with can’t afford to be too fussy.

Lychnis coronaria (Rose campion). Grey-green foliage. Surprisingly shade tolerant. Magenta or white flowers in high summer. The white form is elegant. Seeds profusely.

Linaria purpurea (Toadflax). Tall skinny spikes with (mostly) dark purple flowers like tiny snapdragons, in summer. Also pink and even purple/white variegated types (rare). Another terrifically prolific seeder that does well in sun or shade.

Campanula persicifolia (Peach-leaved bellflower). Purple-blue or white cup-shaped flowers in summer — quite showy.  This one seeds vigorously and spreads by offshoots as well. Can be sneaky — once you have it, you have it everywhere.

Digitalis purpurea (Common foxglove). The white form is incredibly elegant, rising out of surrounding foliage in late spring/early summer. Even the ordinary magenta-pink kind looks better than nothing. It has “presence,” if nothing else. Another keen seeder. It’s a biennial, so the first year there is a rosette of leaves, the second year it blooms. With a certain amount of “management” you can have the white form only.

Stachys lanata (Lamb’s ears). A woolly grey plant with tiny pink flowers, usually recommended for sun, but does fairly well in shade. Looks elegant just as it is coming into bloom, especially against a background of darker foliage. Also seeds heartily. (Do you see a pattern here?  With all of these plants, you have to be vigilant about deadheading and pulling up unwanted seedlings, but you will always have some of them around).

Alchemilla mollis (Lady’s mantle). Interestingly shaped leaves that display water droplets beautifully. Clouds of tiny yellow-green flowers in late spring. Only moderately pushy.

Helleborus argutifolius (Corsican hellebore). In good conditions, this can be a big, fat shrub-like plant, 3 feet either way.  When competing with tree roots in shade, it’s sparser but still a presence. It blooms in winter — big clusters of icy green flowers which last well into spring, when they should be cut down to leave room for the new shoots.  This one seeds as well, but not as recklessly as the previously mentioned subjects.

Helleborus orientalis (Oriental hellebore). I have been really impressed by how well this one performs here.  It blooms prolifically, right under the maples (which have not leafed out yet, in March and April).  I cut the bloom stalks down in May, at the same time removing the rattiest leaf-stalks.  The dark green leathery five-lobed leaves maintain a solid presence in the beds throughout the summer.  Colours range from white (pure or spotted pink and purple) through a range of pinks to purples that can be almost black.

Anemone huphensis (Japanese anemone). The single white form is very reliable. It blooms late in the summer and into the fall, not as profusely as it would in better conditions, but…  The downside of this one is that it spreads by running roots, which can be a good thing, but usually isn’t.

Ferns, especially the genus Dryopteris (notice it has “dry” in its name), as well as the native species Polystichum munitum (Western sword fern) and Blechnum spicant (deer fern).  Ferns are solid, reliable and the opposite of weedy.

You can count on these plants to provide a solid foundation, even in dry shade. Then you introduce more refined subjects (lilies, hostas, daylilies, etc.) and try to keep them going.  Between the tree roots and the rowdy, self-seeding, colonizing tough guys, it can be a struggle!

More (relatively) tough plants in a future posting.