Purple alliums, columbines and camassias fill a display border at Longwood Gardens in Pennsylvania.
Parts of Canada are still snow-covered (at least where I garden), but thankfully it’s March and milder spring weather can’t be far behind. Here are two of my favourite spring plant combinations that would be easy to recreate in most Canadian gardens. The first was inspired by a visit to Longwood Gardens in Pennsylvania last year; the second is a coincidental pairing from my own garden that I hope to expand upon this year.
Combo One: The spheres of tall alliums (possibly ‘Purple Sensation’) punctuated a planting of frilly mixed columbines (Aquilegia hybrids) in a perennial border at Longwood. Adding sparkle and more soft blue were camassias, a late-blooming spring bulb.
Longwood dismantles its main display borders each season, impractical for home gardeners. If I were recreating this border in my own garden, I would want to extend the colour into summer. By weaving in daylilies, tall veronicas and Verbena bonariensis — all plants with fairly narrow profiles — I would accomplish this, and extend the pink, purple and white colours of this border. Admittedly, the verbena isn’t hardy, but it often self-seeds as long as you’re careful not to weed out the seedlings in early spring.
The rich colours of snake’s head fritillary and brunnera offer a spring surprise.
Combo Two: This was pure serendipity. One fall, I transplanted a clump of unvariegated Siberian bugloss (Brunnera macrophylla) to fill a bare spot, not realizing dormant snake’s head fritillaries (Fritillaria meleagris) were resting there. The following spring, the checkered blooms of the fritillary poked up through the dense bugloss foliage and the blue bugloss and maroon fritillary flowers made a pretty tapestry of rich, saturated colours.
The hardy bulbs mentioned in these two combinations need to be planted in the fall. The perennials (with the exception of the verbena) are hardy to at least Zone 4, and are easy to find in most garden centres.
I like columbines of all kinds, especially the long-spurred beauties that remind me of swallowtail butterflies. I’ve had many in the garden, but some years they make an inviting treat for the infamous leaf miners that plague these plants. They can almost be heard galloping in for a good meal. Sometimes, my columbines were ravished before they could bloom, and the only thing to do was remove the plants.
Japanese fan-leaved columbine and poppies. (Photo by Brendan Zwelling)
That sorry state of affairs resulted in a few years without columbines until I came across two that seem resistant to the miners. First to bloom is the lovely Japanese fan-leaved columbine (Aquilegia flabellata, Zone 4), a dwarf plant growing about eight inches (20 cm) tall and wide, with milky white or pale blue nodding flowers. The attractive blue-green foliage is extra thick, and the plant blooms early in May for about six weeks. It makes only one or two seedlings each year, and the colours are true to the parent. I appreciate having some to move around, but always wish for more.
Then, I read Patrick Lima’s recommendation (in his classic book, The Harrowsmith Perennial Garden: Flowers for Three Seasons) for Biedermeier Group hydrids (A. Biedermeier Group, Zone 4), another compact columbine resistant to leaf miners, growing to 12 inches (30 cm) and blooming in late spring. (The many flower stalks extend the height to 18 inches / 45 cm.) This plant starts blooming as the Japanese fan-leaved columbine is finishing, and makes bright pastel clumps loaded with flowers through the middle of summer. The flowers face up and have been called nosegay columbines, because they’re suitable for small vases and little bouquets. Sometimes my clump of Biedermeier makes a seedling or two, and their colour is a bit muddy. I’d really like more of these, too. They seem to be erratically available, probably because of the popularity of the taller and larger hybrids in the Music and Barlow Series.
Columbines are short-lived perennials, and it’s always good to have a few younger plants around for insurance. Both the fan-leaved and Biedermeier types can be grown from seed, and after several years they’re still resistant to columbine leaf miners.
Now, about those leaf miners. There is more than one kind, and at least three species in the genus Phytomyza are associated with columbines. I’m outnumbered! What’s more, they can all be feeding on the same foliage together, and each species has two or three generations in a growing season. They overwinter as pupa in the soil and then morph into flies that lay eggs on the underside of leaves. The eggs hatch into maggots and once inside the leaf tissue, there’s no way of getting at them. Some make blotch-like mines in the foliage, others make serpentine paths. This is very bad news. These columbine miners are another devilish insect (along with the horrid red lily beetle) added to the list of “plagues I have endured.” However, I’ve got the jump on them now with Japanese fan-leaved and Biedermeier columbines. You’ve got to stay one step ahead of the pestilence.
White spruce cones, near Lacombe, Alberta (Photo by cj berry on Flickr via Wikimedia Commons)
Cool days are here, and it’s time to address the more arduous tasks that we avoided in warmer months: soil renovation. Now that we know full-scale tilling and turning over of soil disturbs the delicate microbial systems at work beneath our feet (no more double digging!), we can be more selective about where to make improvements. My strategy is to improve the drainage and oxygen content in the soil surrounding perennial plants, and anywhere I’m counting on plants to produce sustained bursts of bloom through the season.
Perennials starved for oxygen can’t make lots of flowers. Plants take up oxygen (and nitrogen in gaseous form) through their roots, and a healthy supply is essential for flower production. Dense or compacted soil has few pores, or air spaces, for water to drain away and to allow oxygen to penetrate the root zone.
How to do your own soil renovation
I dig in generous amounts of leaves around perennials when I divide or move them, and also the cones from a white spruce tree (Picea glauca, Zone 3) brought down from a neighbour’s cottage and planted in my garden six decades before I lived here—so it’s not a baby! The small cones that fall on the lawn are simply trodden in, and I collect a basket from under the tree to use as a soil amendment. Their bulky form holds oxygen in the soil, and they’re just the right size for roots to grow around in planting holes. Yes, a gardener’s eccentricity, but I wouldn’t be without them. You might find a white cedar in a city park, on a university campus or at your cottage, and now is a good time to look for cones under it. I also have a large Norway spruce (Picea abies, Zone 4), which produces bushels of wonderful needles I also use in planting holes.
Another soil amendment I rely on is rock in various sizes and forms. Using rock materials as amendments improves the porosity of clay-based soil. Of course, rocks come in many mineral compositions and sizes. The one rock material absolutely not to use in soil is limestone screenings, which are used as foundation for stone or brick walkways and patios. Limestone screenings are chalky-white crushed pieces of almost pure lime, and highly calciferous (alkaline)—plant roots shrivel up in contact with them. Fortunately, they are manufactured and not something you’d find lying about the garden, so you’ll easily avoid them.
I always have a bag or bucket of simple crushed stone grit, or quarter-inch gravel, or half-inch pea gravel that I mix into planting holes to improve the movement of water and oxygen around plant roots. If a perennial is doing poorly, but shows no signs of disease, I’ll lift it and renovate the hole with whatever rock material is on hand, then settle the plant back in. It’s often difficult to identify the mixed mineral components of these materials, but my general rule is never use rock that appears too white (that lime issue again). Dark or dull grey (sometimes splashed through with semi-translucent quartz, or sparkly with mica) is always a good sign as it indicates the presence of granite, an acidic igneous rock that helps balance the pH of our alkaline soils in southern Ontario.
Finding these materials isn’t always easy, and construction-supply yards and stone quarries often require a minimum purchase of several cubic yards. Sometimes they will admire your interest and allow you to fill your bucket for a small cost (or no cost at all). The easiest rock material to acquire is coarse builders’ sand, sold at home improvement stores. The particles in play sand or horticultural sand are too fine and small, and will make soil dense, quite the opposite of creating pore spaces. Roll sand between your hands to test the particle size—play or horticultural sand will be soft and smooth, and you won’t feel individual grains. But coarse builders’ sand has larger particles, and it will be sharp, with individual grains you can feel. No, I don’t have rocks in my head—they’re in my garden soil!
Biedermeier columbines (Photo by Brendan Zwelling)
Defeating the columbine leaf miner
Cleaning up the garden gives me a chance to remember how much pleasure has come from individual plants—in this case, dwarf Biedermeier columbines (Aquilegia Biedermeier Group, Zone 4), sometimes known as the nosegay columbine because of its flower-packed stems, just ready to be cut for a small bouquet. Let me say they aren’t really so dwarf—described as 12 inches (30 cm) tall, but more like 18 inches (45 cm) in flower. Columbines are usually short-lived perennials, disappearing after a few seasons. But my Biedermeiers have hung on for five years, and produced a few seedlings with clear and attractive colours. I think it was Patrick Lima who wrote about their resistance to columbine leaf miner, a pest I have herds of here on the ranch! You’re probably familiar with the circuitous white tracks they weave through leaf tissues, eventually sapping the plant of energy and causing wilt. But the Biedermeiers are not to their taste and the miners leave them untouched. The strain has benefited from a bit of the hybridist’s art, and their flowers are outward facing and fully visible.
Still blooming: yellow fumitory
Corydalis lutea (Photo by Brendan Zwelling)
What would I do without yellow fumitory (Corydalis lutea, Zone 4)? It seems to have the genius of finding a perfect place for itself, filling vacant dusty corners and draping sprays of bright yellow flowers over rocks and between the bare ankles of shrubs—but never anyplace where I would want it removed. Does this plant read my mind? In mid-October yellow fumitory is as bright and full as it was in July. It spreads by seed, and acquiring just a few pots will insure you have it for all time. If it should pop up inappropriately, a gentle sigh of dissatisfaction will easily remove it.
Thanks for stopping by at Garden Making—hope to see you next week.