I’m honored and delighted to be taking part in April’s Garden Designers Roundtable as a guest blogger. I’d feel out of place contributing on a design-specific subject in the company of all these professional designers, but I never run out of things to say about my favorite plants, so I jumped at the chance to join in on this topic. The hard part was deciding which plants would make the cut. Going with the “landscape” aspect, and attempting to keep this post a semi-reasonable length, I settled on three of my favorite woody plants.
Southern Bush Honeysuckle (Diervilla sessilifolia)
First up is southern bush honeysuckle (Diervilla sessilifolia). I’m not sure why I originally bought this shrub, because honestly, it’s not a dramatically interesting plant, either in foliage or in flower. But it does have a number of good qualities that, taken together, make for a dependable and pleasing garden and landscape shrub.
For me, southern bush honeysuckle has a low, neatly mounded form, likely because I cut the entire plant back to about 2 inches each spring. I understand that when it’s left unpruned, it can reach 4 to 6 feet tall and wide; mine are usually just 2 to 3 feet tall and wide.
The soft yellow flowers aren’t very large, but they’re quietly pretty, and they show off well against the rich green leaves. (Bees love them, too.)
They appear over a long season, starting in June here in southeastern Pennsylvania. Below is southern bush honeysuckle with golden elderberry (Sambucus nigra ‘Aurea’) in late June.
Flowering continues through the summer. Below is a mid-July shot of southern bush honeysuckle with golden oregano (Origanum vulgare ‘Aureum’) and golden locust (Robinia pseudoacacia ‘Frisia’).
The flowers keep coming through August, at least, and often well into September. Below is a late August shot of southern bush honeysuckle with frost grass (Spodiopogon sibiricus) and ‘Karley Rose’ Oriental fountain grass (Pennisetum orientale).
In fall, the green seed capsules darken to a rusty red-brown, which shows up well against the still-green leaves. Below, they’re set against fall-browned frost grass in mid-October.
And here’s a seedhead against Tatarian aster (Aster tataricus) and Japanese maple (Acer palmatum), also in mid-October.
In mid- to late fall, the foliage finally starts to color up. Depending on the weather, it can be anything from bright red to russet to orange with touches of yellow. Below it’s in mid-October…
And here it is in the foreground of a mixed planting in mid-November:
Even the winter form is attractive (below in early February).
Southern bush honeysuckle spreads by rhizomes, which can make it a little challenging to manage in mixed plantings. I don’t find it to be an aggressive spreader, but I wouldn’t recommend planting it with delicate companions. It’s fine with sturdy partners such as warm-season ornamental grasses. I’ve also had luck keeping it in place by snipping off and pulling out the surface runners when I do the spring cut-back. I’ve used those rooted pieces to make many new clumps for mass plantings, or for wherever I need a free filler. I’ve read that the plants can work well as a ground cover for slopes, and I’m tempted to try that out.
Southern bush honeysuckle is native to the southeastern U.S. but is hardy as far north as Zone 4. It thrives in full sun to light shade and reportedly prefers well-drained soil, though it does fine here in rather moist soil. One other good thing: deer don’t seem to care for it.
For a zippier foliage effect, look for the brightly variegated selection Cool Splash (‘LPDC Podaras’). (I’ve written about this one before, in Making a Splash.)
Silver Willow (Salix alba var. sericea)
When I was a new gardener and busy absorbing British gardening books, I fell in love with silver willow-leaved pear (Pyrus salicifolia ‘Pendula’). Knowing how common the bacterial disease fireblight is on pears where I live, though, I figured I’d never be able to grow it successfully. I finally found a reasonable substitute in silver willow (Salix alba var. sericea).
Like the silver pear, silver willow has slender leaves that are bright silver to silvery gray through the growing season. Silver willow, however, will likely get much larger than silver pear. I’ve read that silver willow can eventually reach 30 to 50 feet tall, but I’m hoping that the descriptions that claim about 20 feet are more accurate.
Below is silver willow with ‘Silver and Gold’ yellow-twig dogwood (Cornus sericea) and ‘Screamin’ Yellow’ baptisia (Baptisia sphaerocarpa), showing the pyramidal habit the plant had when it was young (about 4 years after setting out a 30-inch mail-order plant).
Over the last few years, it has gradually become more rounded. Below, it’s with ‘Karl Foerster’ feather reed grass (Calamagrostis x acutiflora), Joe-Pye weed (Eupatoriadelphus maculatus), and white snakeroot (Ageratina altissima).
I prefer not to limb up my trees, but I didn’t have much choice with this one, so I cleared the bottom 5 feet of the trunks to give the perennials and nursery bed under it more room and light. (So far – after about 8 years – I haven’t had any major problems with planting among the surface roots.)
Silver willow can also tolerate heavy pruning, so I still have the option of cutting it back hard and letting it resprout, though I’m hesitant to interfere with the graceful look it has now.
With its dense, bright foliage, silver willow has turned out to be a great background for a wide variety of colors and combinations.
Above is silver willow behind giant fleeceflower (Persicaria polymorpha) and Mexican feather grass (Stipa tenuissima) in mid-June. Below is the same setting from a slightly different view one year later, with flowering silver sage (Salvia argentea), ‘Caradonna’ salvia, and ‘Brookside’ geranium in front of the fleeceflower and willow.
Above is the willow in mid-September a few years earlier, behind Leucanthemella serotina, blue mist shrub (Caryopteris x clandonensis), and silver sage. Below, it’s a backdrop for ‘Cassian’ fountain grass (Pennisetum alopecuroides), ‘Fireworks’ goldenrod (Solidago rugosa), golden lace (Patrinia scabiosifolia), orange coneflower (Rudbeckia fulgida var. fulgida), and ‘Silver and Gold’ yellow-twig dogwood in late August.
Above is silver willow with ‘Old Spice Mix’ sweet peas (Lathyrus odoratus) in early July. And below, it’s with ‘Crimson Beauty’ fleeceflower (Persicaria cuspidata) and ‘Jocius’ Variegate’ white snakeroot (Ageratina aromatica) in mid-October.
Above is a long view with silver willow behind a border that includes ‘Cassian’ fountain grass; seedheads of purple coneflower (Echinacea purpurea), spike gayfeather (Liatris spicata), and orange coneflower; ‘Fireworks’ goldenrod; a pink New England aster (Symphyotrichum novae-angliae); ‘Dallas Blues’ switch grass (Panicum virgatum); Tatarian aster (Aster tataricus); little bluestem (Schizachyrium scoparium); and ‘Dewey Blue’ bitter switch grass (Panicum amarum).
Below is the same border one year later but six weeks earlier in the season, with Carolina lupine (Thermopsis caroliniana), purple coneflower, golden lace, ‘Dewey Blue’ bitter panic grass, orange coneflower, ‘Karl Foerster’ feather reed grass, and Joe-Pye weed.
Silver willow needs full sun and thrives in moist soil, but apparently it can also adapt to average or even dry conditions. I’ve found a wide range of hardiness ratings for it, most often Zones 3 or 4 to 8 but sometimes even to Zone 2.
Daimyo Oak (Quercus dentata)
Here’s another plant that I can’t remember buying intentionally. That happened a lot around the time Hayefield House was being built, because a fantastic local nursery was closing that year. I made several trips there to buy as much as I could, and though oaks don’t usually grab my attention, this one – known as Daimyo oak, Daimio oak, or Japanese emperor oak (Quercus dentata) – somehow ended up in my cart.
Like most of the woodies I planted at Hayefield in 2002, this oak was just about 1 foot tall, with a single stem. Over the years, it has outgrown every other tree here (except for the silver willow), putting on at least a foot of new growth every year. So much for oaks always being slow-growing.
I have it planted out front, at the intersection of three large borders, where it makes a gorgeous deep green backdrop for much of the growing season. Below is a view of it behind giant fleeceflower and purple coneflower in mid-June.
Above is the oak in a second flush of growth in late July, with the same giant fleeceflower and purple coneflowers, and little bluestem too.
By late August, below, the oak is back to deep green.
Daimyo oak really comes into its own in fall (mid-November, below), with spectacular autumn foliage colors: usually shades of orange with touches of gold.
Above, in detail: the seedheads of purple coneflower and Culver’s root (Veronicastrum virginicum) with prairie dropseed (Sporobolus heterolepis), ‘The Blues’ little bluestem, pink muhly grass (Muhlenbergia capillaris), ‘Sioux Blue’ Indian grass (Sorghastrum nutans), aromatic aster (Symphyotrichum oblongifolium), more purple coneflower seedheads, and species little bluestem. And Daimyo oak, at the far end.
Below is a late October shot with the oak behind ‘Dallas Blues’ switch grass, ‘Cassian’ fountain grass, and a seedling Japanese maple (Acer palmatum).
Above is view from a slightly different angle, with the oak and ‘Dallas Blues’ switch grass as a backdrop for Tatarian aster and the seedheads of Carolina lupine.
And below, one more different view from the same day, with more fall color: red Bowman’s root (Gillenia stipulata), light yellow ‘Dallas Blues’ switch grass, and bright yellow Arkansas bluestar (Amsonia hubrichtii), plus the dark seedheads of orange coneflower and purple flowers of aromatic aster.
The color is splendid even in November (above and below)…
…finally turning brown in December (above). The foliage is marcescent, which means that it hangs on through the winter (below, in early February).
The leaves of Daimyo oak are huge (to about 1 foot long and 6 to 8 inches across), so they really catch the snow and ice. They also make quite a bit of noise when they rattle in winter winds. On the plus side, they provide excellent screening in winter as well as summer and fall.
Finally, after a few warm days around late March, the old leaves loosen and drop, making room for the new growth a week or two later.
Daimyo oak flowers in May and produces showy acorns later in the summer. Mine flowered and fruited for its first time last year, but I missed getting a photo of its frilly-topped acorn.
This oak isn’t for a small landscape: I’ve found reports of anything from 50 to 75 feet as its ultimate height. I probably should have given it even more room at planting time. Even if it keeps growing 1 foot a year, though, I doubt I’ll have to worry about it getting too big for its spot in my lifetime.
Daimyo oak thrives in full sun and average, well-drained soil in Zones 5 to 8. Forestfarm sells plants of the species; Gossler Farms Nursery offers the cultivar ‘C.F. Miller’ and cut-leaved ‘Pinnatifida’.
Ready to find out about the favorite landscape plants of official Garden Designers Roundtable members? Check out these links: