Scanning the trusty Plant Spotlight archive on this site, I realize I haven't done a very good job of nailing down what I consider to be the fifteen or so essential perennials for northern gardens. Correcting this oversight is my plan for this new season, so naturally I'm starting with Coral Bells.
Sometimes I forget how many gardeners aren't familiar with the plant. Interestingly, I was speaking on the topic of perennial plant combinations in Florida this winter, and I kept mentioning Huechera/Coral Bells to the audience, in a matter of fact, you-all-know-about-it way, and it turns out they can't grow it that far south. They can't grow Siberian Iris, or peonies, either. So chalk one up for us frigid fools from the tundra.
It's all about foliage, and in this regard, Heuchera is hard to beat. Leaves appear in great abundance, are heavily lobed, and, depending on the variety, may be roughly maple-leaf shaped or even more esoteric. Topside of leaf is a different color/hue than the bottom. It's a low (usually 6"-12"), mounding plant, which sends up slender, leafless scapes of tiny flowers mid-season. Colors range from white to a variety of pinks. In bloom they look like tiny fireworks.
Interest has grown immensely in the past few years, and valuable new introductions have been a part of that. Most common include 'Amethyst Mist' (amethyst w/ silver foliage), 'Chocolate Ruffles' (chocolate foliage, burgundy underside), 'Jade Gloss' (silver-red foliage), 'Palace Purple' (greenish purple foliage, light purple underside), 'Pewter Veil' (purple w/ silver foliage), 'Plum Pudding' (plum-purple w/ silver veining) 'Regina' (burgundy w/ silver veining).
There are literally dozens more; full botanical genera and species range through Heuchera americana, H. x brizoides, H. micrantha and H. sanguinea.
Care and Use
Coral Bells develop woody crowns that tend to grow up out of the ground after just one season. Push it back down, or add soil to raise the level of soil up around the crown. Divide the plant in spring every two to three years, discarding woody portions of crown.
Be sure to provide winter protection to plants the first winter after planting. But you need to remove the winter mulch early in the spring, as the plant is prone to suffocating if left covered too long.
Very hardy in Zone 4, hardy in Zone 3 with good seasonal care and winter protection.
I don't think you can create a truly great garden without growing Bearded Iris. Superb hardiness, essential foliage, and, in my mind, one of the prettiest bloom forms of any perennial make Bearded Iris a must for the northern garden.
What's that you say? You've heard that Bearded Irises are hard to grow? Nonsense. Bearded Irises love growing in northern climates; all it takes to grow most cultivars successfully is a smidgen of what's known as gardening.
Speaking of cultivars, there are far too many to mention here. There are more than twenty thousand named varieties. That's right. A two followed by four zeroes. And you thought some nursery geeks go a little overboard when it comes to daylilies.
What other plant gives you this great, broad, slash of leaf? Start planting Bearded Irises for the form of their foliage. It contrasts with nearly everything in the garden.
Your nearest nursery will stock at least ten varieties, perhaps thirty, and Bearded Iris are very popular in the mail order nursery business. Some nurseries specialize in the plant, and sell nothing else. You should be able to purchase any size and color Iris you have your heart set on. Bearded Irises bloom in just about every color (and color combination) on earth.
Care and Use
Some years ago, Bearded Irises were divided into seven classifications during the several all-night meetings of the American Iris Society. They based these classifications on height of scape (the stem, measured from base to bloom), flower size, and bloom time, sort of. They are:
There. Now you know what happens when the bar stays open late for members of the American Iris Society. Still, the classifications serve to steer you toward the height of Bearded Iris, and time of bloom in the season, that will best serve your garden.
TB are the largest, most common, and popular; SDB is a popular class with good disease resistance; IB is an important group as they are the only offering mid season bloom; MDB is fun for rock gardens, and expand quickly; AB is the most obscure and the only group that are somewhat difficult to grow.
Bearded Iris like sandy soil that drains well. This is the only reason I can think of that has led some to say that they are difficult to grow. Planting Bearded Iris? Dig up the soil in the area to a depth of twelve inches, shovel it into the wheelbarrow. Add some coarse sand to comprise 10-20% of the soil mix. Toss in a little organic material if the soil hasn't had any in a while. Dump it back in, tamp it slightly, plant.
Bearded Irises love full sun, and need at least five hours of direct sunlight to stay healthy and bloom at their fullest. I do have a few that receive just under four hours of direct, midday sun, and they bloom OK, and grow larger each year, but that's the minimum.
Bearded Irises grow from rhizomes, thick, fleshy stems from which the roots protrude. The only trick to growing Bearded Irises (after you've amended the soil as above) is that you not plant them too deeply. The top third of the rhizome should be visible after planting.
Bearded Irises like average moisture (1" per week) until bloom. After bloom, reduce amount of watering. They go into a semi-dormancy, and you don't want to water them much more than a little every two weeks or so. Later in the season you'll note they have returned to vigor and begun producing new rhizomes. Resume normal watering. Best bloom is produced by fertilizing with 5-10-10 fertilizer early in the season, next few weeks would be fine, then again as you notice the flower buds emerging from the leaves.
If you've inherited some Bearded Irises but they don't bloom, there are three reasons:
I do so love it when the Muscari blooms in my garden. A couple hundred started two, three weeks ago, and are in full force right now, on May 12.
It's important to break the tulip-and-daffodil, tulip-and-daffodil mantra that impacts so many newer gardeners. Daffodils have their moments, but tulips can be a pain in the ass. Meanwhile, there are numerous other spring blooming bulbs to incorporate into the garden; Muscari is one of my favorites.
There are around 30 different species, but only four or five commonly available in the trade. The nice thing about them is, like most bulbs, you get good results ordering from mail-order catalogs. Regardless of how or where you buy them, they are truly a "plant and forget" flowering bulb, laughing off the coldest winters, then coming back stronger year after year.
M. armeniacum is the most common, the blue variety that most know, but pictured in my garden (mixed in with a Sedum) is the one I prefer, M. botryoides 'album'. It's nearly pure white, and at the front of the border (or sweeping away from view in swaths) it's arresting. An added benefit is the sweet fragrance found with most (not all) species.
And in the north they are virtually impossible to kill. I think I planted these bulbs about ten years ago. I often forget exactly where they are, since they are everywhere. Later in the season, when their leaves have all but disappeared, I don't worry when I dig, or move stuff, or plant something in or on them. No matter how much abuse, they are always cheerfully in bloom, right on time, next spring.
Care and Use
All species hardy to Zone 3, M. latifolium reliably hardy to Zone 2.
Astilbes are an essential perennial, one of the real stars of the light shade garden. What gives them their power is the one-two punch of terrific bloom habit combined with great foliage.
Blooms are plume-like, in a wide range of colors, mainly the white-to-pink-to red range, though I grow a peach-colored knockout the exact name of which I do not know. That's what you get for dealing with an unlicensed vendor at a roadside stand outside of Madison, Wisconsin. Earnest socialist, one can only imagine. He did sell me three very healthy plants, to his credit. Foliage varies from long and oval to broad and lace-like. Most sport foliage that is a very attractive deep green, often serrated.
Plants vary in size from twelve inches to a few reaching three feet. Bloom time is typically early summer. Deadheadng does not induce more bloom; in fact, the plants look best if flowers are allowed to develop into seedpods for fall interest.
Care and Use
Astilbes like their soil on the humusy rich side, so work in extra organic matter. They are heavy feeders, so fertilize with a granular all-purpose (10-10-10) if your soil is neglected, I don't have time right now to find out exactly why it is that your soil is neglected, you're off the hook until a later date. One mistake some make is planting Astilbes in full sun, where they tend to curl up into crispy brown origami. There are a few varieties that do better in full sun than others, but in general, full sun for this plant is not a good idea.
Nor is any semi-shady situation in which the soil is allowed to dry out. You grow Astilbe, you water them twice a week in periods of no rain, that's just the way it is. They are greatly helped by summer mulch placed around their base, to keep soil moist and roots cool. They will bloom respectably in some pretty shady spots, but do not bloom well in full shade. Find a spot where they get an hour or three of direct sun, or dappled shade throughout the day, you're laughing.
Among my favorites: A. japonica 'Rheinland' (rose-pink); A. chinensis 'Visions' (raspberry-pink, cute and little); A. arednsii 'Granat' (deep red, wonderful purplish foliage in early season). Astilbe combines well with most other part-shade plants, working particular magic when combined with hosta, pulmonaria, lamium, and asarum. Division is a good idea every three to four years, as you see the center area of the plant clearly die out.
You see Astilbe listed as Zone 4 some places, Zone 3 others, consider all varieties worthwhile.
Here's a big, beautiful, easy-to-grow perennial, offering a commanding, shrub-like presence from June through September. In late August, 'Desdemona' erupts with beefy, daisies-on-a-bender blooms that last a solid three weeks. Bloom time depends on exposure; plants grown in mostly shade bloom later, and one of mine is just hitting peak bloom now, as we enter the second week of September.
Leaves are leathery, huge, rounded, and deep green, with purple undersides and petioles (leaf stalks). Topsides of newer leaves contain purple veining; leaves are born in great abundance throughout the plant's mounding form, and look great all season. 'Desdemona' will grow from three to four feet tall, with an equal spread.
Care and Use
It was after gardening for some years that I finally realized that perennials that prefer only a half-day of sun are often the best looking, most long-lived and disease-free. An ideal planting spot for 'Desdemona' is where it receives morning sun and afternoon shade. This plant (like all Ligularias) will wilt in the afternoon when planted in full sun. The plant will do very well in locations where it receives all-day, light to dappled shade
If you have a spot that is shaded in the morning but receives from one to three hours of afternoon sun, or three or four hours of sun at the very end of the day, that'll work too. All you have to supply is ample water. Ligularias love moisture, similar to Astilbes. This is a great plant for a bog or moist, low-lying area. They also look great alongside ponds and streams. I grow three, scattered around my informal beds, and remember to water them deeply twice a week. A two-inch layer of mulch around the plant, applied on or after June 15, helps keep the soil moist and cool.
Bloom color is distressingly close to orange, but it's best described as a yellow-orange. The plant is not terribly particular about soil type, but like most perennials prefers soil that has been amended with organic matter, as this helps the soil retain moisture, among other benefits.
The plant rarely requires division. I divide every five to six years, just to make more plants. Deadheading does not encourage rebloom, but will keep plants looking good after flowers have faded. You may want to prune off the larger leaves later in the season, if they become tatty.
Combine 'Dentata' with other shade and part-sun plants with spiked, long, or serrated foliage. The plant combines quite nicely with the popular Ligularia stenocephala 'The Rocket' and L. przewalskii in addition to hostas, ferns, Pulmonaria, Thalictrum and Heuchera. Hardy to Zone 4, worth a try in Zone 3 with good fall care and winter protection.
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