Kerria deserves a Second Look

Kerria japonica, The Japanese Yellow Rose, has been around for a long time. It has been sold for years, most commonly by low end mail order companies. For whatever reason, wholesale growers and garden centers rarely include this plant in their mix, and I wonder why? The more I see of this plant and what it can do in the landscape, the more I feel it deserves a second look. Please join me.

Kerria japonica is a hardy (Zone 5) deciduous shrub that matures at 3 to 5 feet in height. It's a dense mounded plant with numerous slender, zig-zagging branches that emerge at ground level. The beauty of Kerria is found in its flowers, stems and foliage. The bright yellow flowers are noticeable reminiscent of an old fashioned rose with its 5 petals. The flowers clearly make this plant a member of the Rosaceae family. In early spring, before the leaves emerge, the numerous yellow flowers create a colorful show. As an added benefit, Kerria will often rebloom off and on all summer long. The effect is beautiful and rewarding. Kerria is also blessed with attractive ornamental stems. From autumn to spring, its bright kelly green stems create a wonderful, fresh impression. Having visited the Cincinnati Zoo and Botanical Gardens in early spring a few years back, I distinctly remember big green drifts of Kerria. I was surprised and delighted to see it used throughout their beautifully landscaped grounds. Around every corner we were greeted by a mass of bright green. This unique combination of color and zigzagged lines creates a lasting impression.

You also have to appreciate the clean and simple foliage of Kerria. The leaves appear birch-like at first glance with its narrow triangular shape, but unlike birch, its leaves are brighter, doubly serrated, and display a pronounced puckering between the leaf veins. Always clean and green the foliage is a distinctive asset.

Culture

This is not a fussy plant that is difficult to grow or manage. Quite the contrary, Kerria is happy in most any reasonable well drained soil. It requires little fertility, and seems to flower best if neglected. Unlike other members of the rose family, Kerria has no serious insect of disease problems. The remarkable thing about this is that it thrives when grown in partially shaded to fully shaded locations. Few plants flower this well in shade! Full sun is also an option, but it does present a few problems. The flowers do not hold up as well and it can show some stem die-back if exposed to winter sun. Neither of these problems are severe, but both can distract from the beauty of the plant. It should be noted that this plant dislikes heavy, poorly drained soil. It will languish and grow smaller by the year. As far as ongoing maintenance, I personally feel this plant benefits from an occasional hard pruning. Cutting the plant to the ground produce a fuller plant, brighter stems and improved flowering.

The Cultivars

The most popular cultivar of Kerria is the old fashioned double flowered form, Kerria j. 'Pleniflora'. Its yellow button-like flowers resembles a chrysanthemum, and at peak bloom they polka dot the plant to create a distinct look. Kerria 'Pleniflora is not one of my favorite plants. To me it looks too contrived. I much prefer the simplicity of the single flowered forms. Two of the best single flowered cultivars are 'Honshu' and 'Golden Guinea'. I can detect only slight and inconsequential differences between these two plants. Both were selected for their large single flowers. If I had to choose only one of them I would pick ‘Honshu’ because its flowers are slightly larger and they have a soft and pleasing fragrance. The plant was introduced by Dr. Clifford Parks of Camellia Forest Nursery in Chapel Hill. Many people choose 'Golden Guinea' strictly because of its name. The name properly describes the size and color of the bloom. No the name Guinea does not refer to a bird or some exotic country, it refers to a large gold coin.

For those of you who need even more excitement in your life, several variegated selections are available. The best variegated type is called Kerria japonica 'Picta'. Not a great name, but a very good plant. Its leaves are graced with a creamy white margin that is not at all offensive like some variegated plants. The overall effect is very nice, and a decent specimen garners much attention. It does have its shortcomings. It can be slow growing when young making it difficult to produce especially when compared to the species. It also has a tendency to throw an occasional green shoot, which must be removed. This is a simple task and most gardeners would gladly pay this price to have such an interesting plant. I have seen another variegated clone under the name of 'Kinkan' or 'Auro-vittata'. This is worthless selection best left to the most ardent collector or relegated to the botanic garden. This "beauty" has green and yellow striped stems that tend to revert at the speed of sound and has small single yellow flowers.

While all Kerria selections have yellow flowers; the cultivar ‘Albaflora’ has blooms that are a near white, butter yellow. The color is more subtle, and I my opinion more pleasing to the eye than the typical bright yellow of the species.

Kerria is a beautiful plant with year long interest. Plant it in mass in a shady location and I think you'll be pleasantly surprised how nicely this plant performs. Very few flowering shrubs perform so well in the shade and you'll love the winter effect provided by its bright green stems.

Viburnum nudum: Close to perfection

Brandy Wine over three seasons

Possiumhaw or smooth witherod viburnum (Viburnum nudum) is a little known and underutilized shrub that is native from Maine and Florida and west into Texas. This is a remarkable shrub for several reasons; most notably for its attractive leaves that are so glossy you might think they’d been sprayed with leaf shine. As an added attraction the leaves turn to an eye-catching rich burgundy in autumn.


While attractive from a distance, the creamy-white, spring blooms are a bit uninteresting compared to other, more showy or more fragrant viburnums. To me its musky odor is neither pleasing or offensive - yet in late spring, the overall flower display is a welcome site in any garden. More importanly the flowers should be praised and respected for they give birth to an breathtaking fruit display that is unrivaled in the plant world.


In late summer the immature green, pea-sized berries (technically drupes) begin their metamorphosis - changing to shades of bright pink and then on to hues of bright blues and wild grape. The transformation is unsynchronized and yields large clusters of polychromic berries more showy than Donny Osmond’s dreamcoat.

Brandywine has colorful berries

While there is no such thing as a perfect plant, this one comes close. Still it is not suitable for all gardens. The species will not thrive on chalky or alkaline soils. In the North Eastern, U.S., Viburnum bark beetle can be a problem for this species, but fortunately these buggers can be controlled without chemicals. 


So how can such a beautiful plant escape full-blown stardom? As is the case with many Viburnum species, fruit set mandates that two distinct varieties (clones or ciltivars) are grown in close proximity to cross pollinate. And until the recent introduction of Brandywine™ (Viburnum nudum ‘Bulk’), most growers offered one cultivar called ‘Winterthur’ and it never set fruit. Brandywine was introduced by Proven Winners so that  there would be two selections available and thus allow for fruit set. It turns out, however, that Brandwine will set fruit without the need for another cultivar near by to cross pollinate. I have grown this plant for over four years and it has set fruit with a companion. 

Brandywine Fall color 

Brandywine Viburnum is hardy from zone 5(4) to 9. It prefers full sun to partial shade and moist, but well drained soil. It matures at a height and width of 5-7 feet. Once established it requires very little care yet offers so much more in return. 

The Gift: a passion for plants

While I spend most of my time looking for new plants, today I discovered some plants that were old but personally significant. My father sent me an email with a link to a website called Penny Postcards. On this site you can view old postcards arranged geographically by state and county. My father directed me to the cards for Linn County, Iowa. Here I discovered beautiful postcards of gardens designed by my late grandfather William Wood, the former manager of parks for Cedar Rapids, Iowa.

I’ve never met my grandfather. I am sad to say he died before I was born, but I do feel a closeness to William for like my father and me, he was a plantsman. He was trained in England as a true master gardener before he immigrated to the town made famous by Quaker Oats. I have visited the parks of Cedar Rapids many times and with each visit I was warmly greeted with the smell of cooked oats and the lasting remnants of William’s handy work; the Ellis Park golf course, the ruins of an old Shakespeare garden and trees planted by his caring hands. No, I have never met my grandfather, but still, I have come to know him. He loved plants and gardens, and he had a desire to share his passion with others, and that is the gift he gave to me.

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Addicted to Hydrangea

In the small coastal village of Varengeville-sur-Mer, in Normandy France, I had the pleasure of meeting the worlds foremost Hydrangea experts Robert and Corinne Mallet. Inside their small cottage, stacks of books, piles of herbarium specimens and a mass of photography towered about me and surrounded me. Everything within site, including the Mallets themselves, revolved around the genus Hydrangea. Call them advocates, fanatics or just plant crazy; they’ve devoted their lives to growing, studying and promoting Hydrangeas.

While I have other pursuits in my life, you might also call me a bit of a Hydrangea nut. After all - it was I who had traveled all the way to France to learn from the masters. Yes, Hydrangeas are a unique group of plants that can cast an inexplicable spell on those who grow them. To know the charm, beauty and usefulness of Hydrangeas is bound to create an enthusiast to some degree.

There are some 23 different species of Hydrangea. A few are evergreen, but most are deciduous forms of vines, shrubs or small trees. Where I live in Michigan, I can successfully cultivate about 10 different Hydrangea species. What is amazing is that only half of these species are readily available in the nursery trade and only five species of Hydrangea provide us with the hundreds of unique plants (cultivars) in which to beautify our gardens. While an unmentioned East Coast author (Martha Stewart) would espouse the beauty and bold brash colors of Hydrangea macrophylla (The Bigleaf Hydrangea), I would rather extol the virtues of some less glorious, but more reliable species. These Hydrangeas have proven themselves to be great garden plants for our harsh continental climate.

Climbing Hydrangea, Hydrangea anomala subsp. petiolaris (Eastern Asia, Zone 4 ) is a beautiful vine that climbs by aerial rootlets. It has glossy, heart heart-shaped leaves and white lacy blooms (corymbs) in early summer. It can be grown as a shrub, groundcover, or as a vine depending upon its culture. You have not lived until you have seen this plant in full bloom climbing up a tall oak tree. It is very happy on a north facing building or otherwise shady brick wall. I know of only a few cultivars, but most of them are hard to find in the market. 'Skylands Giant' is a selection with very large blooms. 'Tilifolia' is a selection with very small leaves, and ‘Fire Fly’ is good variegated selection with bold yellow and green leaves. All of these plants are worth hunting for and growing.

The Smooth Hydrangea, Hydrangea arborescens (Eastern U.S, Zone 3), is a wonderful, hardy plant that blooms in midsummer. It has the great advantage of blooming on the current seasons wood. This results in very reliable blooming regardless of frost or winter injury. The species is not a spectacular garden plant with its small mostly fertile flowers, but there are some noteworthy cultivars that are worth growing.

'Annabelle', introduce by Joe McDanials of Champaign, IL, is the most commonly grown cultivar. One is hard pressed to find any other cultivar of Hydrangea arborescens being sold today. There are some nurseries unknowingly selling the cultivars 'Grandiflora' as 'Annabelle'. True 'Annabelle' has very large, perfectly symmetrical blooms, while the blooms of 'Grandiflora' are often quartered and irregular. 'Annabelle' is very showy, but often collapses under the weight of its own blooms.

There is a need for more selections of H. arborescens. I would like to see an improved 'Annabelle' with sturdier stems. I also feel there is room for more lace-cap selections, especially selections made from plants like H. arborescens subsp. discolor which has light downy hair beneath the leaves and H. arborescens subsp. radiata which has snow white coloration on the underside of the leaves. I personally find these plants more graceful and delicate than 'Annabelle'.

There are three new introductions of H. arborescens on the market and both are very exciting. . Dutch horticulturist Wouter Kromhout brings us an exciting new lace-cap called White Dome This strong growing plant has extremely large dome-shaped blooms and large, attractive dark green leaves on a 5-6’ tall plant. This plant is exceptionally fine in the winter for its dried flowerheads look magical with a touch of frost or snow on them. (See image above). It can be mass planted to acheive the same winter interest you get with ornamental grasses like Miscantuhus.

Incrediball is a new and improved form of Annabelle with massive flowers and strong stems that hold up the blooms. This plant is larger in stature than Annabelle, reaching 4-4.5 feet tall.

Invincibelle 'Spirit' is the most exciting hydrangea introduction in years. It is the first pink flowerd form of 'Annabelle'. It was developed by Dr. Tom Ranney of NC State. Now we have the color of a Hydrangea macrophylla but with the dependability of H. arborescens. Very exciting!

Hydrangea arborescens is a very useful and adaptable plant. It grows in light shade or full sun, and once established it can be quite drought tolerant. Be careful not to over fertilize this plant or it will grow weak and leggy. I prefer to cut it back hard each spring to create a fuller bushier plant and to remove any winter damaged stems. In the landscape use it as a focal point for its white flowers can stand out from long distances. It also looks great in mass plantings.

The Panicle Hydrangea, Hydrangea paniculata (Asia, Zone 3) is a wonderful, hardy species that also blooms on new wood. It flowers in late summer to early fall. The cultivar Pee Gee or 'Grandiflora' is an old, commonly grown cultivar that deserves retirement. It has large floppy white panicles. Superior cultivars are now making their way to market. Most of these plants were developed by Robert and Jelena DeBelder of Belgium. 'Little lamb' is a DeBelder introduction with a dwarf compact habit. The flower heads are petit but full. They emerge a pure white and change to a rich pink in autumn. Pieter Zwijnenburg of Holland developed ‘Limelight’ a plant that is making quite the splash in the US. This incredible plant is noteworthy for several reasons. It sports attractive bright green flowers on strong upright stems. It blooms in early July, which is quite early for the species. ‘Limelight’ is at its best in autumn when the green flowers transform to breathtaking shades of green, pink and burgundy all on the same plant. I have seen numerous other selections of Hydrangea paniculata that are yet unnamed or introduced. We are currently evaluating a few selections but want to make certain that they are distinct and worthy before introduction. Also of note, the USDA has been attempting to cross H. paniculata and H. macrophylla in order to create a hardy, reliably blooming plant with interesting colors. Time will tell if this effort is successful.

Hydrangea paniculata is very easy to grow and adaptable to most garden soils so long as is it not planted in standing water. This plant makes a great blooming hedge if you don’t over prune it. Just let it grow and enjoy the color.

Hydrangea quercifolia (South Eastern U.S, Zone 5) know as the Oakleaf Hydrangea is a wonderful plant with distinct oak-like leaves. It has beautiful white panicles in midsummer that often fade to pink as they age. It is also noted for its blood red fall foliage color. The cultivar 'Snow Queen' is perhaps the standard by which all oakleaf cultivars are judged. It has large, upright panicles with large sepals and deep red fall color. 'Snowflake' is a beautiful, double flowered selection with large, pendulous panicles. The sepals age to purple even as new white sepals emerge to create a beautiful contrast. 'Harmony' has curious globular blooms. It is strictly a plant for collectors. Mike Dirr introduced a selection called 'Alice'. She has large panicles, good red fall color and extremely vigorous growth. Here too, we are evaluating other new selections that may warrant introduction.

Oakleaf Hydrangea is very reliable, easy to grow and thrives on neglect. It is extremely drought and heat tolerant. It will thrive in full sun or partial shade. It will flower in heavy shade but it will grow at a much slower rate. Use this plant in large mass plantings in commercial settings or as a specimen in a home landscape. Grow in contrast with plants with fine textures and narrow leaves. Please note that the wood on this plant is quite brittle, so it should not be planted where ice or snow could smash its structure.

As you can see, the genus Hydrangea is wonderfully diverse. But don't just take my word for it - the best way to know these plants is to grow them. But be careful, it’s fun and potentially addicting.

If you wish to learn more about Hydrangea I highly recommend the following books; Hydrangeas, Species & Cultivars a two volume set by Corinne Mallet, Hydrangeas, A Gardeners Guide, by Toni Lawson-Hall and Brian Rothera, and The Hydrangea by Michael Haworth-Booth. I also recommend joining the American Hydrangea Society, or if you're in Europe, the Shamrock Society.

Changing the Way We Garden

Changing the Way We Garden

Every once in a while, a new plant comes along and changes the way we garden. Case in point, Weigela florida (pronounced: Why-gel-ah). New introductions are forcing landscapers and gardeners to reassess its value and its how its used.

Long considered an overly large, old fashioned shrub of one dimension, newly introduced cultivars have extended its season of color and opened up new landscape applications.

The first major shift came about eight years ago when Herman Geers developed and introduced Wine & Roses Weigela, Weigela florida ‘Alexandra’ pp#10,772. Wine & Roses Weigela, with its dark burgundy foliage, proved that Weigela had ornamental value beyond its two to three week spring bloom time. While Geers developed the plant as an ornamental cut branch for the European cut flower market, it also made a big impact on the North American garden. It sparked a resurgence in the popularity or Weigela, as people began to use it in ways never considered before. Most radically, perennial gardeners began to realize that this plant was right at home in the perennial garden; a perfect complement to Rudbeckia, Perovskia, Echinops and a host of other pink, blue or silver herbaceous plants. Additionally, it found advocates that used the plant in mixed decorative containers and yes, of course, in the cut flower garden. No one ever dreamed of using Weigela ‘Red Prince’ or any of the older cultivars in such untraditional ways.

The next paradigm shift came about six years ago with the introduction of Midnight Wine Weigela, Weigela florida ‘Elvera’ pp#12,217, another Herman Geers development with dark burgundy leaves. At a mature size of 12 to 18 inches, as opposed to the typical 5 to 8' height of the species, this Weigela opened up even more garden applications. Before this plant, no one their right mind would have considered using Weigela as a bedding plant, edging plant or as a ground cover, but that is what’s happening today. In the spring of 2006, My Monet Weigela, Weigela florida ‘Verweig’ pp#16,824, joins Midnight Wine in this new class of miniature cultivars. This much anticipated gem sports brightly colored, tricolor leaves of cream, green and pink. Each of these minis can be used in place of such as coleus, silver mound Artemisia, creeping phlox, candy tuft and so on. You get the idea. A shrub that was recently seen only as a farmhouse relic is now perfectly at home in an annual display, perennial bed, a decorative patio container or for that matter a window box.

Plants like this change everything, and they keep gardening fun. As a plant hunter, I am always thinking about new directions in plant breeding and how they will change the way we garden. I am always on the hunt for plants that make gardening more rewarding or solve a problem. As residential lots get smaller and smaller, and as time becomes more precious, people will have less room in their garden for large, short season shrubs that require a lot of care.

New plants, particularly new flowering shrubs, are changing the way we garden.

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Food, Drink and Plant Hunting

For most Americans the thought of eating puffer fish or raw sea urchin is unthinkable, if not down right disgusting. I can honestly say from experience that dried cuttlefish is impossible to chew and that fried tripe is nearly impossible to keep down. But meals, especially meals in foreign lands and cultures are so much more than just a way to fill the tank. Meals are about people, cultures, friendships, relationships, communication and building trust. Food is one of the most enjoyable, and at times the most challenging, aspects of being a plant hunter. Food and drink is an intrinsic part of plant hunting.


It should come as no surprise that the ministry of Jesus was so closely associated with food and drink. He changed water into wine, fed thousands with a few fish and loaves, and dined with his closest friends in the upper room. But have your ever thought about what message it would have sent if Peter or one of the other disciples refused to eat the food Jesus offered? What if Andrew had complained about the wine at last supper? Refusing to share or even appreciate the gift of a meal is a slap in the face of your host, even if it’s barbequed sea eel and potato wine.


No matter where I’ve traveled, I have always eaten what my host has offered and I was always appreciative. In Mexico, I discovered that my host spent a week away from his family doing odd jobs just so he could buy the meat for our meal. While in Japan, a group of local nurserymen dug deep in their pockets to take us to one of the best and most expensive restaurants in Tokyo. In Korea, grower after grower bought the same expensive meal despite that fact that the price could have feed their families for a week. What message would I have sent to these people if I had refused their gift of a meal?


One of my most memorable meals was with a small grower along the Northern coast of France. I had often heard that the French people are rude, but I have found the complete opposite to be true. This particular nurseryman was so thrilled that we had travel so far and had taken time to visit his humble nursery. He insisted on popping open a bottle of Champagne. We had not known each other 30 minutes earlier, but there we sat, is his home talking about plants, the nursery business and life as we shared the bottle and food. I do not normally drink so early in the day but who am I to refuse this mans gift?


Over the course of that meal we learned that his home had been occupied by Germans for four years during WWII. He parents had been taken off to concentration camps, while he and his brother were forced to run the farm and feed the German soldiers.


But on this day he was feeding Americans, and for him that was reason to celebrate. Soon after D-day this man’s home was liberated by American troops. In the the four months that followed, he and his brother joyfully shared their home and meals with these young American boys. And now, nearly 60 year later we sat in the same home and shared food and drink. Together we ate, drank and laughed and yes even cried as he told us that his father and Mother never returned from the camps. All of this - over a few hours and a meal.


Perhaps now you can see why I never complain about the food when I travel. Meals are not so much about the food, but rather about the people whom you share them with. Food is about friendships, relationships and sharing. It is also one of the most joyous aspects of being human.


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