Disease-resistant and beyond pretty, the newest introductions promise to restore the popularity of this favorite flowering tree
by PAUL CAPPIELLO
GARDENWORTHY DOGWOODS can be found all around the globe, occurring in most corners of the Northern Hemisphere and in a smattering of places south of the equator. They include woodland-dwelling groundcovers of the north country, 70-foot trees of the Himalayas, the indestructible shrubby species of Europe, and that king of the garden clan, our native flowering dogwood (Cornusflorida).
The 1950s and ’60s were the glory days of dogwood improvement, especially among C.florida. Scores of selections were introduced for heavier flowering, larger bracts, deep pink bracts, and red-tinged spring leaves. But in areas where the dreaded dogwood anthracnose (Discula destructiva) has taken hold over the last three decades, straight flowering dogwood has become less than a hot commodity. Indeed, for years now, we’ve been hearing that dogwood andiracnose has rendered useless one of our most beloved and celebrated groups of trees. However, recent introductions are making it obvious that there is plenty of life still left in the Cornus clan.
The birth of the modern improved garden dogwood came in the early 1980s, with Dr. Elwin Orton’s introduction of the first C.florida C. kousa hybrids. Originally introduced under the umbrella of the Stellar hybrids, several of the original six have become mainstays in garden centers. While young plants take a few extra years before flowering, and then flower a tad later in spring than our native flowering dogwood, they combine outstanding vigor with excellent resistance to both dogwood anthracnose and the increasingly problematic powdery mildew. True, most of them don’t have the same broad-spreading and graceful branches of their North American parent, but their admirable performance would seem to be a reasonable trade off.
Today, 25 years after his initial introductions, and after much urging by friend and nurseryman Don Shadow, Orton has introduced C. ‘KF1-1’ (Saturn). Originating as a seedling cousin of the early introductions, Orton now believes that he may have initially missed one of the very best. Saturn’s upright vigorous growth, free flowering, and excellent staying power make it a winner to look for this spring.
Other new introductions from Dr. Orton arise from his incorporating the Pacific native C. nuttallii into his breeding program. ‘KN4-43’ (Starlight), a hybrid of C. kousa and C. nuttallii, offers four to six broad rounded bracts of creamy white. It is likely to be a better plant for the southern latitudes—think USDA Zone 6b and south—but its flower power is astounding. ‘KN30-8’ (Venus) maps out as three parts C. kousa and one part C. nuttallii, but however you describe it, the words stunning and stupefying might be considered appropriate. The parent tree measures 18 feet tall, 25 feet wide, and at flowering time every branch is absolutely covered with brilliant white blooms six to seven inches in diameter. Be careful not to plant this one in the front yard if you live on a busy street—unless you are in the auto body repair business!
NEW FLOWERING DOGWOODS
Even with all the attention paid to the hybrids these days, the new-plant world has not ignored the straight species. Over the last few years, the University of Tennessee has introduced several new selections that give Cornuphiles reason to wake in the morning. Cornus florida ‘Appalachian Spring’ hit the market a couple of years ago as the only dogwood anthracnose-resistant cultivar. Three other selections, ‘Jean’s Appalachian Snow’, ‘Kay’s Appalachian Mist’, and ‘Karen’s Appalachian Blush’, have been touted for high powdery mildew resistance. The first two have shown good resistance, performing at least as well as ‘Cherokee Brave’, a pink-bracted form that has served as the standard-bearer of mildew resistance in recent years. The last of this trio, though, has failed to live up to its billing.
Meanwhile, C. florida ‘D-383-22’ (Red Pygmy), another new Orton introduction, is destined to make a major splash in garden centers. Bred from an old white-bracted form, ‘Pygmy’, this new selection combines compact growth with tremendous crops of blooms of the deepest pink-red. A waist-high plant in our nursery at Yew Dell Gardens had more than 50 blooms each of the last two years!
The first to come out of Dr. Elwin Orion’s breeding program at Rutgers University, dubbed the Stellar series, these Cornus florida x C. kousa hybrids were a major innovation for gardeners facing dogwood decline. All grow 18 to 25 feet or taller, flower between C. florida and C. kousa, and show excellent hybrid vigor, outgrowing even the most energetic selections of either parent
‘Rutban’ (Aurora) Offers the best foliage of the group, with deep green summer color and a fall show of brilliant reds.
“Rutcan” (Constellation) One of the most vigorous of the Orton hybrids, this upright grower has large blooms of bright white, distinctly separate bracts.
Rutdan’ (Celestial) First introduced as Galaxy, this selection bears heavy crops of clear white rounded bracts that bend up at the midpoint to form a bit of a cup.
‘Rutlan’ (Ruth Ellen) Wide-spreading and early to bloom, with brilliant white bracts that often fade to pink as they age, it’s the Stellar closest to straight C. florida.
‘Rutfan’ (Stardust) Very wide spreading and low branched. It’s rarely seen in the trade because of graft incompatibility problems, but can be grown from stem cuttings.
Rutgan’ (Stellar Pink) Boasts the faint pink bracts of its C. florida ‘Sweetwater Red’ parent, but these can appear white some years. Regardless, this rounded plant is the most graceful of the lot.
‘KF1-T (Saturn) Not introduced with the original six, this may be the best of them all—a vigorous rounded grower with lustrous green summer dress and tremendous masses of overlapping white bracts.
For small-space gardeners, or for those who can’t possibly get enough saturation in their flower colors, this is a must.
NEW KOUSA DOGWOODS
They are naturally resistant to both dogwood anthracnose and powdery mildew, and they combine excellent foliage, summer flowers, autumn fruit, and exfoliating bark—it’s not surprising that C. kousa selections have been coming out fast and furious. Most of the best come out of seed of the variety C. kousa var. chinensis, which tends to produce plants of greater vigor, better summer and fall foliage, and heavier flowering. For the white-bracted forms, the best of the best would include ‘Greensleeves’, ‘Moonbeam’, ‘Blue Shadow’, and ‘Propzam’ (Prophet), the latter producing large crops of the most sweet-tasting fruit of any I’ve tested. Unfortunately for those who favor the pinks, most of these varieties are so confused in the trade that it is a true case of “buyer beware.” (The only selection that can be easily distinguished from the others is ‘Beni Fuji’—but it stands out for its small and narrow pink floral bracts and dense shrubby habit. Not exactly a stellar calling card.) Despite the confusion, most make good garden plants.
For those that tend toward the variegated world, C. kousa ‘Gold Cup’ from New Zealand, with its leaves of deep green with a brilliant gold central boss, has outpaced its close cousin ‘Gold Star’. The former seems to be the better grower and its foliage holds up even in full Kentucky-summer sun. If white variegation is more your cup of tea, the somewhat shrubby-growing ‘Wolf Eyes’ has been quite a winner, its creamy-edged foliage staying true in sun or shade in all but the deep South. The more free growing ‘Samzam’ (Samaritan) has put on an excellent show even in the full sun in Don Shadow’s fields in Tennessee. Together, these make excellent single specimens for just about any garden.
MORE TO WATCH
Possibly the most intriguing member of the C. kousa tribe is the closely related C. angustata ‘Elsbry’ (Empress of China). While certainly for the more southern climes, the glossy evergreen to semi-evergreen leaves, stupendous masses of creamy white bracts, and brilliant raspberry red fruit make quite a package. Probably best in Zone 7 and south—or maybe in Zone 6, too, for those interested in a little experiment.
Finally, in the quiet hinterlands of the North, the C. alternifolia clan has remained fairly quiet in recent years. About the only noise made in the past has been the white-variegated ‘Argentea’, and while excellent specimens can occasionally be found, their performance is generally less than outstanding. However, two new kinfolk are getting ready to make quite a splash. Cornus alternifolia ‘Wstackman’ (Golden Shadows) combines the typically graceful branching of the species with an exquisite margin of chartreuse on every leaf; C. alternifolia ‘Bachone’ (Gold Bullion) is a new yellow-leaf form that has the potential to be truly spectacular in a lightly shaded spot. Neither has received extensive testing yet, but I would venture a guess that no self-respecting mail-order hound will be without a trial of their own in the next couple of years.
For those in areas where dogwood anthracnose is a problem, this is a must-have. It was selected from Maryland’s Catoctin National Mountain Park where it was one of the very few survivors in an area where almost the entire population of native dogwoods was eliminated by the dreaded disease. This shows up under several similar names, but however you call it. it is definitely on my list of trees to bring along to my own private island.
This precocious bloomer is one of the more cold-hardy selections and has shown reasonable resistance to powdery mildew and stem canker.
Likely identical to what is in the trade under the name ‘Barton’.
One of the heaviest bloomers and most dependable performers, this introduction has shown excellent resistance to powdery mildew, stem canker and spot anthracnose in several studies.
Compact size, heavy bloom set on young plants, and intense red bract color make this one a must-have.
With all the newfangled variegated forms coming onto the market, this one has yet to be surpassed. Bright white marginal variegation on a gray-green field; occasionally bothered by spot anthracnose but not as bad as some others; sometimes sold under the name ‘Elegantissima’. Still one of the best for brilliant red winter stems.
Low sprawling form with bright yellow winter stems and variegated leaves of gray green with white along the margin. Will occasionally show some spot anthracnose on leaves.
A Harold Pellet selection that combines low, spreading growth, good red winter stems, and soft yellow summer foliage; full sun in the North and a light afternoon shade in the South.
Brilliant shades of red, coral and yellow, and light sulfur yellow fall color Older stems turn gray brown after just a year or so of growth, so this one needs lots of renewal pruning to keep it looking its best.
And for anyone planning something new for their garden this spring, the toughest decision to make may be how many other plants to remove to make room for more dogwoods. H For sources of plants featured in this article, turn to page 88. H