Download Dirr-Flowering and Evergreen Shrubs, An Alphabet Soup, Plant List

Flowering and Evergreen Shrubs:
An Alphabet Soup
Michael A. Dirr, Ph.D.
Copyright © 2014
Abelia―Abelia
Significant enthusiasm for A. ×grandiflora and cultivars with compact ‘Rose Creek’ among the
best. ‘Rose Creek’ and ‘Canyon Creek’ from my Georgia breeding program received the award of
garden merit from the Royal Horticultural Society. Twist of Lime™ (‘Aghop’) with cream-yellow
margined leaves is, to date, the most stable. Recently witnessed Twist of Orange™ with yelloworange tint to the new leaves. Attractive in a container but not sure of garden performance.
Twist of Lime™ held most leaves in good condition during the 2013-14 winter in our garden.
‘Kaleidoscope’, yellow/gold leaves, commands most market share. Radiance’ is a sport of
‘Kaleidoscope’ with white foliage margins. Currently, ~30 cultivars, mostly variegated, with
more on the way. Genus is being taxonomically rejiggered into four genera (Abelia, Zabelia,
Diabelia, Vesalea). Abelia chinensis, a parent of A. ×grandiflora, is larger in stature, with white
flowers throughout summer. Hardy to Chicago. Abelia mosanensis with pretty red-budded,
opening white, exceeding fragrant flowers has garnered attention. Performs better in cooler
climates. Fall color is a pleasing red. Plant introductions bred ‘Golden Fleece’ and Eternal
Sunshine™, the latter compact, with yellow emerging leaves, turning green and not burning in
heat. Abundant white flowers and pink sepals from May to November on a 2’ by 3’ plant.
Aesculus parviflora―Bottlebrush Buckeye
Noteworthy native with adaptability from Zone 4 to 8. White, bottlebrush flowers in late springsummer. Beautiful birch yellow fall color. Terrific shade tolerant shrub. No significant breeding
with buckeyes. Attempted to hybridize red buckeye, A. pavia, with A. parviflora to produce a
pink-flowered bottlebrush.
Berberis―Barberries
Invasiveness has tempered enthusiasm for this species. Still numerous NEW introductions with
‘Admiration’ with red-purple centers and cream to yellow margins on a compact framework,
quite eye-catching. ‘Daybreak’ is a yellow leaf selection with excellent heat tolerance and
orange fall color. Yet to set seed. From www.plantintroductions.com.
Red and yellow leaf cultivars are so abundant and indistinguishable that it is difficult to
pin-point the best. Spring Meadow has many new introductions in 2013.
University of Connecticut evaluated cultivars for fruit production. Lowest seed per plant:
‘Kelleris’ (6), ‘Aurea’ (5), ‘Bagatelle’ (2), ‘Antares’ (1), Crimson Ruby™ (0), and ‘Golden Devine’
(0). Continued evaluation showed all produce fruit. Sparkle had 35,300 fruits.
Buddleia davidii―Butterfly-bush
In and out of garden fashion like neckties. Resurgence with new colors, rose-red - ‘Miss Ruby’,
‘Miss Molly’; compactness – ‘Blue Chip’, ‘Lilac Chip’, ‘Pink C hip’; and total sterility - ‘Asian
Moon’. Trials at RHS Wisley, England, reflected visitors’ penchant for flower colors approaching
red with ‘Miss Ruby’ top vote collector.
Buzz™ Series from Thompson & Morgan are compact, 3 to 5’ high and wide. Flutterby™
Series from Ball Horticultural umbrellas ~15 cultivars. I consider ‘Blue Heaven’ among the best.
My Georgia program introduced eleven with ‘Attraction’ (red-purple), ‘Guinevere’ (deep
purple), and ‘Bicolor’ (lavender with butterscotch eye) the most popular.
Plant introductions and Bailey Nurseries will introduce Funky Fuchsia™, rose –red;
Groovy Grape™, vibrant purple, and Psychedelic Sky™, restrained blue, in 2014 through First
Editions®. All have been in the Dirr garden for two years and are terrific performers.
Noted a double-flowered, violet-purple hybrid that had the appearance of a doubleflowered African violet. First double I have observed. From Peter Moore, England.
Sterility is a large issue with Oregon banning cultivars that produce greater than 2%
viable seed.
Excellent web site, www.buddlejagarden.co.uk, with history, breeding and garden notes
on the genus. The author is a chemistry professor with an unbelievable passion for Buddleia.
Buxus―Boxwood
Voted number one shrub in a survey of 4,000 landscape professionals. See Nursery
Management 27(8):2011. All are green, some blue-green, functional, utilitarian, deer-resistant,
broadleaf evergreen shrubs. Observed no browsing in an Athens cemetery that is over-run with
boxwood and deer. Boxwood blight has created a stir. Currently, the U. S. National Arboretum is
assessing blight resistance and actively breeding for resistance. There is considerable screening
research in progress at North Carolina State University. What makes Buxus a fascinating
landscape plant is its adaptability from Maine to Florida. If it were taken out of the landscape
equation, there would be an unfillable void.
Callicarpa―Beautyberry
Numerous species known for metallic purple-colored fruits in fall. Energetic breeding by Dr. John
Ruter and Dr. Ryan Contraras, but nothing new materialized. Callicarpa dichotoma may be the
most cold hardy. All flower on new growth. ‘Duet’ is a cream-margined, medium-green centered
leaf, white-fruited selection that seldom reverts and does not scorch in sun/heat. ‘Early
Amethyst’ and ‘Issai’ fruit abundantly. Treat as cut-back shrub to stimulate vigorous shoot
growth. Callicarpa kwantungensis, with reddish purple new growth and purple fruits has
become available in the market.
Calycanthus―Sweetshrub
Great native (C. floridus) with sweet fragrance to flowers. Select ‘Michael Lindsey’, ‘Edith
Wilder’, ‘Athens’ (yellow) for guaranteed fragrance. Hybrids from North Carolina State include
‘Hartlage Wine’ (3 to 3 ½”, red-maroon flowers), ‘Aphrodite’ (similar but fragrant; although plant
in Dirr garden had no fragrance), and Venus™ (white, akin to star magnolia). They embody the
native species and C. chinensis, the Chinese species, with large, white tinged pink, non-fragrant
flowers. These hybrids are block-buster shrubs in flower! Venus™ is fickle with petal spot and
short-circuited life span (Dirr experience).
Caryopteris―Blue-mist Shrub
Overrun with cultivars but a worthy choice in sandy, well-drained soils, full sun exposure, for
summer into fall blue flowers. Flowers on new growth and has been hardy as a subshrub at the
Chicago Botanic Garden. Many yellow leaf and white-margined variegated cultivars. ‘First
Choice’ maintained erect, compact habit, deep blue flowers, and best foliage in Georgia trials.
‘Kew Blue’ and ‘Longwood Blue’ are worthy. Yellow foliage cultivars lose intensity in heat of
southeast. Certainly better in the north.
Ceanothus ×delileanus, C. ×pallidus
Blue and pink flowers on compact plants from old and new wood. Typically summer flowering.
‘Henri Desfosse’ (blue), ‘Gloire de Versailles’ (powder blue), and ‘Marie Simon’ (pink) prospered
in Georgia trials. Most are West Coast, Mexican species, but the above hybrids incorporate C.
americanus and C. herbaceus. Terrific breeding opportunities in this genus. Adaptable to Boston.
Ceanothus americanus, New Jersey Tea, is a remarkably disease-resistant, summer white
flowering, 3 to 4’ high native with adaptability from Zone 4 to 8.
Cephalotaxus―Plum-yew
Important Taxus, yew, alternatives where deer are problematic. Long dark green needles
separate them from Taxus. Cold (Zone 6) and heat tolerance (Zone 8-9), deer resistance, and
shade tolerance are attributes. Many cultivars with ‘Duke Gardens’, ‘Norris Johnson’, and
‘Prostrata’ leading the pack.
Chaenomeles―Floweringquince
Who cares? Old-fashioned, antiquated, creaky shrubs. Refreshing in winter-early spring in
myriad colors on naked stems. Dr. Tom Ranney introduced ‘Scarlet Storm’, ‘Pink Storm’, and
‘Orange Storm’, all with 1 ¾ to 2 ½” diameter, double flowers, fruitless, and thornless. Observed
abundant fruit on ‘Scarlet Storm’ in Oregon. New and time will arbitrate their greatness.
Estimated to 6’ high. Noticed leaves present in good condition in November (Athens) which is
not the norm for C. speciosa. At PII, sprawling habit in containers although advertised as upright.
Clethra alnifolia―Summersweet
Nifty native from Maine to Florida and Texas in moist to wet habitats. White, pink, to rose-red,
spicily fragrant flowers in summer. ‘Compacta’, ‘Sixteen Candles’, ‘Ruby Spice’ among the best.
Sugartina® (‘Crystalina’) and Vanilla Spice™ (‘Caleb’) are newer white-flowered selections.
Growing both and not particularly impressed. Larger than advertised. Both over 5’ in Plant
Introduction’s trials. Hybrid of ‘Hummingbird’ and ‘Ruby Spice’ with yellow-orange new growth
maturing to glossy dark green is intriguing. Has yet to flower. Perhaps in 2014.
Cornus amomum―Silky Dogwood
Cornus sanguinea―Bloodtwig Dogwood
Shrubby, stoloniferous to clump-forming rather aggressive shrubs. Discovered a red-stemmed
form of the typical purplish brown species C. amomum. Excellent orange-red fall color in 2011.
Cornus amomum is native to most of the eastern U.S. and grows into Florida. This red-stemmed
selection allows for successful culture in the South (and North) where canker is a problem on C.
alba and C. sericea.
Several yellow-orange-red stemmed C. sanguinea cultivars including ‘Anny’, Arctic Sun™
(‘Cato’), ‘Midwinter Fire’, etc. Beautiful in the winter landscape.
Cornus mas--Corneliancherry Dogwood
Cornus officinalis--Japanese Cornel Dogwood
Pretty yellow flowers appear on naked branches in March-April, sometimes as early as February.
C. officinalis flowers before C. mas yet the red fruits mature later in summer. Many cultivars of the
latter with ‘Aurea’, yellow foliage, and ‘Variegata’, white-margined leaves, among the prettiest. ‘Kintoki’
is a prolific flowering selection of c. officinalis. The fruits of C. mas are used in syrups, preserves and
jellies particularly in eastern European countries. Numerous cultivars have been selected for fruit
qualities.
Corylopsis―Winterhazel
Delightful yellow-tasseled flowers on naked stems dance to the yawning of a long winter. No
cultivar glut here but the species C. glabrescens, C. pauciflora, and C. spicata are all worthy.
‘Gold Spring’ (‘Golden Spring’) is a yellow leaf type of C. spicata. Needs shade in the South. Have
a compact, blue-foliage, soft yellow flower selection at PII.
Corylus―Filbert
‘Red Majestic’ and ‘Red Dragon’ with contorted stems and red-purple leaves provide year-round
interest. ‘Red Magic’ leaves turn green quickly. ‘Red Dragon’ displays complete resistance to
eastern filbert blight; 10 to 12’ by 6 to 8’. The latter hybridized at Oregon State University.
Cotinus coggygria―Smokebush
Have yet to add the species to the Dirr garden but am impressed with ‘Daydream’, ‘Dusky
Maiden’, and ‘Young Lady’. “Smoke” on the first and third smother the foliage. The middle has a
wavy-surfaced, bronze-purple leaf, smaller stature and resulted from C. szechuanensis × ‘Velvet
Cloak’.
Cryptomeria japonica―Japanese Cryptomeria
Many compact forms with Chapel View™, ‘Globosa Nana’, and ‘Gyokurya’ among the best.
Chapel View™ is derived from a witches-broom discovered at Duke University on a large
‘Yoshino’. Compact tear-drop shape and green winter color without the pronounced browning
that occurs on ‘Globosa Nana’ and others.
Daphne―Daphne
All are potentially wonderful, if they live! Fan of D. genkwa, Lilac Daphne, with lilac-colored
flowers. Unfortunately, not fragrant. Daphne ×transatlantica produces white, fragrant flowers
throughout summer. Hardy in Maine (Boothbay); performing well in Athens. Daphne odora is
the best choice for the South.
Diervilla―Bush-honeysuckle
A rather obscure native shrub with smallish yellow flowers in summer, bronze young shoots,
deep green at maturity, yellow to reddish in autumn. Principle asset is durability. Have grown
countless seedlings with several added to garden. Bonnie always . . . why? Cool Splash™ is a
white-margined, green-centered leaf selection. Holds variegation in heat. Prone to reversion.
Diervilla has been hybridized with Weigela.
Distylium―Isu Tree
Evergreen members of Hamamelidaceae with small red flowers in mid winter-early spring. Zone
6 adaptability with D. racemosum. ‘Blue Cascade’, ‘Emerald Heights’, and ‘Vintage Jade’ are
hybrids of D. racemosum and D. myricoides. ‘Vintage Jade’ grew 2’ by 5’ in 6 years and is being
successfully grown in Louisville, KY. Superb alternatives to cherrylaurels, hollies, and junipers.
See www.plantintroductions.com for in-depth information. New introduction is Coppertone™
with bronze-purple new growth, maturing to matt blue-green. Stunning when new leaves are
emerging. Estimate 2-3’ by 4-5’. Linebacker™ is an upright, broad columnar form with reddish
purple new shoots. Will reach 6 to 10’ by 4 to 6’. Both are Plant Introductions hybrids.
Distylium ‘Spring Frost’ has white young shoots that mature to green. Introduced by Greenleaf
Nursery in Garden Debut™ program.
Euonymus alatus―Winged Euonymus
Great red fall coloring shrub but invasive and listed as such in 21 states. Banned in
Massachusetts and New Hampshire. Yi Li, University of Connecticut, developed a sterile triploid
from endosperm tissue of ‘Compactus’. Not yet on market but a major advancement when
commercialized, if truly fruitless. According to the research appear, ~about 8 to 10 plants have
been recovered from the 3n endosperm tissue. I have observed that not all triploid plants are
sterile.
Fothergilla ×intermedia
Hybrids between F. gardenii and F. major are designated as such. ‘Mt. Airy’, introduced by the
author, gave Fothergilla an identity. Still the most common cultivar in commerce because of
reliable flower production and consistent yellow-orange-red fall color. ‘Blue Shadow’ from Gary
Handy, has glaucous blue leaves and is a sport of ‘Mt. Airy’. Beautiful summer foliage and similar
flowers and fall color to ‘Mt. Airy’.
×Gordlinia grandiflora
Remarkable semi-evergreen hybrid between Franklinia and Gordonia engineered by Dr. Tom
Ranney. Flowers, 3 to 4” across, open on new growth in summer-fall. Older leaves turn brilliant
red (purple). Shrub or small tree. Exceedingly fast, 5’ in a single season at PII. Easy to root from
cuttings. Requires excellent drainage and a degree of good cultural fortune. Estimate Zone 6 to
8.
Gardenia jasminoides―Gardenia
Worked on cold-hardy (Zone 6) breeding with Pinwheel™, a single, white, fragrant, 3’ by 3’,
performing well in Louisville. By degrees, the hardiest gardenia to date. Heaven Scent™ is
smaller in all characteristics and slightly less cold hardy than Pinwheel™. Both with single, 6petaled flowers in May-June, reblooming into fall. Breeding continues with a cold-hardy, doubleflowered reblooming selection, ‘Doublemint’, from PII, that flowers into November. Trying to
breed a pink flowered gardenia.
Hamamelis―Witchhazel
First order shrubs offering kaleidoscopic flowers from fall into late winter, brilliant fall colors,
and ironclad adaptability. ‘Wisley Supreme’, H. mollis type, with sweet-scented, yellow flowers
and spectacular yellow fall color is a beacon in the new Dirr garden. Numerous H. × intermedia
cultivars. Consider the native H. virginiana, with fragrant spidery yellow petals in fall and rich
birch yellow fall color. This species grows almost anywhere. ‘Lemon Lime’ has leaves speckled
yellow, light green, and green; delicately beautiful. Holds variegation in shade. ‘Harvest Moon’
and ‘Little Suzie’, 5’ by 5’, are worthy. New species. H. ovalis, discovered in Mississippi, is
stoloniferous with floral characteristics similar to h. vernalis.
Hibiscus syriacus―Rose-of-Sharon
Too many. Most so-so. Chiffon™ and Satin™ Series have merit. Impressed with Blue Satin™
(‘Marina’), a deep velvety blue-purple with red-maroon center. Species is back in fashion. Doug
Welty, who handles plant sourcing for QVC (TV), could sell 300,000/year. Everybody has new
cultivars. Need compact habits, a range of flower colors and sterility. See Bailey Nursery Spring
Meadow and Greenleaf Nursery for a cornucopia of new introductions.
Hydrangea (see separate handout; continually updated; estimate more new Hydrangea introductions
than for any other genus)
Hypericum―St. Johnswort
Four-hundred species. I’m confused. Believe the U.S. natives are worthy. Love H. densiflorum as
it grows in water (mountain tops also) with rich deep green, linear, fine-textured leaves that
turn yellow-orange in fall. Hypericum frondosum ‘Sunburst’ produces 2” diameter bright yellow
flowers contrasted with the blue-green foliage. Hypericum kalmianum Blue Velvet™ with smaller
¾” diameter flowers and glaucous blue foliage is worthy. At PII, Hypericum breeding is in high
gear, with seedling selections of Blue Velvet™ more compact and richer glaucous blue in foliage.
Cobalt-n-Gold™ is the first introduction from pii’s breeding.
Illicium―Anise
Fragrant foliage, shade tolerance, deer and pest resistance have endeared these evergreen
shrubs to Zone (6)7 to 9 gardeners. Illicium parviflorum ‘Florida Sunshine’ sports soft yellow
leaves. Plant Introductions has a new compact selection, similar to ‘Florida Sunshine’ in leaf
color but easier to root, grow and not as wild and woolly. New purple leaf type, ‘Purple Haze’, I.
anisatum, increases the color palette. ‘Pink Frost’ has white-margined leaves that turn pink-rose
in cold weather. A selection of I. floridanum.
Indigofera decora―Chinese Indigo
The genus is immense with as many as 700 species. This species grows 1 to 2’ high, spreading by
rhizomes/stolons to form large colonies. Pretty blue-green leaves, pink-rose flowers in 4 to 8”
long slender, arching-pendulous racemes. Flowers profuse in May; still chugging along in
October. In the new Dirr garden, this plant is subject to frequent queries. Indigofera kirilowii
grows slightly taller (3’) with bright pink flowers. Both flower on old and new wood. Estimate
Zone 5 to 7.
Kalmia latifolia―Mountain-laurel
Many beautiful flower colors from Dr. Jaynes breeding research. Not an everyday garden center
item. Buy Dr. Jaynes book and marvel at the variation.
Kerria japonica―Japanese Kerria
Can’t gain commercial traction. Early leafing and flowering (yellow), late yellow fall color, grass
green stems, sun and shade tolerance add up to a worthy garden addition. Have tried to find
fruits for breeding work without success. Help! Number of cultivars with variegated foliage
(‘Chiba Gold’, ‘Geisha’, ‘Picta’), large yellow flowers (‘Honshu’, ‘Golden Guinea’, ‘Shannon’), and
double flowers (‘Peniflora’). Variegated types will revert. Found a source of commercial seed
and have yet to produce a single seedling. .
Lagerstroemia―Crapemyrtle (see separate handout)
Lindera species―Spicebush
Yellow flowers on naked-stemmed (deciduous) and evergreen species. Beautiful narrow-elliptic,
dark green, glaucous below leaves turn yellow, orange, and red in autumn on L. glauca var.
salicifolia. Undemanding, sun and shade tolerant, withstands heat and drought, hardy to
Boston. Lindera obtusiloba and L. triloba produce delightful yellow fall color. Great shade
tolerance as a genus.
Loropetalum chinense var. rubrum―Pink Fringe-flower
Not a single clone until 1989; over 40 in 2014. Changed the market for purple leaf shrubs in Zone
7 to 9. Forget purple leaf barberries. Reddish purple leaves with degrees of staying power (color)
in South; pink, hot pink, to red flowers (Ever Red®) in spring. Sizes from 1 to 2’ (Purple Pixie®) to
25’ (‘Blush’). ‘Zhuzhou Fuchsia’ is the hardiest and I observed healthy plants in Cincinnati.
‘Crimson Fire’ is a new, compact-mounded spreading selection, 2-3’ by 2-3’, from Plant
Introductions, Inc. and licensed to Bailey Nursery in the First Editions® Collection. ‘Plum Cutie’
holds the purple leaf color in winter and has redder flowers than ‘Crimson Fire’; grows 2-3’ by 34’, from Plant Introductions and licensed to HGTV. Sparkling Sangria™ has red-purple leaves and
near red flowers, estimate 6-8’ by 6-8’, from Plant Introductions; also in first editions®. ‘Ruby
Snow’ has purple leaves and white flowers. Matures rather quickly to olive-green foliage.
Estimated to grow like ‘Zhuzhou Fuchsia’. ‘Ruby Lace’ has cream-pink-purple new leaves that
mature to purple, flowers are pink, perhaps not as vigorous as others but rather pretty when the
new foliage emerges. Garnet Fire™ (‘sPg-3-017’) with garnet-red flowers and deep maroon-red
leaves grows 4-5’ high. The last three were introduced by the Southern Plant Group and licensed
to Greenleaf Nursery.
Magnolia stellata―Star Magnolia
Many cultivars with ‘Centennial’, ‘Royal Star’, and ‘Waterlily’ among the best. Years past grew a
seedling population of ‘Centennial’. One proved spectacular with up to 56 tepals per flower,
pink in bud, fragrant, and strewn with numerous flower buds. 12’ by 6’. Bailey Nursery will
introduced in 2014 in First Editions® as ‘Centennial Blush’.
Nandina domestica―Nandina
Too many, yet still being introduced. Functional, tenacious, and resilient. Will always be a part of
Zone (6) 7 to 9 gardens. Blush Pink® (‘AKA’), Flirt™ (‘Murasaki’), and Obsession™ (‘Seika’) are
compact growers with emerging colorful reddish foliage. Led a plant tour of the Missouri
Campus, Columbia, in January, 2013. Nandinas everywhere. Who would have thought?
Osmanthus species―Tea-olive
Where adapted, Zone (6) 7 to 9, superb broadleaf evergreen shrubs with fragrant white flowers
in fall or spring. Sun, shade, heat, drought . . . they excel. Osmanthus heterophyllus is the
hardiest. New (2014) O. heterophyllus introduction, Party Lights, with pink new shoots,
becoming green white variegated at maturity. I was impressed at first glance.
Philadelphus―Mock-orange
Like Deutzia species, minimal to no interest from commercial growers, but fragrant, purpleeyed, white-flowered types like ‘Belle Étoile’ and ‘Sybille’ are outstanding. ‘Manteau d’Hermine’
(double, fragrant, 3 to 4’) and ‘Silver Showers’ (single, fragrant, 5 to 6’, refined foliage) are
garden worthy. With the repeat flowering trait, the plant would find commercial and greater
garden acceptance.
Physocarpus species―Ninebark
Observed many times in wild, always by water courses, but exceedingly well-adapted to drier
situations. Purple leaf types are numerous with Diabolo® (‘Monlo’) the first. Best in cooler
climates where foliage color is not diminished. ‘Little Devil’ and Summer Wine™ (‘Seward’) are
smaller. Burgundy Candy™ (‘Podaras 1’), Center Glow™, Coppertina™ (‘Mindia’), and Lady in
Red™ (‘Tuilad’) are additional purple-leaf types. ‘Ruby Spice’ has the deepest purple foliage I
have witnessed. More purple leaf types are on the way. Stay tuned. ‘Little Devil’ was a
disappointment in the Dirr garden. Lost most of the color in the heat.
Punica granatum―Pomegranate
Health benefits are touted! What about ornamental contributions? Pretty orange flowers in
summer, bright yellow fall color, full sun, drought tolerant. ‘Purple Sunset’ with orange flowers
and one-inch diameter shiny purple fruit grows 3 to 4’ high and is hardy in Zone 7. ‘Orange
Blossom Special’ is 2 to 3’ high and wide, extremely floriferous, with small apple red-green
fruits. Zone 8. Great choices for containers, annual beds, shrub borders. Prospers in full sun,
heat, and well-drained soil.
Rhododendron―Rhododendron and Azalea
Difficult genus to wrap one’s arms around. Current focus of breeding is REBLOOMING and the
Encore® azaleas, 29 strong, flower in spring, late summer-fall. Primary Achilles’ heel is minimal
cold hardiness.
Bloom ‘N Again® (10 cultivars, 3 to 4’ high and wide) and Bloom-a-Thon® blanket
evergreen reblooming azaleas from McCorkle Nurseries and Bob Head (Garden Debut®),
respectively. Both appear to have Satsuki genes. Bloom-a-Thon® is listed as Zone 6 to 9. [Double
Pink, Lavender, Double Red, Red (‘RLH1 1P2’ PP21,562), White; 2 ½’ to 4’ by 5’]. The Double Red
is a true red with lustrous dark green foliage. Quite impressive.
New reflowering introductions include include Rebloom® with 9 colors, and Always
Azaleas™ with 4 colors.
Southgate™ Series: Brandy™, Breezy™, Grace™, Divine™, and Radiance™, all with pink
white to lavender-purple flowers, have the heat tolerant R. hyperythrum as one parent. Zone 6
to 9 adaptable. Rhododendron hyperythrum habit and foliage remind of R. yakushimanum
without the velvety pubescence on the lower leaf surface.
Rosa―Rose
Oversaturation? Who knows the best? Knock Out® series continues to lead the race. Drift®,
Earth-Kind™, Flower Carpet®, Oso Easy®, Easy Elegance® are huffing and puffing to catch up. As I
pen this in November 2013, the original Knock Out® is still flowering with foliage to the base. For
those gardeners who do not spray, it is about as good as it gets. Home Run® (single red) is a
steady disease-resistant performer in the Dirr garden. Now a pink in the Home Run® series.
Sambucus―Elder
Black Beauty® (‘Gerda’) and Black Lace® (‘Eva’) with S. nigra genes are not comfortable in the
South. Best as cut-back shrubs in most gardens. PII is breeding with S. canadensis to enhance
heat tolerance. In my travels, have noticed many hybrids of Sambucus. Be alert. They are
possibly coming to a garden center near you. New cut-leaf yellow foliage type, Lemon Lace™, in
2014 from Proven Winners®.
Sarcococca―Sweetbox
Broadleaf evergreens with sweet cream-white flowers during winter-early spring. Ideal for shady
habitats. Sarcococca hookeriana and var. humilis (hardiest) are most common but S. orientalis
and S. confusa are better adapted in Zone 7 and 8. Nothing new except for two patented
cultivars from Sidhu & Sons Nursery, Canada. Both are 1 1/2 to 2’ by 3’. Listed as deer resistant. I
have grown seedlings of most species and experienced minimal variation. ‘Winter Gem’, a
hybrid, with red stems and lustrous dark green leaves, was released in 2014. In the boxwood
family and susceptible to boxwood blight.
Spiraea―Spirea
Another yellow leaf spirea. Please, no! The pure folly is a handful of seed from yellow leaf
cultivars produces numerous yellow leaf seedlings. Need one (1) that does not cook and discolor
under high heat and drought. About 36 yellow types described in 2009 Manual. Magic Carpet™
(‘Walbuma’) is one of best. Highest rating in RHS trials.
Several “old” species that I have grown in the various Dirr gardens include S.
cantoniensis ‘Lanceata’, Double Reeves Spirea, with blue-green foliage and terrific heat and
drought resistance. Also, S. thunbergii with March-April twinkling single white flowers, bright
green foliage, and yellowish tinged orange-bronze fall color. ‘Ogon’ (‘Mello Yellow’) sports soft
yellow leaves; the color persisting in the heat. Have contemplated breeding these iron-clad
types, including S. ×vanhouttii, for improved habit, foliage, and flower. In 2012, a large
population of ‘Ogon’ produced 75% yellow-gold seedlings in various sizes that did not burn in
the heat.
Stewartia―Stewartia
Foliage, flowers, fall color, bark―first class. Stewartia monadelpha, S. sinensis, S.
pseudocamellia, S. koreana are the most garden worthy. Can be frustrating for the nursery
grower and gardener. ‘Scarlet Sentinel’ is a hybrid of S. ovata × S. pseudocamellia, white flowers
crowned with red-pink (scarlet) stamens. Arnold Arboretum introduction.
Syringa―Lilac
~Twenty species and most disdain heat. What to do? Collect all and evaluate. Have done so at
PII with S. pubescens subsp. patula, S. pubescens subsp. microphylla, S. meyeri, S. × laciniata, S.
oblata and S. protolaciniata ‘Kabul’ superior. Open-pollinated seedlings and controlled crosses
afforded significant advances in reblooming traits. Bloomerang® (‘Penda’) is a rebloomer that
suffers in Zone 7. Improved performance in North but was barely flowering in early October in
Maine. A virtual unknown species for breeding heat tolerant lilacs is S. protolaciniata ‘Kabul’,
discovered in Kabul, Afghanistan.
The joyous dividends of this breeding initiative are lilacs for the South into north Florida
yet with Zone 4 hardiness, and reblooming. Plant Introductions, Inc., has over 100 reblooming
lilacs under evaluation with two currently in tissue culture.
In 2014, Plant Introductions had 1403 seedlings and selections on the ground. Our
breeding strategies were predicated on evaluating over 50 taxa that offered the greatest
promise of heat tolerance and longevity. All were outplanted in our test areas and only Josee™,
‘Red Pixie, ‘Lilac Sunday’, ‘Hers’, S. laciniata and S. meyeri, of the shrubby types, were alive as of
March, 2014. Syringa protolaciniata was not available until 2014, so was not field planted.
Vaccinium ashei―Rabbiteye Blueberry
Vaccinium corymbosum―Highbush Blueberry
Gardeners can have their pie and eat it too. Many worthy cultivars. Blue Suede®, Bountiful
Blue™ (‘FLX-2’), Summer Sunset™, and ‘Sunshine Blue’ (‘Blue Pearl’) are more restrained, selffertile cultivars, with sweet fruits and orange to red fall color. Blueberries are now the kings and
queens of retail garden center fruit sales.
Viburnum―Viburnum (see separate handout)
Vitex agnus-castus―Chastetree
Beautiful lilac, violet, blue flowers in large panicles, summer into fall. Flowers on new growth so
removal of spent flowers encourages new growth. ‘Shoal Creek’ rated best in Longwood Garden
trials. Need smaller habit in 5 to 8’ range. Breeding at the University of Georgia resulted in four
cultivars, all listed as 4 to 6’ high or less, with purple, pink and white flowers. Need good white,
pink to rose, and deeper blue cultivars. Plant Introductions has a more compact selection, Delta
Blues™ (‘Matt’s Blue’), with rich blue purple flowers. Grows to 8’. Seedling populations from this
have yielded many compact types. More enthusiasm for Vitex improvement in the past 10 years
than the previous 50. ‘Flora Ann’ is the deepest pink-flowered selection yet and supersedes
‘Salinas Pink’. Vitex negundo var. heterophylla, with incised leaves and greater hardiness might
be used for breeding with V. agnus-castus. Proven Winners released a new Vitex agnus-castus,
Blue Diddley™, that is described as a 3 to 6’ high ball of lavender blue.
Weigela―Weigela
A common eye sore in midwestern gardens. Perhaps the ugliest pile of sticks in the winter
landscape but numerous purple leaf and variegated introductions provide a new lease on
garden life. Yet to test any purple leaf types that hold color in Athens (Zone 7). Flea beetles have
done a number on ‘Spilled Wine’. Better in North. How many purple leaf types can a garden
stand?