Thursday, February 23, 2012

Green and Gold in the Garden: Aucuba and More

Nothing is quite as cheerful as the combination of green and yellow in the garden, especially this time of year when everything is looking rather ragged.

Himalayan Pine 'Zebrina' has yellow and blue-green needles.

Euonymus fortunei 'Moonshadow'
I’m lucky enough to walk past this charming Aucuba every morning on my way to work.  It has been particularly lovely over the last few weeks as Daffodils have slowly emerged at its feet...  first as dark, blue-green foliage, then in bud and now with sulphury yellow trumpets.

Commonly known as Japanese Laurel or Gold Dust Plant, Aucuba is a slightly rounded, evergreen shrub originally from Asia.  It grows easily in Zones 7 to 10 and will survive, if not prosper, further north.  I’ve always loved the tropical quality of Aucubas with their large glossy green leaves that seem to be splattered with golden yellow paint.  But there are varieties with almost solid green foliage.  All are cultivars of Aucuba japonica, which produce miniscule purple flowers.  Female plants will also yield clusters of small red berries if a male plant is grown nearby.

Aucuba definitely prefers lightly shaded, protected spots in the yard.  Too much sun or winter wind can weaken specimens, leaving them susceptible to fungal diseases and nematodes.  Aucuba responds well to pruning, so just cut back any damaged foliage and shape the shrub in the spring.  Don’t over-fertilize, over-mulch or add too much organic matter to the soil when planting.  Aucuba actually thrives as an understory or foundation plant in urban and seaside gardens and, once established, is drought-tolerant.  Most Aucubas eventually reach about 7’ tall by 5’ wide in Central Virginia.

This beautiful Aucuba inspired me to seek out other examples of green and gold brightening our landscapes right now, and I found… an absolutely perfect Winter Daphne or Daphne odora.

The dark rose-pink buds open into much softer pink blossoms.
This particular cultivar is called ‘Aureomarginata’ for its yellow-bordered leaves.  The color combination is a creamier, calmer version of Aucuba but is just as effective at illuminating a shady corner.

Daphne includes several species of small, rounded shrubs, mostly native to Asia and Europe.  Daphne odora is known for its dark pink buds that blossom into amazingly scented, pinkish-white flowers, at the end of winter.

I’ve never grown Daphne odora myself, because I really don’t have a good spot for it.  It definitely needs partial shade; something that mimics an open woodland with very little root competition; well-drained, fertile soil and regular moisture.  It also grows fairly slowly and struggles if transplanted.  Difficult, I know.  ‘Aureomarginata’ is supposed to be less temperamental.  And it’s so very sweet, both in appearance and fragrance, that I am tempted to try growing it in an enormous planter surrounded by Hellebores and Cyclamen.  Perhaps near my basement door where it would be shadowed by the house and I could enjoy it every day.

I also discovered these stunning variegated Boxwood or Buxus sempervirens.  This particular cultivar is called ‘Aureovariegata’ for its dark green leaves edged in pale yellow.

I know some gardeners have a love-hate relationship with Boxwood.  But I am fan.  Boxwood bring back memories of childhood visits to old Colonial gardens... the play of light and shadows, the musky scent, the sound of crushed oyster or pebble paths.  Boxwood come in a wide range of luxurious green foliage, which bestow a sort of visual calm in any landscape.  Variegated cultivars provide subtle excitement.
Buxus sempervirens, also known as Common or American Boxwood, performs best in partial shade in Zones 6 to 8.  (Mine grow in direct, morning sun, which means they bronze a lot in the winter.)  It prefers a slightly sweet, neutral soil, pH of 6.5 to 7.2, and its shallow roots don’t like to be over-mulched or over-watered.

Like all Boxwood, ‘Aureovariegata’ is evergreen and does flower in spring with the tiniest yellow-green stars.  It is slow-growing and responds well to shearing, but ‘Aureovariegata’ can eventually reach 8’ tall by 6’ wide.  These particular shrubs have been shaped into rather fat pyramids.  Gorgeous!

Luckily, we live close to one of the best Boxwood growers in the East.  Saunders Brothers is a third-generation family business that supplies shrubs, fruit and ornamental trees, perennials and annuals to nurseries and landscapers throughout the Mid-Atlantic.  They initiated and coordinate The National Boxwood Trials to assess Boxwood performance in various habitats throughout much of the U.S. and even in other parts of the world.  You can view the 2011 Report on their website, which is a great resource for anyone who currently grows or wants to grow Boxwood.

Saunders Wholesale Nursery is open to the public three times a year.  And they maintain a retail Farm Market from spring to autumn.  If you don’t have room for Buxus sempervirens ‘Aureovariegata’, the Saunders family recommends B. sempervirens ‘Elegantissima’, which is beautifully variegated but remains only about 2’ round.

A much smaller example of green and gold is Acorus gramineus ‘Ogon’.
Commonly called Sweet Flag or Japanese Rush, Acorus gramineus is an ornamental grass native to Asia.  ‘Ogon’ is literally striped bright green and yellow and its foliage remains evergreen in Zones 5 to 11.  The colors are especially vivid on new growth.  Sweet Flag loves moisture, light shade and organically-rich, almost-muddy soil, so I’ve planted it around one of my rain barrels where it can regularly catch overflow.  But several books recommend adding Acorus to mixed container gardens.  And I’ve transplanted rhizome divisions to much drier parts of the yard… still softly-shaded, but much, much drier.  I just water these younger plants by hand during the hottest part of the summer.
Acorus sends up citrusy-yellow flower spikes, or spadices, in summer.  These spikes are nestled among the strappy leaves, unlike well-known plants, such as Jack-in-the-Pulpit and Peace Lily, which protect each spadix with a curved spathe or hood.  Acorus grows about 10” tall and will continue to spread if happy.

And finally, I found a Hamamelis, or Witch Hazel, and Cornus mas, or Cornelian Cherry, in full bloom.

To be honest, I’m not sure if this Witch Hazel is Hamamelis virginiana or H. mollis.
Both species are large deciduous shrubs with open branching, essentially understory trees, that grow well in partial to full sun, in Zones 5 to 8.  Each could eventually reach 20’ tall and 15’ wide.  Witch Hazels are famous for their spicily-aromatic blossoms that look a little like clusters of ribbon or funny mop-heads and bloom in late winter.  Depending on the cultivar, flowers range in color from yellow to peachy-pumpkin to brick red.
Hamamelis x intermedia 'Diana'
H. virginiana and H. mollis sport bright sunshine-yellow fringe with purple-brown centers.  These Witch Hazels provide year-round interest in the garden.  In addition to early, fragrant flowers, they produce little brown berries that attract wildlife, have distinctive, smooth gray bark and turn brilliant colors in the fall.  Hamamelis virginiana is native to moist woodlands of eastern North America.  As you probably know, Witch Hazel astringent is made from an extract of its bark and twigs.  H. mollis is native to similar habitats in China.  Its leaves are more silvery-green.  Both species can handle heavy clay soil.

Cornelian Cherries are related to our native Dogwoods but originate from Europe and Western Asia.  They develop into large, upright shrubs, either grown with multiple stems or trained to a single stem… a small ornamental tree, really, that can reach 25’ tall and 15’ wide.  They enjoy sun to partial shade in Zones 4 to 8, and both the plant and its blossoms are exceptionally hardy, hence the mas part of the botanical name.
Cornus mas provides so much pleasure.  It is one of the earliest bloomers in the garden.  The tiny trumpet flowers cluster on bare branches, rather like old-fashioned chenille pom-poms, and are more primrose in color than those of Hamamelis.  Its summer cherries mimic small, red coffee beans and are delicious cooked in desserts or preserves… if you can get to them before the birds and squirrels.  It comes into leaf early, and foliage remains green well into the fall, before turning a muted, purple-red.  Some cultivars even have variegated foliage.  And its grayish, exfoliating bark creates a lovely winter silhouette.

Perfect, right?  The main problem for me is that Cornus mas and all Hamamelis require space I just don’t have.  In my small city plot, I contend with close power lines, adjoining houses and municipal right-of-ways and these shrubs would never reach their full potential.  But imagine them in a suburban garden with a backdrop of evergreen hedges for a beautiful scene of green and yellow at the start of every year.

Oh, and in case you were wondering, it is
Aucuba as in…
Ah-KOO-bah   (like Aruba with K in place of R).
The emphasis is on KOO.
Some folks say Ah-KEW-bah (like a cue ball with H instead of LL).

Daphne as in…
DAF-knee        (like a combination of Daffy Duck and knee).
The emphasis is on DAF.

Buxus as in…
BUCKS-us        (like male deer and us).
The emphasis is on BUCKS.

Acorus as in…
ah-KOR-us      (just like a chorus of angels).
The emphasis is on KOR.

Hamamelis as in…
ham-ah           (like gamma with H instead of G)
MAY                (the very merry month)
lis                   (like lisp without a P).
The emphasis is on MAY.

Cornus as in…
KOR-nus          (very much like cornice).
The emphasis is on KOR.

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