Saturday, December 29, 2012

Damn good plants - Red twig Dogwoods, Part two

Part Two - Red-Osier Dogwood

Basket - Flickr, Marche Gluharche
The Red-Osier dogwood, Cornus sericea (syn. C.stolonifera) is North America's native answer to the Siberian Tatarian dogwood, Cornus alba.   Found growing from Alaska and east to Newfoundland, in any moist location.  The common name originated from its use in basket weaving and wicker work, where it was referred to as a red willow.  Willows are often called 'Osier's' and the name has become interchangeable between both dogwoods and willows.

The Red-Osier was prized amongst many native American Indian tribes for its use in an array of different purposes. The inner bark was processed and dried for mixing with tobacco in scared pipe ceremonies. It is said to have a mild, pleasing smoke that is not addictive like tobacco or causes any mood changes.  The Potawatomi people who live in the upper Mississippi river region, used the stems to make dream catchers and once used the feathered ends of its twigs as toothbrushes.  Just like the Tatarian dogwood, bows and arrows were popularly fashioned from its long, straight stems.

Apart from weaving, weaponry and dental hygiene,  red-osiers were also used for their medicinal benefits.  Infusions were made from the bark and used as an anti-diarrhea tonic by the Chippewa and Potawatomi tribes.  Shuswap's Indians also created antidotes for weak kidneys and pediatric tonics for children who wet the bed.  The Chippewa people used red-osier dogwood bark to make an infusion to ease blistering caused by poison ivy, one I need to look into.

Natural stand growing along a creek- Flickr, Meg Williams

People aside, wildlife also prize red-osiers for more than just cover to hide in.  The berries ripen in late summer and may persist on the plants well into winter.  The list of birds known to seek out the berries too long to go into any detail but I have included a link at the end of this post for more reading.  The twigs and foliage are valued for nourishment by our four footed gardening friends , much to the disdain of any gardener, unless your goal is to attract wildlife.  This includes many american iconic animals that include, black bear, beaver, raccoon's  skunks and of course deer!  For some other lucky gardeners you can also include elk, mountain goat and the mother of all foragers, the moose.  Do not despair, red-osiers are able to overcome heavy browsing and bounce back quickly to its former glory.

'Arctic Fire' - Proven Winners
However, the reason for this post is to highlight its great value as a garden shrub and many fine varieties have been selected for their ornamental characteristics.  Just like the Tatarian dogwood, it doesn't favor heat or humidity of the south, but instead prefers colder locations more to the north.  Those of us who live in zone 7 should be good but any further south could be problematic.

Below is a list of varieties that have found there way into the garden center and succeed well..  As you'll see, there just as diverse as the last group, offering many different choices for the landscape.

'Arctic Fire', (Farrow)  is a compact dwarf, non suckering form that makes it ideal for smaller gardens.    Unlike most red-osiers that can grow to 8 ft, this one will stay around 3-4 ft.  The dark ruby red stems glow all winter, providing a welcome treat after other plants have faded out.  In spring, fresh green growth covers the stems and allows emerging perennials to use its form as a backdrop.

'Cardinal' - Flickr, Glossaria
‘Cardinal’ by far is one of my favorite variety on the market.  The stems ignited the winter landscape with its fiery red coloration, but in southern locations the stems can take on a yellow to orange tone giving them the appearance of a blood twig dogwood.  The dark green foliage also turns a rich purple-red in fall, alerting people to its presence before revealing its grand show.  Somewhat more disease resistant then others, this variety can grow tall to 8 ft, but manageable with pruning.

'Isanti' is a good, reliable, compact grower to 5 ft with a neat and full habit.  Its growth fully covers the stems all the way to the ground so doesn't need landscaping in front to hide of its naked ankles like other shrubs.  This makes a good choice for screening or hedging.  Its main use is in reclamation work, where its fibrous roots and spreading habit is good for retaining soil on highway embankments in the north. Not a glamorous job description  but nevertheless a beauty when seen in mass, naturalized on the side of the highways or our own backyards.

'Kelseyi' -
'Kelseyi' was until recently, one that I always skipped over, favoring other dwarf types instead.  However, this year I ordered some in for a customer and was smitten by its character.  Now firmly on my wishlist of my own garden for 2013.  Its small and compact (2-3 ft) habit makes it s good choice for mixing in the front of borders, tucking it in with perennials.  During the winter, when the perennials go dormant and disappear into the ground, 'Kelseyi' will carry the show with its bright red stems until spring thaw awakes the garden again.

'Silver and Gold' is a variegated sport from the yellow twigged 'Flaviramea'.  Originating from the famous gardens of Delaware's Mt. Cuba, this variety showed better adaptability to heat and humidity of the mid-Atlantic region.  The bold creamy white leaf margins stand out in summer, but is replace in the fall by striking lime-green to yellowed stems.  The variegation is similar to C.alba 'Elegantissima' or 'Ivory Halo' as discussed in the previous post, making a good choice for those looking to combine red and yellow stemmed dogwoods.

Cultivation of Red-osiers is no different to that discussed before with Tatarian dogwoods.  Both types need to be reduced periodically to regenerate young growth that contain the best color.  Spread can be controlled by cutting back suckers or root pruning with a spade to prevent the spreading, stoloniferous shoots.  Though tough as old nails in the landscape, some disease issues can be problematic here in the south.  For me, a common problem is bacterial leaf spot and stem blight.  Making sure they have good air movement around the plant in summer and preventing irrigation systems from getting the foliage frequently wet will largely reduce the disease risks.  Thinning out the old and congested growth will improve air circulation as well as regenerating the plant again.  As always, prevention of fungal or disease attacks is better than treating once you contract it.  Spraying after the fact will only help prevent the spread onto new growth and not necessary turn around infected areas.

In the last part of this three part series we'll delve into one of the most striking types in the winter, the bloodtwig dogwoods.  So until then, I hope that you've been bitten by the allure of dogwoods to the point of planting one for yourself.

For more on Red-osiers click here:

Part One - Tatarian dogwoods
Part Three - Bloodtwig dogwoods

Wednesday, December 19, 2012

Damn Good Plants - Red twig Dogwoods, Part One

Part One - Tatarian Dogwoods

Nakedness is something you don't often think of when gardening.  Not that I'm advocating naked gardening, time is cruel, and my mental image of myself is far from reality.  Instead, I'm talking about the beauty uncovered when plants shed there robes of foliage, as in the case of red twig dogwoods.  At this time of year, Red twig dogwoods morph from a fairly unassuming shrub into a thing of wonder as their foliage drops to show off their fiery red stems.  No longer a background shrub, it comes out of its cocoon to grab the attention of the observer, changing a dull winter into a festival of color.

Berries - Flickr, Webeyer
There are three types of dogwoods known for their show of vivid colored stems during the winter.  Cornus alba, the tatarian or siberian dogwood, Cornus serica, the redosier dogwood and Cornus sanguinea, the blood twig dogwood.  The first two are fairly similar in growth and can be hard to distinguish apart when viewed by the average eye.  Even for myself, the differences are so slight that I don't concern myself with the technical side but instead focus in on the aesthetics of what it can provide. The blood twigs on the other hand are quite striking and fairly easy to identify.  Each group has its benefits, and in the interest of doing justice to each, I've broken the post into three parts so we can discuss them fully.

The tartarian dogwood can be found from Siberia, down to northern China and into Korea, growing on moist, boggy locations.  The common name 'Tatarian', is from of the ethnic group, Tatar, that live in the same area where this dogwood is common.  The first plants to be grown outside of their range were recorded being sent to  the Chelsea Physic Gardens in 1741, but was never admitted into the garden on account of its rampant spreading behavior   However smaller, well mannered varieties were produced from that first introduction that did make it into western gardens.

Stooled shoots - Flickr, Basswulf

Historically, the stems of this dogwood have long since been used in weaponry with arrow shafts found dating back to the Mesolithic period.  Its wood is extremely hard and has also been used for making cooking skewers and pipes to name but a few.  Some reports also refer to its use in gunpowder.  Charcoal, base ingredient  made from dogwood stems is considered the best for small-arms powders.  Dogwood charcoal was found to burn more rapidly than other woods, producing a stronger explosive to propel a round. Production of wood for charcoal processing could be done annually in a process called 'stooling' or 'coppicing' , where stems are cut down to its base in late winter.  The plant would then regenerated its growth and be ready for harvest the following year, something that is impossible to do with tree type dogwoods.

Below is a list of the varieties that I have seen come through the garden center during my time here.  As you will see, the Siberian dogwood comes in many different forms making the selection process harder when deciding which one to use in your garden.

'Argento-marginata' - Flickr,
'Argento-marginata' or also known more commonly as 'Elegantissima', is one of the most popular variegated forms in the market.  The cream white margin on the pointed leaf makes for an attractive show during the summer months.  It is a large specimen, growing upto 6-7 ft but less vigorous than the species.  Like others within the group this is very controllable with pruning   Fall color has a rosey red to add to its already interesting variegation but after leaf drop the vibrant red stem shine all winter long.

'Ivory Halo' (Bailhalo) is a more compact and densely branched form than the one mentioned above, to come out of Bailey's Nursery in Minnesota.    Making it a top pick for a smaller garden, this cultivar has become the one of choice for both landscapers and homeowners alike.  Apart from the reduced height, all other traits are the same as 'Elegantissima'

'Buds Yellow' - Flickr, tobchasinglight
'Buds Yellow', not as widely used as the variegated form, 'Buds Yellow' offers yellow stems instead of the normal red seen in the species.  Considered far more superior to our own canker disease prone C.sericea 'Flaviramea', this yellow form shows well when highlighted against snowy ground.  When combined with red stemmed dogwoods, the effect in the winter garden can be very dramatic.

'Aurea' - Flickr, CiaranBurkeGardenPic
'Aurea' and 'Prairie Fire' appears to be one of the same, both displaying a solid golden leaf.  By summer, the color softens to a lighter yellow on the outer branches, but more chartreuse green towards the interior.  Fall color fires up to a brilliant red before shedding.  The stem color is a rich flaming orange-red in winter.  With a range of attributes it's easy to see how versatile this variety is in the garden.

'Red Gnome' (Regnzam) is an extremely compact and low growing form (3 to 4 ft high, 4 to 5ft wide) suitable for any garden.  The slender green leaves turn a deep ruby red during the fall and give way to slender, upright red stems in winter.  Its height and compact habit makes it useful for hedging.

'Sibirica' - Flickr, Brianpettinger
'Sibirica' is a confused type, often being found named 'Westonbirt' or even as a different species called C.atrosanguinea.  Either way this is still the most popular red stemmed type in production today.  Foliage during the summer is a straight green and displays good fall coloration.  For anyone considering mixing yellow twigs with a red type, this would be the one to use as foliage color is the same.  The coral red stems appear to be more upright and the berries are blueish instead of the normal white, common for the rest of this group, which may of lead to the confusion over its naming.

The Siberian dogwood is somewhat an easy growing plant that doesn't require anything special to prosper.  It will tolerate wet locations and periods of drought once established and can take sun to partial shade.  Young stems produce the best color, so in early spring cut back 1/3 of its growth within 6 to 12" of the ground to encourage new growth.  These stems will shine the brightest in the landscape over the following winter until the next 1/3 to reduced back and allowed to regenerate.

In part two, we'll take a close look at our own red twig dogwoods and highlight some of the top varieties that have emerged from that group.  I hope I have intrigued you to stick around to see why a dogwoods bark can really lead to a bite!

Part Two - Red osier dogwoods
Part Three - Bloodtwig dogwoods

Wednesday, December 12, 2012

Damn Good Plants - Mahonia x media 'Winters Sun'

For us at the garden center, Thanksgiving marks the end of the garden shopping calender.  The customers switch gears from working outside in the garden to hanging swags and trimming the Christmas tree. But, for a few who venture out into the quiet shrub sales area, you'll be greeted by the blooming event of Mahonia's.

Often overlooked during the growing season, mainly because of its prickly holly like leaves, Mahonia's put on a show of bright sulfur yellow flowers that sprays out like water from a fountain.  Though missed by fair weather gardeners, die hard types still looking for horticultural fix, get to benefit from this explosion of color.  While the blooming season is magnificent, its habit and display of whorled frond-like foliage, makes for a year round, stately statuesque presence in any garden.

The Mahonia family contains about 70 species often found in woodlands from the Himalayas, to East and Central Asia and into the America's.  Commonly referred to as Grape Hollies, the blue-black semi-edible berries hang in clusters after flowering.  Related to Barberries, Mahonia's have a bright yellow inner bark that contains an alkaloid called Berberine, which is responsible for the color.  The colorant has long been used to dye clothing, wool and leather but is now being studied for its potential medicinal use in reducing cancer growths, lowering cholesterol and over coming insulin resistance.

Mahonia x media (media - meaning middle, or between, referring to the mix of two parents) was a result of a accidental cross between Mahonia japonica and Mahonia lomariifolia that occurred naturally.  Slieve Donard Nursery in Co. Down, Ireland was the birthplace of Mahonia x media, starting in 1952 with the discovery of seedlings showing slight foliage variations.  Six of the seedlings were selected for planting by Sir Eric Savill, who at the time was Director of Forestry to the crown estate of Windsor Great Parks, in England.  When these seedlings began to flower in 1957 it became evident that they were different from what the parent plants were.  The first seedling to make it to market was named 'Charity',and can still be found to this day at Savill Gardens.

'Winters Sun' came from the same linage as 'Charity' and became registered in 1966 after it showed a greater dense, compact growing habit when compared to others in the 'x media' group.  The bright yellow flowers also have a better fragrance, an added benefit for any early winter garden.   I have seen 'Winters Sun' flourishing in an unprotected, full sun location with little sign of stress, provided it has good access to moisture during the hot summer months.  However, all Mahonia's would favor the filtered sun of a cool, woodland garden.  Once established, they can tolerate drought for an extended period with little consequence.   In my garden, it has proved successful in deterring kids from jumping the fence looking for a short-cut around the neighborhood.   Apart from that, it also works well on deer that also dislike it presence.  Growing to a large 8 to 10 ft vase shaped form, it requires little pruning, though some stems can be reduced back after flowering to encourage a shorter, bushy habit.

I have read some comments about Mahonia's needs to cross-pollinate to produce berries, though doesn't seem to be mentioned enough to draw a strong conclusion.  It would still be advisable to include another specimen of its own species or one of a compatible species to ensure berry set.  One reference I read highly recommended our own native Oregon Grape Holly, Mahonia aquifolium, a beautiful, lower growing species, as a suitable partner for Mahonia x media.

Both 'Charity' and 'Winters Sun' are guaranteed to provide season round interest.  Their architectural presence and explosion of color will anchor them as a focal point from which to design other combinations from.  While it's not a shrub that will hug you back should you have the urge to show it some affection, it will grow into a loyal work horse of the garden, commanding respect while extending the season of interest, well into early winter.