Plants

Working at the nursery as long as I have, there aren’t a lot of landscape plants suitable for Nantucket that I’m not familiar with, so I’m always pleased when I have the opportunity to learn something new.  Last fall, a customer asked about sea buckthorn, a plant I have absolutely no experience with.  After a little research, I think it might be a useful plant for some of the islands’ challenging sea-side properties.  We brought some in for a job this spring, and decided to order some extra for stock.  This plant should be a good choice for growing in close proximity to the shore, where soils are extremely sandy, drainage is excellent and sun is plentiful.

Hippophae rhamnoides has abundant grey/green, skinny leaves on thorny, branches.  Their habit is variable, sometimes reaching the size of a small tree, but they often treated as rangy shrubs.  The plants I have seen growing on Nantucket look quite a lot like Russian olives, although spinier and with narrower leaves.  These plants are dioecious, meaning that there are separate male and female plants.  If female plants are pollinated by males, they will have an abundant fruit set of small, yellow/orangy berries.  Native to the Northern regions of Europe, Asia and North America, sea buckthorn it is extremely cold hardy and can be expected to survive during prolonged periods of extreme cold.

There are many varieties in cultivation.  We’re currently stocking ‘Chuysaka’, ‘Hergo’ and ‘Juliet’.

I’ve spent many, many hours on ladders and on top of roofs and pergolas as a professional gardener on Nantucket.  The bulk of those hours have been spent on rose care, but pruning and training wisteria is actually one of my all-time favorite garden tasks.  This graceful, spring-flowering vine requires a lot of work to keep in bounds and looking its best.  This is especially true of the Asian varieties, which are quite a bit more rampant than their North American cousins.  Although there are many cultivars and hybrids, Asian wisteria can generally be separated into to groups: Japanese and Chinese.

Japanese Wisteria, Wisteria floribunda

Flowers open over the course of days, starting at the top of the cluster.  Tendrils twine counter clockwise.

‘Black Dragon’ aka ‘Violacea Plena’ aka ‘Yae Koburyu’:  Deep purple double flowers

‘Domino’ aka ‘Issai’:  Lilac blue flowers

‘Lawrence’:  Pale lavender flowers

‘Longissima Alba’ aka ‘Siro Noda’:  Long white flowers

‘Snow Showers’:  White flowers

‘Honbeni’:  Pink flowers

Chinese Wisteria, Wisteria sinensis

Flowers tend to open all at once.  Tendrils twine clockwise.

‘Blue Moon’:  Bicolor blue flowers

‘Caroline’:  Very fragrant, bluish purple flowers

‘Cooke’s Purple:  Fragrant, bluish purple flowers

‘Jacko’:  Selection of Alba; very fragrant, white flowers

‘Prolifica’:  Bluish violet flowers

‘Royal Purple’:  Deep violet flowers

If you’re interested in how to prune these vines, check out our articles and Youtube videos on the subject:

Video – Summer pruning of Wisteria

Video – Winter pruning of Wisteria

Article – Summer Pruning How-to

Article – Winter Pruning How-to

Having been a gardener and nurseryman on Nantucket for over 20 years, I’ve amassed a long list of favorite plants.  From year to year, the list changes as some plants become over-used and improved selections and exciting introductions hit the market.  Nonetheless, there are a few plants that will have a special place in my heart no matter what.  Old-fashioned lilacs are one of those.

When I was a child, my grandparents, Jim and Isabelle, had some common lilacs in their yard in Antigonish, Nova Scotia.  Fully mature, their stems had widened into trunks and they were so tall that we called them “lilac trees”.  Grandma would send us outside with kitchen scissors to cut the flowers and bring them indoors.  There were always extra to share, and we often brought some home to my Mom for our house too.  I also clearly remember Mom sending me down to our neighbor Theresa’s house to ask for a cutting of her lilac shrub.  We planted it at the edge of the lawn.  That lilac is now taller than I am and a lovely way to remember Theresa, who so kindly gave it to us, thirty years ago.

There are currently twelve species in the genus Syringa but only a few are cultivated in North America as garden plants.  Syringa vulgaris, common lilac, is the plant that comes to mind when most of us think of traditional lilacs.  There are many cultivars available, with flowers that range in color from crisp white, to deep purple-red.  There also numerous hybrids on the market that make great garden plants.  These lanky, suckering, shrubs grow 15-20 feet tall and can easily spread to occupy a space of 5 or more feet wide.  In order to keep lilacs looking their best, they do require a good pruning regimen.  Since the flowers appear on old wood at the tips of the branches, they can stretch out of reach as the plants get older.

Pruning is best done just after the flowers have faded in mid summer.  Keep in mind these objectives, while pruning:

• Remove diseased or damaged wood
• Encourage strong growth at the base of the plant, in order to combat the leggy habit
• Keep the height of the plant in check, so that flowers can be enjoyed
• Remove spent flowers, if desired

Consider following these steps while pruning:

1. Take a good look at the overall structure of the plant.  Consider removing one or two of the oldest stems completely, at ground level
2. Consider removing a few wayward branches
3. Make several cuts at different levels to encourage new, bushy growth throughout the plant.
4. Remove dead heads, making pruning cuts just above healthy buds.
5. Assess the overall height of the plant, and make deeper, staggered cuts to reduce the height.

Check out our pinterest board for photos of old-fashioned lilacs we’ve carried in the past:

https://www.pinterest.com/surfhydrangea/luscious-lilacs/

Here’s a quick reference guide to varieties we’ve had in the past:

Syringa vulgaris aka common lilac:  Light purple flowers.  10-12′

Syringa vulgaris ‘Adelaide Dunbar’:  Deep purple buds open to double paler purple flowers.  French lilac.

Syringa vulgaris ‘Agincourt Beauty’:  Very large, deep purple flowers. 10-12′.

Syringa vulgaris ‘Charles Joly’:  Deep purple, double flowers.  8-10′.

Syringa vulgaris ‘Edward J Gardner’:  Light pink, double flowers.  8-10′.

Syringa x hyacinthiflora ‘Equinox Valley’:  Reddish-purple buds open to double light purple flowers.  8-15′.

Syringa x hyacinthiflora ‘Maidens Blush’:  Light pink flowers.  Canadian lilac.  Early flowering.  10-12′.

Syringa vulgaris ‘Madame Lemoine’:  White, double flowers.  French lilac. 15′.

Syringa vulgaris ‘Monge’: Reddish-purple flowers.  French Lilac. 8-12′.

Syringa x hyacinthiflora ‘Mount Baker’:  White flowers.  Canadian lilac.  Early flowering.  12-15′.

Syringa vulgaris ‘Nadezhda’: Double, lilac-blue flowers.  Mid-season. 8-12′.

Syringa vulgaris ‘Krasavitsa Moscovy’ aka Beauty of Moscow:  Very pale pink buds open to double white flowers.  12′.

Syringa vulgaris ‘Lavender Lady’: Light purple flowers.  12′.

Syringa vulgaris ‘Paul Thirion’:  Reddish-purple buds open to double pale purple flowers.  French lilac.  10-12′.

Syringa x hyacinthiflora ‘Pocahontas’:  Deep purple buds open to paler purple.  Canadian Lilac.  Early.  10′

Syringa vulgaris ‘President Grevy’: Violet-blue, double flowers.  French liac.  10-12′.

Syringa vulgaris ‘President Lincoln’:  Purple-blue flowers.  Mid-season.  8-10′.

Syringa vulgaris ‘Sensation’:  Reddish Purple florets, tinged in white.  French lilac.  Mid-season. 10-12′.

Walking around the nursery yesterday, I couldn’t help but notice the overall lack of color.  With so many deciduous trees on site, you would think we would have a riot of red, purple, orange and yellow leaves all over the place.  Unfortunately, Nantucket’s moderate climate doesn’t usually make for excellent displays of autumn leaves.  Most years, we go from a lush green nursery in September to rows and rows of bare twigs by mid November without much fall color in between.  I couldn’t help but notice a stunning show of yellow from a group of sweetpepperbush (aka summersweet) in the shrub area today, however.  On a dingy autumn afternoon, they really brighten things up.

Clethra alnifolia, as botanists refer to it, is a native North American plant that is endemic to Nantucket where it can be found growing in low-lying areas and at the edges of wetlands.  If grown in moist soil, it tends to sucker and form colonies over time.  However, this plant is well-behaved and very adaptable, doing well in most any island garden where average soil and even water is available.  It prefers full sun, but will flower in shade.   The overall look of these plants is a pleasant green, twiggy shrub with an upright, balloon-shaped habit.  They have medium green, rounded, ovate leaves with finely-toothed edges.  In mid summer, they produce loads of fragrant flowers that are reminiscent of small, skinny bottle brushes.  The native form of this plant generally has white flowers, but there are pink cultivars available, as well.  Beneficial insects like it just as much as we do; many species of butterflies, bees, wasps, flies and other flying insects frequent the plant while it is in flower during July and August.

Clethra can serve many uses in the landscape.  If planted in a row, they make a great informal hedge that doesn’t require much pruning to maintain a tight shape.  I’ve seen them used very well in mixed shrub borders with both native and ornamental plants.  They make natural companions to bayberry, arrowwood, groundsel and beach plum, but look just as well among ornamental plants like butterfly bushes, vitex, shrub roses and spiraea. They respond very well to pruning and can be maintained at a height of five feet or so with an annual pruning.  Some gardeners prefer to remove the spent flowers while others leave them on the plant to be covered up by the new growth in spring.

There are many cultivars available in the trade as well as the straight species:

Clethra alnifolia:  The species form of this shrub.  Generally grows 3-4′ wide and 6 or more feet tall.  White flowers.

‘Anne’s Bouquet’:  White flowers.  Average size.

‘Hummingbird’:  Compact, white-flowered form.  2-4′ wide and up to 5′ high.

‘Pink Spires’:  Pink-flowered form, average size.

‘Ruby Spice’:  Pink flowers, average size.

‘Rosea’:  Pink flowers.  Average size.

‘Sixteen Candles’:  Compact, white-flowered selection with white flowers.

‘Vanilla Spice’:  Proven Winners introduction.  White flowers, touted to be larger than most.  Average size.

During the season, Surfing Hydrangea is a very busy place!  In order to keep the nursery full, we are constantly bringing in the staple trees and shrubs that landscapers are using day in and day out.  But luckily,  Craig is a plant geek at heart, just like me, so he also stocks a wide variety of lesser-known plants.  Over the last few years, we’ve been delighted to see a dramatic uptick in sales of our native arrowwood viburnum (Viburnum dentatum).  Arrowwood is a great shrub that can be used in a variety of applications, like medium-sized hedges and naturalized screening on property lines.  If you like the look of arrowwood, but want to try something a little different with showier fruit, check out linden viburnum (Viburnum dilatatum).  

This East Asian native has white lace-cap flowers and showy fruit in the fall.  The rounded/oval, toothed leaves are generally lustrous deep green with a quilted look.  Like many viburnums, Viburnum dilatatum grows well in evenly moist soils with average organic matter.  Plants thrive in full sun or part shade.  We have offered several cultivars over the years, some with red fruit, and some yellow.  Although this plant is self-fruitful, much of the literature mentions fruit set is improved with multiple varieties planted in close proximity.

• ‘Asian Beauty’ has vigorous upright habit (10′) with deep green, thick, shiny leaves during the growing season.  This variety has cherry red fruit.  Fall foliage is maroon.
• Cardinal Candy tm aka ‘Henneke’ is a Proven Winners introduction.  This selection is listed as 5-6′ tall.  The large, bright red fruit contrast very well with the dark green leaves, and persist long after the leaves fall in autumn.  Cardinal Candy is purported to have a heavy fruit set without additional varieties planted for cross pollination.  Foliage is reddish orange in fall.
• ‘Michael Dodge’ is a stand out among viburnum, with bright yellow fruit.  This plant is said to grow 5-6′ tall.  Best fruit set is observed when planted with other varieties for cross pollination.  Fall color is reddish/orange.  Choose this variety over ‘Xanthocarpum’, an inferior yellow-fruiting variety, according to Dr. Michael Dirr.
• Tandoori Orange is the first orange-fruited variety of linden viburnum.  This Proven Winners selection is similar to Cardinal Candy tm, and a good pollinator for other linden viburnum selections.

We have some stocky field grown ‘Michael Dodge’ and ‘Asian Beauty’ on the ground as well as some nice container grown Cardinal Candy tm.  We’d be happy to show them to you.

Inkberry, Ilex glabra, is a beautiful, rounded, evergreen shrub that grow 5 – 8′ tall.  It prefers full sun and evenly moist acidic soil, but does well in wet areas and light shade.  When properly pruned, inkberry can make a nice foundation plant or short hedge, but is best used in native screens and rain gardens, where it can be left to grow naturally with little intervention needed from the gardener.  Young plants are perfectly round, with leaves right to the ground.  As plants mature, however, the canopy tends to shade out the bottom portion of the plant and their lower branches can become bare and leggy.  Regular pruning is required to keep inkberry looking its’ best.

Most applications for inkberry call for a plant that is maintained at 3-4 feet.  Once they reach this size, they need to be pruned at least once a year to keep in bounds.  Shearing with hedge trimmers (when new growth has just hardened off in early summer) is the easiest way to prune rounded shrubs.  Although this approach takes the least amount of time, repeated cycles of shearing can make the surface of the plant very dense, shading out the lower branches.  I recommend doing a more thorough pruning procedure every other year to open up the plant.  More light penetration stimulates new growth at the base and keeps the plant healthier overall.  Should plants become overgrown and overly leggy, a renovation can be done during the dormant period in winter or early spring.  I’ve actually cut overgrown inkberry to the ground while dormant and had excellent results.

There are several objectives when doing regular pruning on inkberry:

• To remove dead or damaged branches
• To maintain the proper height and shape
• To keep the plant green from the ground up, (not leggy)

Understanding the growth pattern of these plants helps the gardener when making pruning decisions.  Growth in the upper portion of inkberry plants occurs in whorls.  A whorl is a ring of new stems that grow around a central, upright stem. There are many dormant buds between whorls on bare portions of the stems, even on the oldest woody stems.

On off years, when plants are not sheared, follow these guidelines:

1. Remove any dead or dying branches completely, where they meet healthy growth.
2. Pinch out most of the previous seasons’ growth just above a whorl to thin out the surface and keep the plant at the best height.
3. Most cuts are made in the previous season’s growth, but several cuts can also be made into older wood, to stimulate growth lower down.
4. As plants age, some of the oldest branches can be removed entirely at ground level in favor of younger, more vigorous growth.

There are several varieties of Inkberry available in the trade.  The most common are ‘Compacta’ ‘Densa’ and ‘Shamrock’.  Of the three, ‘Shamrock’ is the most highly praised by Dr. Michael Dirr in his extensive text book Manual of Woody Landscape Plants.