Category Archives: Trees and Shrubs

woody plants, trees and shrubs

Indigofera amblyantha

Indigofera amblyanthaIt’s time to love pink, and how can anyone say no to a flowering shrub that produces upright racemes of soft pink pea blossoms from late spring right through fall. Indigofera amblyantha, commonly known as Chinese Indigo, is a member of the legume family, so it fixes its own nitrogen from the soil and thus is a candidate for poor soil conditions. It asks for full sun and good drainage, and is hardy in zones 6-9. It wants to be a multi branched shrub but we have seen it charmingly pruned to a single leader (to appear as a small tree). In zones with severe winters, Indigofera amblyantha may get winter die back, so we suggest that if you try this pruning treatment, do so on plants located in a sheltered spot and consider it as an experiment. Then again, should die back occur, you can always enjoy this plant as the bushier shrub it is more inclined to be.

Attractive companion plants for Indigofera amblyantha are Calamintha nepetoides, Euphorbia ‘Blue Haze’ and Sedum ‘Maestro’.

Ilex verticillata

December is the perfect month to enjoy this eyecatching deciduous holly whose brilliant berries, clustered on bare branches, provide splashes of color to the early winter landscape. Commonly called Winterberry, this North American native is found in the wild from Nova Scotia to Florida, usually growing in low lying areas, since it doesn?t mind wet feet. It is nonetheless adaptable to many soil types and will be happy enough in dryer locations. A large number of clones have been selected for their eventual stature, as well as for variation in fruit color and size.

As you probably know, the genus Ilex is dioecious, meaning there are different male and female flowering plants, and they have to tango for fruit set. Take note that there are earlier and later flowering selections of Ilex verticillata and it is a good idea to plant a male counterpart that blooms at the same time as the female clone.  Some of the earlier blooming female clones such as ‘Red Sprite’, ‘Berry Heavy’ and ‘Berry Nice’ should be pollinated with the male clone ‘Jim Dandy’. Use ‘Southern Gentleman?’, a late-blooming male pollinator for ‘Winter Red’, ‘Winter Gold’, ‘Capacon’, ‘Sparkleberry’ and the other later blooming girls.

Ilex verticillata waits until fall to become a star when the berries begin to color, so it is best sited in a spot where it does not have to be commanding all season long. Remember Winterberry does sucker, but this can be useful where you want to create a screen to attract wildlife. A number of years ago, we used it in repetition behind one of our beds that borders a wet area, and the planting now provides us with a bounty of branches for cutting.  Eventual plant size is dependent on which cultivars you select, and they range from 3-4′ to 12′ or more. Plants enjoy sunny or partially shaded exposures, soil that is acid to neutral, and are hardy through zone 4.

Cornus sanguinea ‘Arctic Sun’

Cornus s. 'Arctic Sun'You won’t pay much attention to Blood Twig Dogwood in spring and summer. The ordinary green foliage is attractive enough, but it does not sing “Here I am!”. It’s not until autumn, when Cornus sanguinea ‘Arctic Sun’ starts to make music in clear apricot tones with the changing fall foliage. Colder temperatures transform its green branches into stalks of vibrant yellow, orange and red which glow in an otherwise increasingly dull landscape.

‘Arctic Sun’ (a.k.a. Cornus sanguinea ‘Cato’) is a compact clone of Blood Twig Dogwood, reaching only 4-5′ tall as opposed to 8-10′, and this size is useful in smaller gardens. It thrives in average to moist soil in full sun or part shade, is deer resistant, and is hardy in zones 4-7, which means it will take temperatures to minus 30F, but probably won?t be happy in mild winter climates. We recommend planting ‘Arctic Sun’ in a location so that the dazzling winter stems can be viewed from an inside perch, perhaps where you sit with your morning coffee, or where you might pass by as you enter and leave your home. You’ll enjoy the show all winter, and may even be inspired to cut a few branches for decoration.

One thing you should note is that the best color on twig dogwoods is displayed on young wood. Every two or three years you should “stool” yours plants in early-mid spring. Stooling is a simple pruning technique where you cut back the entire shrub to about 6′ above ground. The new growth will provide a more colorful display when late fall and winter arrives.

Hydrangea paniculata ‘Quickfire’

Hydrangea paniculata 'Quickfire'We were walking through the nursery with a couple of friends, observing which plants displayed the most exciting autumn color, when this Hydrangea stopped us in our tracks. The fall foliage on the panicle Hydrangea, Quickfire’, was spectacular! Its chunky lacecap type blossoms were fading to a lovely shade of mauve rose, but it was the warm red to amber coloring of the leaves that stopped us in our tracks. Interestingly, blocks of Hydrangea paniculata ‘Limelight’were grouped nearby, and their foliage was just an ordinary shade of green. We checked online, but the literature on ‘Quickfire’ didn’t glorify its fall color. Hmm…was this due to the weather this season, or perhaps our magic touch? Upon further investigation we learned that indeed this selection was an autumn star.

Quickfire’blooms on new wood, so there is little danger that you will be without blossoms after a severe winter. The large panicles (to 12′) of white sterile and fertile flowers form early in the season, and will develop rosy red tones as they age. The stems have a dark red tint, which further accentuates the blossoms. Plants grow 6-8′ tall and 8-10′ wide.  Pruning can be done in late winter or early spring.  ‘Quickfire’ prefers full sun or partial shade and is not fussy about soil or moisture, although plants will be happier if irrigated during dry spells.  Hardy in zones 3-9.

Acer palmatum ‘Katsura’

Acer palmata 'Katsura'In the fall, we turn our attention to trees, and this cultivar of Japanese Maple demands the spotlight in our front garden. It shows off earlier in the year, as well, in mid spring, when Acer palmatum ‘Katsura’ begins to leaf out in lovely apricot yellow tones. The new foliage holds that color until warm weather settles in, and gradually becomes a yellow green for much of the summer. In mid October, the leaves will begin to transform from a happy green to blazing tones of yellow, orange and red. The fiery foliage lingers through early November, after which the handsome silhouette of ‘Katsura’ provides structural form in the winter landscape.

Acer palmatum ‘Katsura’ has a dense growth habit that should be pruned to a shape that suits your garden. It reaches a height of 10′ at 10-15 years of age, and can ultimately attain 20′ uncommon or more. It loves humus rich, well drained soil, and will do well in a spot that gets morning sun, afternoon shade. It is hardy in zones 6-8, and possibly in zone 5 in a protected location

Euonymus sachalinensis

Mention the genus Euonymus and immediately people respond with ugh! Burning Bush! It’s invasive! It’s banned from commerce! All valid responses if you’re talking about Euonymus alatus, but we want to cue you in on a different, lovely and until now, uncelebrated Euonymus, commonly known as Asian Spindle Tree.

We first discovered this plant on a September morning two decades ago, when the Arnold Arboretum held their annual plant sale at the Case Estates in nearby Weston MA.  Along the path to the barn there was a planting of Euonymus sachalinensis (a.k.a. Euonymus planipes) espaliered along a fence, where the horizontal branches were dripping with the showiest seed pods. The pinkish red seed capsules had burst, displaying dangling red orange fruit. There were no specimens for sale, but we found a source for seed a few years later, and after incubating for 2-3 years in a seed pan, signs of life finally occurred.

This is what you need to know. Asian Spindle tree is native to Sakhalin Island off the northern coast of Japan. It is slow growing as a youngster, but eventually forms a small tree to 15′ with a wide crown. It can be pruned to great effect, as the espaliered version which we so admired at the Case Estates proved. It does flower, or how else would there be fruit, but the blossoms are not the real show. Fall is the season to celebrate Asian Spindle. Colorful September fruit, crimson pink fall foliage. It is amazingly adaptable to soil types, except perhaps very wet ones, and grows best in full sun or part shade. Most often it is listed as hardy through zone 6, but we’ve heard reports from growers who have had success with it in zone 5. Find a spot in your fall garden for this gem.

Clethra barbinervis

Japanese Clethra is waiting to be discovered.  It is a plant for all seasons, boasting fragrant mid summer blossoms, yellow-orange to red fall foliage, and exfoliating bark in winter. If left unpruned it will grow as a multistemmed shrub or small tree, but we prefer to see it trained to a single leader, with lower limbs removed, so that the showy bark can be better appreciated.

We were smitten when our young plant came into bloom in July. Trios of sweetly scented white, 4-6″, twisting racemes will drip from the branches into August. The ovate serrated foliage, in a shade of dark green, really sets off the white blossoms. Fall color is also striking, ranging form yellow orange to deep red. Although Clethra barbinervis is fast growing, it seems to reach an ultimate height of 15-20′. It prefers a well drained, neutral or slightly acidic soil with adequate moisture. Clethra barbinervis grows well in partial shade, although it will tolerate and bloom abundantly in full sun, if watering needs are met. It can be cultivated in zones 5-8.

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Hydrangea arborescens ‘Hayes Starburst’

Hayes Starburst Hydrangea is a floral arranger’s dream. This chance discovery, by Hayes Jackson of Anniston, Alabama, differs from the species by its showy display of clustered greenish white, multi sepaled star shaped flowers. It is a form of Hydrangea arborescens, also known as Smooth Hydrangea or Hills of Snow, and although native to the southeastern U.S., is cold hardy into zone 4.

Hydrangea arborescens ‘Hayes Starburst’ blooms on new wood, so there is little danger of winter damage to flower buds. We recommend cutting back the woody stems to 12″ in early spring to keep the plants tidy. Hydrangea arborescens prefers to grow in full to half day sun and in a well drained soil that still gets adequate moisture. If there is a common complaint about this species it would be that the flower clusters are so heavy that they weigh down the supporting stems. Some consider this an addition to the plant’s charm, and if it is sited on a slope or above a retaining wall, you could take advantage of its cascading habit. If an upright habit is preferred, situate a large tomato cage over the cut back stalks in spring, which will lend support. The height and spread of this shrub can remain a manageable 3′  x 3′, if pruned annually.

Sorbaria sorbifolia ‘Sem’

First, we fell in love with the foliage. The new foliar growth is a delicious shade of caramel pink, gradually becoming lime green as the summer progresses. As the July heat intensifies, 4-6″ panicles of white pearly buds burst into creamy Astilbe like plumes. Sorbaria sorbifolia ‘Sem’ is a compact growing False Spirea, growing only to 48″, unlike the species which can reach 8′ or more.  ‘Sem’ will give you moderate height without obscuring your view. Yes this form will sucker and form a thicket…but that is why you should use this shrub as a low hedge, or for filling a space that you don’t want to fuss over.

Here are the other pertinent facts: Sorbaria ‘Sem’ grows in full sun or part shade, is deer resistant and is hardy to minus 35 degrees F. Pretty and tough, don’t you think?

Rhododendron ‘New Century’

‘New Century’ is another tidy compact Rhododendron, with pale citron yellow blossoms. It has a very full foliage appearance due to the fact it holds its evergreen leaves for 3 years, rather than just 2 like most other rhodies. It grows to a well behaved 4′ x 4′ size and is quite hardy for a yellow form, (to minus 15F).

Grow this selection in a spot protected from drying winter winds. Morning suns and afternoon shade is ideal, but plants can take more sun if well irrigated during drier conditions. Like all Rhododendrons, ‘New Century’ appreciates a humus rich soil that remains moist but well drained.