September in Kew Gardens

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Thanks to my daughter's decision to spend a Semester Abroad in London, I was able to visit several wonderful English gardens in September. The first was the Royal Botanic Gardens in Kew - regarded as the world's number one botanical garden with the largest and most comprehensive plant collection. What began as a "physic garden" of 9 acres in 1759 is now a 300 acre property with an arboretum, woodland, rock garden, Holly Walk, Winter Garden, numerous perennial beds and formal display gardens.

In addition to the plants, the garden is home to beautiful conservatories, museums, palm houses, Kew Palace and several temples. Since we had only one afternoon to spend there, we focused on the horticulture. Below are some views of the fabulous garden in September.

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Kew's arboretum is a living library of trees that stretches over the majority of the Gardens and is a wonderful place to see many different species of trees including rare and ancient varieties.

 This specimen monkey puzzle tree was planted in 1978. The first monkey puzzle trees were brought to the UK in 1795 from chile.

This specimen monkey puzzle tree was planted in 1978. The first monkey puzzle trees were brought to the UK in 1795 from chile.

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There are more than 2,000 species of trees in the vast arboretum including a collection of "Old Lions". These magnificent trees are the oldest trees with known dates in the Gardens, dating back to 1762.

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Grasses and perovskia sway in the breeze and create a soft foreground for the collection of trees and shrubs.

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The Duke's Garden showcases perennials with beautiful foliage such as the bergenia and heuchera above.

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The large rock garden displays a range of mountain plants, Mediterranean plants, and moisture-loving species from around the world.

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The beautiful Japanese Garden is comprised of three areas. Above we see the Garden of Peace, reminiscent of a traditional Japanese Tea Garden with stone lanterns and a dripping water basin.

Below, is a glimpse of the Garden of Activity, symbolizing the elements of the natural world such as waterfalls, mountains and the sea. The raked gravel and large rocks represent the motion of water as it swirls and tumbles.

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Gardening in the Hellstrip

The hellstrip — the space between a street and a public sidewalk, also known as a tree park, boulevard, meridian, and planting strip — is getting a lot of attention these days with the publication of Evelyn Hadden’s Hellstrip Gardening by Timber Press. This comprehensive guide with gorgeous color photographs of hellstrip gardens across the country offers inspiration and visual guidance to anyone ready to tackle this final frontier.

Hellstrip gardening is nothing new to my friend Kathy, who has been adding curb appeal to her home with hellstrip plantings for 15 years. Kathy began her roadside garden when she got tired of trying to keep the lawn grass alive in the hellstrip year after year. Always keen on water conservation, Kathy wanted a low maintenance solution for this long, sunny expanse. Her large backyard garden had also become shaded over the years as the pine trees grew taller and taller, so the sunny hellstrip offered a chance to relocate her sun lovers from the backyard and to try some new plants in this totally different environment.

She began the garden by digging up a small section of sod around her mailbox, amending the soil, and planting various sedums that would be low maintenance and drought resistant. Bit by bit, the hellstrip garden grew, and then expanded to the other side of the driveway. Now it measures close to 100 feet, and boasts a wide variety of perennials. Kathy learned through trial and error which plants to grow, and which plants to avoid. Some perennials, like yarrows, were too tall and floppy. Annuals were too labor intensive, except for the portulaca that self sows and returns year after year. But there were many perennials that acclimated to this dry, sunny area with its relatively poor soil.

Mediterranean plants and herbs – many of which sport silver foliage and prefer a sunny situation with lean soil and good drainage, thrive in Kathy’s roadside garden. Sedums, Lamb’s ears, salvia, sage, alliums, fescues, rosemary, thyme, mint, sea lavender, and catmint bask in the baking hot sun. The garden delights passersby with a changing palette of blooms and foliage. In the early spring, crocus, creeping phlox and species tulips, which love the good drainage, cheer up the border with their blooms. They are followed by stately bearded irises, columbines and poppies in June, and daylilies, helianthus and coreopsis in mid summer. A prickly pear cactus at the base of the mailbox surprises visitors with its yellow flowers in July. Sedums steal the show in August. In a shadier part of the garden, hostas and heucheras provided beautiful foliage from spring to fall.

Gardening in the hellstrip has its challenges. The soil in these areas is usually cheap, compacted fill. Kathy amends it at planting time with compost, and has been top dressing with leaf mulch. Because of the distance from the house, the garden is difficult to water. Although Kathy does not irrigate regularly, newly installed plants need supplemental watering, which amounts to many trips with a watering can. Weeds easily blow into the garden and crabgrass is a particular problem. Since the hellstrip is town-owned property, large sections have been dug up utility companies several times without prior notice.

But overall, gardening in the hellstrip has been a positive experience for Kathy. Neighbors stop by to admire the garden, and Kathy receives many compliments on sprucing up the neighborhood. “The hellstrip builds community,” says Kathy. “People stop by to chat and ask about the flowers. And it gives me a chance to try plants that I couldn’t grow anywhere else in my garden.”

Davidia Tree – Worth the Wait?

When I first read about Davidia trees, I was immediately fascinated. Imagine finding something that satisfied both my love of flowering trees and my love of unusual plants! It seemed the perfect choice for the long shade border I was creating across my backyard.

So, when I found a Davidia involucrata at an end-of-season sale at Weston Nurseries, I immediately bought it. It was small, only about five feet tall, but I had high hopes. I planted it, nurtured it and awaited the grand show.

After five years had passed with not a flower in sight, I did some homework. I found that not only was it border-line hardy in my area, but it typically did not bloom for twelve years after planting. It was a good grower and created nice shade; its leaves were attractive and it had lovely bark; I consoled myself as I waited for Year Twelve.

Year Twelve came and went. Finally, after thirteen years, I was thrilled when one branch produced some of the most intriguing flowers I had ever seen: fuzzy brown spheres with two white bracts, the larger one nearly seven inches long! This continued for the next couple of years: a branch here and there with a smattering of flowers. But this year, nearly the entire tree is blooming. As the white bracts of each flower flutter in the breeze, I can see why its common names are Handkerchief Tree and Dove-tree. It is just as fascinating as I had imagined.

And, yes, it was worth the wait.

By Joan Butler


Variegated Kousa Dogwood: The “Eyes” Have It

Plants with variegated foliage add interest and vitality to the home landscape. They brighten shady corners and create a feeling of depth and movement in the shrub border. In addition, they make a noticeable contribution throughout the entire growing season: colored leaves are longer lasting than the longest blooming flower.

Variegated plants help bring attention to plain green plants in their midst, by virtue of contrast. Large variegated plants should be selected judiciously. One or two contribute just the right amount of drama and clarification to the shrub border, too many overwhelm.

Variegation can take many forms. On some plants, green leaves are splashed or streaked with color, such as yellow, white and pink. On other plants, leaves may be edged with contrasting color. This can mean a green leaf outlined in white, or a white-centered leaf outlined in green. There are many variations on this theme, with purple, yellow and pink combining dramatically with shades of green to produce plants of stunning beauty.

One such plant is a variegated form of the popular kousa dogwood, Cornus kousa ‘Wolf Eyes’. This tough, shrubby tree reaches a height of 10-15 feet at maturity and is nearly as wide as it is tall. It is an excellent small specimen tree and is a valuable addition to the shrub border. It flowers in late spring, after our native dogwood. Each bloom is made up of four white, pointy bracts that can last up to 6 weeks. These are followed by red, raspberry-like fruits that are produced in late summer.

Like other kousa dogwoods, ‘Wolf Eyes’ prefers fertile, acidic soil that is neither very wet nor very dry. It is considered disease-free and has few pests. Mature trees have mottled, attractive bark that adds to its beauty and provides winter interest.

It is the show-stopping foliage of the ‘Wolf Eyes’ kousa that sets it apart. Each 3-inch-long, grey-green leaf is margined with white. This contrasting leaf edging emphasizes the leaf shape: elliptical with wavy, rippled edges. New summer growth is flushed with pink, as are the new branches. Fall brings these pink tones to every leaf, for a distinctive autumn show.

I have planted a ‘Wolf Eyes’ kousa in my shrub border, where it simultaneously  is accented by and calls attention to adjacent all-green shrubs such as longstalk hollies and rhododendrons. It is a harmonious companion to hostas that echo its white-edged leaf variegation, such as H.’Cherub’ and H.‘Tambourine’. It is complemented by other green-and-white variegated perennials that have distinctly different forms: a dwarf striped grass and a stand of Solomon’s Seal.

Grouping different variegated plants can sometimes produce garden chaos, but this collection has a sense of serenity and harmony. This is achieved by casting the ‘Wolf Eyes’ kousa in the leading role and pairing it with plants that either have related variegation or no variegation.

Even within a named cultivar, such as ‘Wolf Eyes’, variegation can vary from plant to plant. When I was selecting my tree, I had six specimens to choose from at the nursery. The variegation was slightly different on each one, so leaf pattern was an important consideration for me, as was tree health and branch structure. Ultimately, I chose one that had extremely wavy leaves and green flecks in the white margin. This tree never fails to elicit comments and questions from guests, who find it just as fascinating and gorgeous as I do.

‘Wolf Eyes’ kousa dogwood is as eye-catching as its name suggests. Its stunning variegated foliage, white flowers and mottled bark add drama, beauty and distinction to the home garden and landscape.

By Joan Butler

Redvein Enkianthus: Easier to Grow Than to Say

Recently, I came across a list of Cary Award-winning plants. The Cary Award program is designed to promote the use of outstanding plants for New England gardens. It is administered by Tower Hill Botanic Garden in Boylston, MA and is named after Shrewsbury plantsman Ed Cary. One of the purposes of the program is to highlight relatively uncommon plants that New England gardeners can choose with confidence as good performers for their home landscapes. In its first year, 1997, five plants were selected as winners, including one of my favorites, the Redvein Enkianthus.

I first encountered this plant many years ago, while visiting a lovely garden full of towering rhododendrons, mountain laurels, and azaleas in Concord, MA. As I walked along the woodland paths, I glanced up and saw I was beneath a tall, smooth-barked shrub with dangling, bell-shaped creamy pink flowers. Later, I asked the owner about the plant and learned it was a Redvein Enkianthus.

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Redvein Enkianthus (Enkianthus campanulatus) is an upright deciduous shrub that is native to the open woodlands of Japan. It has a slow to moderate growth rate, but can eventually reach the size of a small tree (15 feet). It is hardy in Zones 4-7, making it an ideal selection for New England gardens. It has a graceful, layered branch pattern, with leaves clustered at the branch tips. The leaves are elliptical, 2 -3” long with lightly serrated edges. The green to bluish-green summer foliage turns to show-stopping shades of brilliant red, orange and yellow in fall. When grown from seed, the color of autumn foliage can vary from plant to plant. This leads some gardeners to purchase Enkianthus in fall or to select cultivars that are vegetatively propagated and known for fall color.

The flowers are unusual, with a delicate appearance that is best appreciated when viewed up close. Bloom time is late spring/early summer; each flower is one-third to one-half inch long. The flowers hang in clusters near the branch tips and are creamy white accented with red veins. They are followed by dangling, brownish-yellow seed capsules, that add an element of beauty to the winter landscape when frosted with a light coating of snow.

Hybridizers have introduced new cultivars with an increased range of flower color, including ‘Renoir’, which has yellow flowers with pink lobes, and the white flowered ‘Albiflorus’. Flowers may also be pink to red, such as the dark-pink flowered ‘Showy Lantern’, selected by the late Ed Mezzit of Weston Nurseries, and the red-flowered ‘Red Bells’.

The Redvein Enkianthus prefers cultural conditions similar to those required by rhododendrons: acidic soil, with good drainage and moderate moisture. It is useful in the woodland garden, in the shrub border or as a specimen plant. It prefers part shade to full sun. It is considered pest- and disease-free, and is rarely severely damaged by deer.

My own Enkianthus is now nearly ten feet tall and has been pruned to function as a small, multi-trunked tree in my landscape. It is planted next to my deck, where we can enjoy its dainty spring-time flowers at eye-level. Right now, in early March, its pointy little buds are yellow at the base and rosy pink at the tips, and give the sense that spring is just around the corner. In summer, it receives about six hours of midday sun, and is underplanted with daylilies, Hosta ‘Sun Power’ , Heuchera ‘Mint Frost’, Carex ‘Evergold’, and a smattering of self-sowing, white-flowered Nicotiana.

The Redvein Enkianthus is easily grown and deserves to be more widely used in the home landscape. It is a valued addition to the woodland garden and is also ideal for small gardens, due to its slow growth rate. It offers four-season interest with its delicate spring flowers, rich green summer foliage, brilliant autumn color, and the winter prominence of its seed capsules and smooth gray-brown bark. I wouldn’t be without this graceful, distinctive shrub.

By Joan Butler

The Longstalk Holly: To Grow It Is to Love It

Plant explorers of the 19th and 20th centuries introduced hundreds of eastern Asian plant species into western cultivation. Many of these plants have become so common in the American landscape, that it is difficult to imagine our gardens without them. Forsythia, weeping cherry trees, Japanese maples, Sargent crabapple and old-fashioned bleeding heart are just of few of the Asian introductions we rely on to create beauty in our gardens. The Star Magnolia, double-file viburnum, and Korean lilac are also valued contributors to North American gardens.

Other introductions are less common, and sometimes inexplicably so. One of these is Ilex pedunculosa, the longstalk holly. Native to China and Japan, this evergreen holly is a large shrub or small tree with a sturdy constitution and graceful beauty. It has a dense, upright branching habit when young that becomes more open with maturity. Plants in the wild reach heights of 30 feet, but 15 feet is typical in garden settings. It responds well to light pruning, making it adaptable to the shrub border.

The smooth, green leaves of longstalk holly are 2-3 inches long and 1 ½ inches wide. They are non-spiny, with a satiny sheen and gently rippled edges that catch the light, adding to the shrub’s distinction. Its most unique feature is the bright red berries that hang from one- to two-inch long slender stalks (pedicles), resembling tiny cherries. These fruits are one-quarter inch in diameter and appear in early fall. They persist on the plant well into winter, until they are eaten by birds and other wildlife. As is common in hollies, both male and female plants are needed in order for the female to set fruit.

Longstalk holly was first grown in North America from seeds planted at the Arnold Arboretum in 1907, under the direction of Charles Sprague Sargent, a plant explorer and the first director of the Arboretum. It has proven to be long-lived and extremely cold tolerant, with some of the original specimens still gracing the Arboretum landscape. It is dependably hardy through Zone 5 and has been documented as surviving temperatures as low as -18 degrees with no damage. Like all hollies, it prefers a well-drained, slightly acidic soil. It thrives in partial shade and has no serious pest or disease problems.

My own longstalk hollies were planted over 15 years ago. They were slow-growing at first, then hit their stride and are now 10-foot tall beauties that add grace and diversity to my shrub border. Their long branches are very supple, and it is amusing to watch squirrels as they try to inch their way along the swaying branches to nibble on the tasty fruits. Towards the end of winter, the only berries left uneaten are at the branch tips, and I have seen birds attempting to jump/fly up to grab a berry on their way down. How glad I am that I planted my longstalk hollies across from my kitchen window, where I can appreciate their year-long beauty and enjoy watching wildlife feasting on their fruits.

Longstalk holly is surprisingly under-used in the home landscape. Its lustrous, wavy leaves add depth and motion to the garden as they catch the light of the sun. Its shiny red, dangling berries add unique beauty and provide food for birds and its graceful form adds elegance to the shrub border. In his book, Manual of Woody Landscape Plants, Michael Dirr calls it “the most handsome of the evergreen hollies that can be grown in northern gardens”. Easily grown, disease-free, and beautiful in all seasons, longstalk holly deserves a place in every home garden.

By Joan Butler

Witch Hazel Cures Spring Fever

At this time of year, when I am yearning for any sign of spring, I get the boost I need from the winter blooms of witch hazel. Their ribbon-like flowers in shades of yellows, oranges and reds fill the winter air with a clean, sweet scent that is most welcome to this winter-weary New Englander.

Witch hazel (Hamemelis) grows as a large shrub or a multi-trunked small tree, with deeply ribbed green summer foliage and an open shape that requires little pruning. Its unique flowers resemble shreds of crepe paper, with four dainty, twisted petals radiating out from the center. Individual petals are thin and can be up to three-quarter inch long; flowers are typically one-half to two inches in diameter and can last for several weeks. Witch hazel has an architectural branch structure and glorious fall foliage colors. But, its most outstanding attributes are its wonderful fragrance and its unusual bloom time: from mid-fall to late winter, a time when most plants in temperate gardens are in a state of dormancy.

Vernal witch hazel (H. vernalis) and autumn witch hazel (H. virginiana) are native to North America. Vernal witch hazel, hardy to Zone 3, is a spreading, suckering shrub that reaches heights of around ten feet. It flowers the earliest of all the winter-flowering types. Bloom time is in January-February/March, a time when little else is going on in the garden. Its fragrant flowers have red-tinged yellow petals that curl up on very cold days to avoid freeze damage; in this way, blossoms can last 3-4 weeks. Flowers are small, but plentiful. Fall leaf color is an outstanding yellow that can often persist for 2-3 weeks.

Autumn witch hazel, hardy to Zone 4, is a common understory tree/shrub in the eastern US. Witch hazel extract is made from the bark of its young stems and roots. It can reach heights of 30 feet with a spread of over 15 feet. (For smaller gardens, H.'Little Suzie' grows to a height of 5-6 feet.)  Autumn witch hazel has large, yellow flowers with four crumpled and crimped petals. It blooms in late October-November, a time when most deciduous shrubs already have had their last hurrah. Its fall leaf color is a brilliant yellow and occurs concurrently with the yellow flowers to create a beacon of gold in the landscape. Its sweet scent spreads a great distance in the crisp autumn air.

The Asian species of witch hazel (H. japonica from Japan and H. mollis from China) have been crossed by hybridizers to create spectacular cultivars, termed H. x intermedia. All bloom in late winter/early spring, after the vernal witch hazel. These vase-shaped shrubs are hardy to Zone 5, grow 15-20 feet high, and have a wide range of flower color and autumn leaf color. H.'Arnold Promise' is a cultivar introduced by the Arnold Arboretum. It has large, fragrant yellow flowers, each petal nearly an inch long, and a bloom time that is among the latest of all witch hazels. H. 'Diane' is considered the reddest of the red-flowering types. 

H.'Jelena' offers flowers with inch-long petals that are red at the base, orange in the middle and yellow at the tips. The overall effect from a distance is of glowing copper.  Fall leaf color is rich orange-red. The number of H. x intermedia cultivars is staggering – your main problem will be in settling on which one to choose!

Witch hazel is easy to grow. It does well in most garden situations, but grows best in conditions that are similar to its native woodland habitat: slightly acidic organic soil that is well-drained but not overly dry, and morning sun or dappled sunshine. It will also do well in full sun in the northern reaches of its range.  In the home garden, witch hazel can be planted as a specimen or as part of a shrub border. It should be sited to take advantage of its unique features: its brilliant autumn leaf color, which ranges from bright yellow to orange to red, its curled and crimped blossoms,which are stunning when backlit by the soft light of the winter sun, and its fragrance, which perfumes the cold air of a mid-fall or late winter day.

Numerous witch hazel cultivars are currently in bloom at Tower Hill Botanic Garden in Boylston, MA. You can purchase your own witch hazel at many local nurseries and through mail-order sources such as RareFind Nursery (www.rarefindnursery.com).

By Joan Butler

Japanese Stewartia: A Multi-Season Beauty

asily grown and beautiful in all four seasons, Japanese Stewartia earns its keep in the garden year-round. Valuable as a specimen tree in the lawn or shrub border, it offers long-term impact in the landscape with its summer flowers, brilliant autumn color and exfoliating bark that provides dramatic winter interest.

Japanese Stewartia (Stewartia pseudocamellia) is perfectly suited to the suburban landscape. In the winter, its beautiful bark and sinewy, muscular trunk and branches create an unbeatable effect. The bark has the look of camouflage gear, smooth with patches of rich gray, tan and terra cotta.

The tree has a pyramidal shape, and young branches have a slight zig-zag pattern of growth with small pointy buds at their tips. Its architectural beauty is especially dramatic when the tree is outlined with a fine tracery of snow. Japanese Stewartia is one of the few trees that bloom in the summer, producing a succession of camellia-like white flowers with gold anthers for more than two weeks in July. In the fall, it dazzles! Its lustrous green summer foliage turns to shades of yellow, red and reddish-purple. When back-lit by the sun, it is breathtaking.

A bit of advice about Japanese Stewartia: be sure to plant it where you can see it all year long – you won't want to miss a thing! Mine is planted across the yard from my kitchen window so I can enjoy it easily in every season. The tree is now large enough to fill the view from the window. In the summer, it adds to the serene beauty of my shrub border. It is underplanted with shade-loving, long-lived perennials: golden Japanese forest grass (Hakonechloa macra 'Aureola'), Hosta (H. 'Liberty', H. 'Kabitan', H. 'Kiwi Blue Baby'), shiny European Ginger (Asarum europaeum) and assorted Epimedium cultivars. Add some coleus and angel-wing begonia and you have a heart-stopping moment in the garden. In the fall, the Stewartia's blazing foliage takes center stage. And in the winter, its patchwork bark pattern stands out against the snow and clear blue sky. This naturally well-shaped tree is one of the most desirable small- to medium-sized specimen trees around.

How can a tree that offers so much require so little? Plant Stewartia in well-drained humus rich soil in a sunny spot with some afternoon shade and you will be rewarded with years of stunning beauty. It reaches 30-40 feet at maturity and has no major disease or pest problems. It is somewhat pricey, but the distinct contribution it provides to the four-season landscape makes it a garden gem. Stewartia can be purchased locally at many nurseries, including Weston Nurseries and through mail order sources such as RareFind Nursery (www.rarefindnursery.com).

By Joan Butler

Japanese Umbrella Pine: A Living Fossil for the Winter Garden

One of the most beautiful evergreens for the winter garden is the Japanese Umbrella Pine (Sciadopitys verticillata), a slow-growing specimen that always attracts attention. It is an elegant conifer with long, thick, lustrous needles and a long and fascinating history.

The Umbrella Pine is actually not a pine at all.  It is a coniferous evergreen that is now classified in its own family, the Sciadopitaceae. The Umbrella Pine can be traced to the Triassic period, some 250 million years ago, when the continents were joined and much of North America was near the Equator. At that time, the Japanese Umbrella Pine and its then-numerous relatives flourished in what is now Eurasia, northern Europe and northern North America. But as the continents moved and flowering plants replaced conifers, the Umbrella Pine’s range and species diversification shrank. Today, this once successful family is reduced to just one species growing in the cool cloud forests of central Japan at elevations of 1,500-3,000 feet.

Enthusiasts and collectors of unusual and historical specimens consider the Umbrella Pine a “living fossil”. A living fossil is any living species of plant or animal with no known close relatives outside of the fossil record. Growing a living fossil in the home garden is one way to help preserve rare or endangered plant species since it increases their geographic range. Other trees that are considered “living fossils” include the ginkgo (Ginkgo biloba), Dawn Redwood (Metasequoia), and Monkey Puzzle Tree (Araucaria araucana).

Francis Parkman, a Boston historian with a passion for gardening, was the first to grow this conifer outside Japan.  In 1861, he was sent the first Umbrella Pine - along with the first Japanese maples to be grown in America - by George Hall, an Oriental trader. Parkman named this unusual conifer Japanese Umbrella Pine because the whorl of stiff flattened needles at the end of each shoot resembles the spokes of a Japanese umbrella.

Although the Umbrella Pine has a narrow growing range (Zones 5-7), it is an ideal tree for much of New England. It enjoys moist, acidic, well-drained soil, full to part sun, a sheltered location, and is not subject to diseases or pests. In nature, it grows as a 120-foot tall tree with a dense, symmetrical growth habit and reddish-brown bark that exfoliates in shreds. In the garden, it is very slow growing - often making only 6 inches of growth a year to a height of 25-40 feet. The luxuriantly rich evergreen needles are 2 to 5 inches long. As the tree ages, 3- to 6-inch-long oval-shaped, brown pine cones will appear. Even the pine cones are slow growing – they take almost two years to mature after pollination. Because of its slow growth rate, the Umbrella Pine can be used in rock gardens. It makes a unique addition to the home landscape as a specimen or lawn tree, or even as part of a foundation planting. Attractive, unusual, but somewhat pricey, this long-lived conifer will be a prominent focal point in any garden setting.

My own Japanese Umbrella Pine is less than 18 inches tall, and currently invisible thanks to the many snowstorms we’ve had this winter. My husband is an avid fossil collector who dreams of establishing a dinosaur museum someday and I have promised to landscape the museum with a Triassic period garden. Perhaps my Umbrella Pine will be large enough to feature as a specimen by then.