Posts tagged ‘winter’

Update on the Eastern Bluebird Trail

Eastern bluebird nesting boxes

The green roof Eastern bluebird nesting boxes before installation on the trail.

In 2012, the Smithsonian Gardens Green Team developed an Eastern Bluebird Trail at our greenhouse complex in Suitland, Maryland. The trail of ten paired nest boxes was designed to support and expand the year-round resident Eastern Bluebird population. By the end of the 2013 nest season, the bluebird population had expanded to about thirty birds.

What happened in 2014? We began monitoring the trail in March, looking for the first signs of nesting behavior. The monitoring continued through July and in that time, no Eastern Bluebirds have been seen at or around the greenhouse complex. We believe the resident population migrated to another location due to a harsh winter of repeated deep Arctic cold blasts starting in late November and persisting through March. In addition to the cold, we believe the bluebirds did not have enough food to support their population.

American beautyberry and flowering dogwood

American beautyberry (Callicarpa americana, top) and flowering dogwood (Cornus florida, bottom) are bluebird favorites!

Bluebirds rely on fruit for more than thirty percent of their diet. In the winter, when insects are scarce, they depend on persistent fruits more than at any other time of year. The SG Green Team is committed to planting more native tree and shrub species around the facility to provide a sustainable winter habitat for the birds. Planting trees and shrubs not only provides food for birds but also provides shelter from harsh winds and cold temperatures.

-Sarah Hedean, SG Green Team Member

December 11, 2014 at 10:30 am Leave a comment

Wildlife in the Winter Garden


American holly (Ilex opaca).

Did you know Smithsonian Gardens joined Audubon International’s Cooperative Sanctuary Program? The goal is for the gardens and greenhouses at the Smithsonian to be designated as a Certified Audubon Cooperative Sanctuary. To become certified, Smithsonian Gardens has developed, implemented, and documented the results of an environment management plan in five key areas: site assessment and environmental planning, wildlife and habitat management, water, resource management, and outreach and education. We believe that Smithsonian Gardens has met (or in some cases exceeded) Audubon International’s environmental management standards in all five areas. We are looking forward to a site visit from an Audubon International staff member to verify Smithsonian Gardens submission.

Below is a list of plants that you can find in the Smithsonian Gardens that are native to the mid-Atlantic region and provide food and shelter to wildlife during the winter months.

  • Ilex glabra, also called inkberry, is an evergreen shrub with black fruit called drupes. The fruit, attractive to birds, appears September through March. You can find this shrub in the Urban Bird Habitat Garden at the National Museum of Natural History.
  • Ilex opaca, known as American holly, can be found on the south side of the Smithsonian Castle in the Enid A. Haupt Garden. This large evergreen tree provides nesting opportunities for birds and small mammals as well as bright red berries to sustain our feathered friends during the cold winter months.
  • Ilex verticillata is a deciduous holly often called winterberry. Birds really seem to enjoy these beautiful berries so don’t forget that winterberries are dioecious, meaning that the berry-producing female plants need a male winterberry nearby to produce fruit. Look for Ilex verticillata on the north side of the National Air and Space Museum due east of the entrance.
  • Lindera benzoin is called spicebush because of the spicy smell of the leaves when crushed.  We grow this tree for its year-round wildlife value. This tree is a host plant for the Spicebush Swallowtail butterfly and the fruit is eaten by songbirds. You can find this understory shrub in the landscape of the National Museum of the American Indian as well as in the Butterfly Habitat Garden at the Natural History Museum.
  • Rhus typhina ‘Dissecta’ or staghorn sumac as it is commonly called is not only a picturesque plant but a source of reddish brown seeds that are consumed by many birds and small mammals throughout the winter months. The staghorn sumac is also a host and nectar plant for both moths and butterflies which is why you can find it in our Butterfly Habitat Garden.
Rhus typhina 'Dissecta'

Staghorn sumac (Rhus typhina ‘Dissecta’)

For more information on native plants for wildlife habitat:

For more information about the Audubon International’s Cooperative Sanctuary Program: 

Shelley Gaskins, Smithsonian Gardens Horticulturist, Green Team Member 

January 24, 2014 at 7:30 am Leave a comment

Winter Interest in the Garden

Just because it is winter does not mean that our gardeners or gardens get a rest.  Smithsonian Gardens welcomes visitors year-round.  These visitors include many tourists but also wildlife, as our gardens serve as an important urban habitat for birds, insects, and mammals.

Within our gardens you will find many plants that add winter interest beyond our impressive annual displays of pansies, violas, and kale.  Important garden features in this bleaker season include berries, grasses, seedheads, stems, bark, evergreens, and even some flowers.

Fruit and berries are a great way to brighten up a winter landscape and many serve as an important food source for birds.

Winter berries

Berries you will find in our gardens include (clockwise from upper left) Red Chokeberry (Aronia arbutifolia); American Holly (Ilex opaca); Firethorn (Pyracantha ‘Mohave’); Southern Bayberry (Morella cerifera); Beautyberry (Callicarpa dichotoma); Carmine Crabapple (Malus x atrosanguinea); and Winterberry (Ilex verticillata)

When selecting plants for winter berries note whether they are deciduous or evergreen.  The pointed rich green leaves of the American Holly above create a great contrast to the bright red berries while the Winterberry (Ilex ‘Sparkleberry’) below looks better with a solid backdrop like an evergreen to best stand out.

Winter berries

Winterberry (Ilex ‘Sparkleberry’)

Grasses and sedges add texture to our gardens in winter and some add great color as well.  Many of the grasses also provide seeds for birds in winter and nesting materials come spring.

Winter grasses

Some of the grasses and sedges you will find on our gardens include (clockwise from upper left) Leather leaf sedge (Carex buchananii ‘Red Rooster’); Switch Grass (Panicum virgatum ‘Cloud Nine’) [close-up and full plant]; Orange New Zealand Sedge (Carex testacea); and Pink Muhlygrass (Muhlenbergia capillaris) [pictured in November and January]

Seedheads create interest with varying shapes and textures and make a dynamic feature in winter as they mature and disperse.


Seedheads and pods that draw attention in our gardens include (clockwise from upper left) False Indigo (Baptisia australis); Purple Coneflower (Echinacea purpurea); Okra (Abelmoschus esculentus); Common Milkweed (Asclepias syriaca); Goldenrod (Solidago spp.); Whitehair Leather Flower (Clematis albicoma); and Upland Ironweed (Vernonia glauca)

Remember these seedheads are the result of earlier flowers from plants that have multiple seasons of interest.  Some of these seeds are now food sources for birds,  but their flowers were nectar sources, or some had foliage that fed caterpillars, in earlier seasons.  Take the Wild Senna (Senna marilandica) below, for example. It is a wonder native plant with nectar-providing pea-like flowers and is a host plant for sulfur butterflies in the summer.

Wild Senna (Senna marilandica)

Wild Senna (Senna marilandica)

Differing barks and branches also play a significant role in enhancing our gardens in winter.  Peeling barks of birches, brightly-stemmed twig dogwoods, and the towering dry stems of perennials can all become dominant features in the winter.

Bark and Branches

Some of our most striking stems in the gardens are seen with (clockwise from upper left) Paper Birch (Betula papyrifera ‘Renci’); River Birch (Betula nigra ‘Heritage’); Hollow Joe Pye Weed (Eutrochium fistulosum); Tatarian Dogwood (Cornus alba ‘Bud’s Yellow’); Coral Bark Japanese Maple (Acer palmatum ‘Sangokaku’); Crape Myrtle (Lagerstroemia ssp.); Red Twig Dogwood (Cornus sericea ‘Baileyi’); and Paperbark Maple (Acer griseum)

Evergreens are a key element to add structure in gardens during the winter.  There are a variety of evergreens available with a myriad of shapes, textures, and even colors.  Evergreens can be needled conifers but also broadleaf trees and shrubs and even some perennials hold their foliage in the winter months.  They also provide important cover and shelter for many species in winter.

Evergreen Perennials

A small sampling of our many needled evergreens include (clockwise from upper left) Eastern Redcedar (Juniperus virginiana ‘Burkii’); Umbrella Pine (Sciadopitys verticillata); Irish Yew (Taxus baccata ‘Fastigiata’); Japanese Cedar (Cryptomeria japonica); and Scotch Pine (Pinus Sylvestris ‘Burghfield’)

Broadleaf Evergreens

Some of the more dominate broadleaf evergreens in our gardens are (clockwise from upper left) Southern Magnolia (Magnolia grandiflora); Lantanaphyllum Viburnum (Viburnum x rhytidophylloides); Sweetbay magnolia (Magnolia virginiana); English Cherry Laurel (Prunus laurocerasus ‘Otto Luyken’); Common Boxwood (Buxus sempervirens); and Oregon Grape (Berberis aquifolium)

Lastly we can’t forget about winter flowers.  There is not much that blooms at this time but those flowers that do truly give us reason to celebrate.  They are also important nectar source for late and earl- season pollinators.

Winter Flowers

Blooms you can spot in Smithsonian Gardens in winter are (clockwise from upper left) Lenten Rose (Helleborus x hybridus); Common Witchhazel (Hamamelis virginiana); Sasanqua Camellia (Camellia sasanqua ‘Jean May’); Paperbush (Edgeworthia chrysantha); Stinking Hellebore (Helleborus foetidus); and Beale’s Mahonia (Berberis bealei)

I encourage you to take a walk through our gardens on a nice winter day and see what interesting plants you spot.

-James Gagliardi, Smithsonian Gardens horticulturist

January 7, 2014 at 7:30 am 2 comments

Hellebores: Jewels of Winter, Part II

Last week Smithsonian gardens Horticulturist Janet Draper introduced us to some of the most beautiful of the winter flowering plants, Hellebores. Here are a few more of her favorite picks for your home garden:

Helleborus niger 

One of the new cultivars that I have been most impressed with are new varieties of Helleborus niger,  a.k.a the ‘Christmas Rose.’  I had never been impressed with Helleborus niger in the past, but the selection ‘Joseph Lemper’ has really changed my opinion.  It is marketed as part of the Helleborus Gold Collection (HGC) from Heuger nurseries in Germany.  The Joseph Lemper in the Ripley Garden started producing numerous 2-2 1/2” flowers on sturdy tall stems held well above the foliage in late NOVEMBER and it is still producing new flowers in late February!   I am not sure if this form is sterile or not, but either way this cultivar is a showstopper for the winter garden.

Hellebore 'Pink Frost'

Helleborus x ballardie ‘Pink Frost’

Helleborus  x ballardiae ‘Pink Frost’

Another member of the HGC series is Helleborus  x ballardiae ‘Pink Frost’.  This beauty starts blooming in February and will continue for at least a month.  It has lovely upward-facing pink flowers which turn a deeper shade of pink as they age.  The foliage is gorgeous, with lovely white veining and red stems.   My plants are still young, but I am really impressed with what is showing so far!

There are many other exciting new cultivars hitting the market, including some from local breeders like David Culp in Pennsylvania, Barry Glick in West Virginia and Judith and Dick Tyler in Southern Virginia.  There are new selections which are double flowered, or possess dramatic markings, enlarged nectarines, upward facing flowers… oh the madness!

I have been slowly adding more and more of these winter gems to the Ripley Garden and currently have nineteen different varieties.  Some are still quite small and will not bloom for a year or two since they take some time to get established, but all are worth the investment of time and money to brighten your winter garden.

-Janet Draper, Horticulturist

March 11, 2013 at 9:00 am 1 comment

Hellebores: Jewels of Winter, Part I

Most people think that winter is a “dead time” in the garden, but they could not be more wrong. In a climate as mild as Washington DC (officially a zone 7b, but Mother Nature doesn’t seem to like being pigeonholed), little signs of spring start to appear as early as January.

I’d like to share my love affair with the jewels of the winter—Helleborus.  Hellebores are members of the Buttercup family (Ranunculaceae), and are shade loving, evergreen plants which bloom during the winter months. Wait—it gets even better—deer don’t find them to be particularly tasty!

It used to be that the most commonly found hellebores in nurseries were the Christmas rose, (Helleborus niger) and the Lenten rose (Helleborus hybridus).  Other species were available but sorely under appreciated  Times have changed, and thanks to breeders, the diversity of Hellebores on the market is quite amazing,

Here are a few of my favorite Hellebores growing in the Smithsonian Mary Livingston Ripley Garden:

Helleborus foetidus

A long time favorite of mine has always been Helleborus foetidus, or the Stinking Hellebore. What a cruel name for a gorgeous plant! Helleborus foetidus has finely-cut fingerlike evergreen foliage which thrives in shady conditions. The real show begins in October when chartreuse flower stalks start emerging above the foliage, taunting you with the promise of flowers. The small lime green bells finally unfurl in late January or February, demure clusters of little green bells edged in raspberry.

One interesting fact about Hellebores is that the flower ‘petals’ are actually modified leaves so even after the flower starts seed production, these ‘petals’ remain attractive for two to three months.

The only maintenance required for this hellebore is to cutting off the flower stems once they start to look tatty. Or, if you have enough plants, cut off the flowering stems before the seed pods ripen, otherwise they will self sow to produce a large colony.

Corsican Hellebore

Helleborus argutifolis, ‘Corsican Hellebore’

Helleborus argutifolius

Another favorite species of mine is Helleborus argutifolius, or the Corsican hellebore. It also produces lovely chartreuse flowers, which are striking against its coarsely-toothed blue-grey foliage. The flower opens entirely and is outward facing to display the prominent yellow stamens very clearly. The one challenge I have with the Corsican Hellebore is that the two-foot stems flop, leaving a gaping bald spot in the center of the clump—nothing a little discrete staking can’t hide. Like Helleborus foetidus, the Corsican hellebore is caulescent (flowers are produced on the same stem as the foliage) so once the flowers begin to look tatty or you don’t want any more plants, remove this entire stem down to the ground, and any other stems that look rough after the winter.

Hellebore 'Lenten Rose'

Hellebore x hybridus, ‘Lenten Rose’

Helleborus x hybridus

One of the classic hellebores on the market is Helleborus x hybridus, the Lenten rose, with blooms ranging from white to pink. Due to the seed grown variability it is always best to purchase plants in flower if you want to know what you’re getting. Otherwise, enjoy the surprise!

-Janet Draper, Horticulturist

March 5, 2013 at 9:00 am Leave a comment

Never Enough Time

Chestnut Hill Gardens, Litchfield, Connecticut, 2010. Collection of the Archives of American Gardens.

Chestnut Hill Gardens, Litchfield, Connecticut, 2010. Collection of the Archives of American Gardens.

I am waiting – waiting patiently for blustery, winter weather to begin. Gardening books are neatly stacked by the couch, magazines are piled by the bed and I have even book marked several websites to explore. I have a folder of plant lists I collected during symposiums and lectures I attended. I want to research the plants that caught my eye and determine if they are as outstanding as promised or just a one shot pretty-boy? I bought a packet of graph paper, colored pencils and an architect’s ruler; I am ready to draw a detailed design for my backyard redo. I wanted to do all these jobs this summer, but I never seemed to have enough time. So, the books piled up, the websites were left unexplored and the plants are sitting in pots waiting for me to draw a proper design.

Oh, I accomplished a lot this summer – every day was filled with weeding sessions, I developed numerous lectures, and occasionally I even read sections of chosen books. But there was never enough time to be as organized or thorough as I wanted to be. I cut corners everywhere. I installed plants without researching growth habits, let weeds go to seed, missed the second pruning of the espaliered fruit trees and sometimes the lectures I gave were not as snazzy as I wanted them to be.

But during the busy growing season I didn’t despair – at least not too much. I knew disagreeable winter weather would eventually come and I would be forced to stay inside. As the wind howled and the temperatures dropped outside, I would bundle in a blanket and take the time to read, research and draw.

Winston Garden, Far Hills, New Jersey, circa 1965. Collection of the Archives of American Gardens.

Winston Garden, Far Hills, New Jersey, circa 1965. Collection of the Archives of American Gardens.

Okay, winter is here! Now I’ll stay inside and start one of those saved projects. Although, I hope I have more diligence than I did last year. Every time I would sit down to read a book my dog would prod and whine and try to convince me that the weather really wasn’t all that bad. Couldn’t we please go take a walk? So I would put the book down and brave the cold weather. Another day I’d go outside to take measurements for the garden’s new design and notice all the winter weeds. The tape measure would slide back into my pocket and I would spend the afternoon pulling weeds in the brisk air. If I sat at the computer to do some cyber-surfing, I would remember all the outdoor chores that just could not wait for another day.

Do you notice a trend? The piles of books that I never have time to read didn’t accumulate overnight. I really do want to read them, but they sit undisturbed (or barely ruffled) because no matter what the weather is like I would rather be outside than inside. That’s probably why I am a gardener instead of a movie star (okay, maybe there are a couple of other reasons). Writing deadlines keep me in, pouring rain keeps me in – but for the most part, you’ll find me outside; playing in the dirt, walking the dog or drinking a glass of wine and staring at the garden beds imagining what could be.

Sometimes I feel guilty ignoring my indoor activities, but I really shouldn’t. I may not be reading about other people’s gardening experiences, but I am accumulating plenty of my own. The winter walks may keep me away from the computer, but they help me notice nature’s nuances. I become a more sensitive gardener when I am aware of the subtleties that unfold throughout the seasons. When I sit on the deck relaxing with a glass of wine, I may not be physically sketching ideas, but I am daydreaming, developing my “perfect” garden design – no eraser needed.

So I am not totally resigned from completing my noble plans; I’ll keep stacking books, piling magazines and book marking websites. I don’t think my behavior will change this year, but who knows? In the meantime, I’ll keep waiting for a string of bad weather.

See you in the garden -maybe even if it is raining.

-Cynthia Brown, Horticulture Collections Management & Education Manager

March 4, 2013 at 9:00 am 3 comments

Winter Gardening Tips

The most important winter task is to take stock of your garden’s successes and failures. Mental notes are good, journal entries are better. There are plenty of mistakes to make, why repeat one?

Did you faithfully fertilize your garden during the growing season? If so, where are the leftovers? Don’t store them on your potting bench or your garden shed; bring them into an area that will remain above freezing. Some liquid fertilizers and pesticides become ineffective after freezing and thawing.

The winter months are the perfect time to take stock of the condition of your garden. Bonaire, West Orange, New Jersey, circa 1930. Ellen Biddle Shipman, landscape architect. Collection of the Archives of American Gardens.

The winter months are the perfect time to take stock of the condition of your garden. Bonaire, West Orange, New Jersey, circa 1930. Ellen Biddle Shipman, landscape architect. Collection of the Archives of American Gardens.

Take advantage of warm winter days; clean up garden debris. Pests and diseases can overwinter on and in dropped fruit, vegetables, leaves and stems. Keep the garden clean and reduce the chance for re-infections. Being neat has the added benefit of reducing the amount of chores necessary in the spring.

When you are cleaning up the garden, don’t cut back the stems of subshrubs: lavender, Russian sage, perennial salvias, etc. The stems provide protection and a bit of insulation for the crown and the dormant buds. Wait till you see new signs of growth in the spring before pruning.

Talk a walk around the garden periodically to check on plants that may have “popped out” of the soil. Fluctuating soil temps – freezing and thawing – can push the perennials and pansies you planted in the fall right out of their holes. Dig the hole a bit deeper, replant and then smooth mulch around the plant’s base. This should keep the plant firmly grounded.

Use branches of pruned evergreens to protect tender perennials from wintry blasts. Maybe your rosemary plant will finally survive the winter!

Careless use of deicing products can damage both the home and the environment. To prevent damage to your home and the environment, choose a deicer carefully. Use deicers according to the directions listed on the package, if possible use even less than is recommended. Do not use fertilizer to melt ice and snow – the nitrogen and phosphorus in fertilizer can harm your local streams and the Bay. Plant damage caused by deicers can often be treated by soaking the affected area with 1-inch applications of water three to four times in the spring. As an alternative to deicers – use sand, ashes, or kitty litter to improve traction on icy areas.

Remember to water plants on warm days in January, February and March especially if there has been a dry autumn. Evergreen plants, particularly those planted in the fall, are most susceptible to desiccation.

Remove snow before it can accumulate by sweeping the branches upward with a broom to lift off the snow without further stressing the limbs.

Motivated to grow ‘green’? Use organic seed in next year’s garden. Check with the National Sustainable Information Service ( for a list of suppliers of Certified Organic seed. Several seed catalogs located in Mid-Atlantic States appear on the list, including: Southern Exposure Seed Exchange ( in Mineral, Virginia, Landreth Seed Company ( in Baltimore, Maryland, and Seedway ( in Elizabethtown, Pennsylvania.

-Cynthia Brown, Horticulture Collections Management & Education Manager


February 19, 2013 at 9:00 am Leave a comment

A Gardener’s Resolutions

Tulips and other spring flowers at the Henry Francis du Pont Winterthur Museum and Gardens, circa 1930. Collection of the Archives of American Gardens.

Tulips and other spring flowers at the Henry Francis du Pont Winterthur Museum and Gardens, circa 1930. Collection of the Archives of American Gardens.

When the ball dropped in Times Square this January did you make a New Year’s Resolution? Shedding excess weight, increasing physical activity, and expanding intellectual awareness are popular choices.  Noble resolutions, but my favorite resolutions usually center around garden improvements. Coincidentally, while I am improving the garden I am also increasing my physical activity, shedding winter-gained pounds and increasing cerebral activity – and loving every minute.

Resolution #1: This year my garden will be perfect so I will stop apologizing when friends visit. My perfect garden is designed while daydreaming. Daydream designing is a simple pastime with outstanding results. All changes and improvements are given consideration. I can move shrubs, rearrange paths, and add ponds, sheds, and arbors repeatedly without sweating or reaching for Ben-gay. I can rethink combinations and add new plants and I don’t have to worry if the plant is accessible or expensive. Outlandish ideas that seem impossible usually develop into stunning features. The design process would be aided with photographs and complete records, but that is…

Resolution #2: I will photograph my garden during all seasons so I can remember highlights, mistakes and colors. On one side of the steps leading to my front door I planted exquisite, apricot-colored species tulips. I would like to add more, but I don’t know the cultivar and I can’t remember exactly where they are located.  To rectify this, all I would have to do is take a picture while they are blooming. I planted them 8 years ago; so far I haven’t made any new additions.

Resolution #3: I will visit _______ garden. They have the best examples of ______ and it would be fun to see how they _____ . Fill in the blanks. I have a list of gardens a mile long that I want to visit, meet the staff, and borrow ideas. I know it is important to keep your garden maintained, spend time with the family and occasionally go grocery shopping, but I also must satisfy my curiosity and see what other gardeners are creating. Besides, I may discover the name of my cute little apricot tulip.

Resolution #4: I will continue my quest for gardening trivia. Conversing at cocktail parties used to be so difficult. But since I started collecting interesting gardening facts I can talk all night. You would be surprised how many people are curious about the sex lives of aphids or how an amorphophallus is pollinated. You can acquire an amazing amount of trivia by attending lectures, subscribing to numerous journals, and reading horticultural books. Of course you’ll also improve your gardening skills, but that is a bonus.

Four resolutions, not too overwhelming; Happy New Year!

-Cynthia Brown, Horticulture Collections Management & Education Manager

January 22, 2013 at 9:00 am 1 comment

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