Winter beauties, these plants are stars in the cold

December 15, 2016 | Doug Oster comments

It’s comforting to know that even Keith S. Kaiser, the executive director of the Pittsburgh Botanic Garden, still had bulbs to get in the ground when we met there to talk about plants with winter interest.

 

Keith S. Kaiser, executive director of the Pittsburgh Botanic Garden poses in a stand of 'Cardinal' red twig dogwoods which are planted in a rain garden near the Bayer Welcome Center. Red twig dogwoods are one of the plants he chooses for winter interest.

Keith S. Kaiser, executive director of the Pittsburgh Botanic Garden poses in a stand of ‘Cardinal’ red twig dogwoods which are planted in a rain garden near the Bayer Welcome Center. Red twig dogwoods are one of the plants he chooses for winter interest. Photos by Doug Oster Tribune-Review

 

This 'Cardinal' red twig dogwood is planted in a rain garden at The Pittsburgh Botanic Garden. It's one of the plants that executive director Keith Kaiser likes to use for winter interest.

This ‘Cardinal’ red twig dogwood is planted in a rain garden at the Pittsburgh Botanic Garden. It’s one of the plants that executive director Keith Kaiser likes to use for winter interest.

 

Like many of us, he’s procrastinated and is looking forward to his final planting. “I love to be able to end the garden season and look ahead when it’s time,” says Kaiser, who was appointed to the position in August.
One way to do that is thinking now about planting varieties that shine during the long winter.
“My garden just takes care of itself all winter,” he says with a smile. “That’s part of why we live in these parts of the world and appreciate the natural cycle of our lives and gardening seasons. It’s a time for us to use our minds to think about something else and our bodies.”
Kaiser appreciates the break from the garden and the joy of anticipating the first snowdrop blooms.
A rain garden just outside of the Bayer Welcome Center at the garden is filled with stunning red stems, it’s not hard to imagine how spectacular it will look with a light coating of snow.
“Red twig dogwoods have such bright, brilliant colors of all shades of reds, yellows and light green,” he says. “I think in any landscape it’s extremely important to plant those.”
The variety growing here is named ‘Cardinal.’ He also loves one called ‘Midwinter Fire.’ This plant should not be confused with the native dogwood tree (Cornus Florida). Red twig dogwoods are shrubby, multi-stemmed plants, some can reach 8 feet or taller.
“I would start with ‘Arctic Fire’ dogwood,” says Mark Osgerby, public relations specialist for Proven Winners ColorChoice Flowering Shrubs (provenwinners.com). “It has a cherry red stem so it really pops out against snow.”
“Having that interest gives you that extra little boost to get you through the winter,” Osgerby says.

ÔKarl FoersterÕ grass (Calamagrostis x acutiflora 'Karl FoersterÕ) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. This plant was part of the landscape at the Pittsburgh Botanic Garden.

‘Karl Foerster’ grass (Calamagrostis x acutiflora ‘Karl Foerster’) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. This plant was part of the landscape at the Pittsburgh Botanic Garden.

“You know what really makes a plant like that stick out is having an evergreen background or evergreens near them,” Kaiser says.
Evergreens are great background features, but there are three cultivars with golden foliage that could make them stars in their own right, Osgerby says. ‘Polar Gold’ is the biggest getting up to 15 feet tall with a pyramidal shape. ‘Filips Magic Moment’ is similarly shaped and 8 feet tall. ‘Anna’s Magic Ball’ is a space saver with the same colored foliage that’s round and only about 15 inches tall.
‘It’s a low-growing golden ball, a cool looking plant,” says Osgerby, who lives in Michigan. “It has color on it all year long and I can see it through the snow.”
Birch trees also make great background plants, Kaiser says. “The birch you might want to think about is the river birch. It has nice exfoliating bark. There are many newer varieties like ‘Heritage’ with the traditional white bark.”
A birch tree also pairs well with red twig dogwoods as it loves moist soil. The dogwood shrub is very adaptable and can take hot full sun in a dry site and also grow well in a moist area with a little shade.
“It can also be trimmed to a 3- to 4-foot informal hedge,” Kaiser says.
In front of another stand of red twig dogwoods at the Botanic Garden are a group of ornamental grasses that are thin and standing tall.
“It’s great to have grasses in our landscape, but a lot of people are tired of the breaking off of those leaves in the middle of winter and blowing all around,” he says.
That’s why so many people cut them back in the fall instead of enjoying them over the season. ‘Karl Foerster’ (Calamagrostis x acutiflora ‘Karl Foerster’) is a good choice for the landscape as it has semi-evergreen foliage at the base and a very straight upright form growing 3 to 4 feet tall.
“It adds a vertical element in the landscape any time of the year and they don’t make such a mess,” Kaiser said.
Another semi-circular bed sports ‘Pink Hair Grass’ (Muhlenbergia capillaris) with soft airy panicles tinted light pink. A long row of blue sedge (Carex glauca ‘Blue Zinger’) hugs the ground. It forms grass like mounds about 6 inches tall and twice as wide.

'Oso Happy Smoothie' is a tough landscape rose from Proven Winners ColorChoice Shrubs that has beautiful flowers in the spring, summer and fall. It also puts on a show in the winter with these hips or seed heads.

‘Oso Happy Smoothie’ is a tough landscape rose from Proven Winners ColorChoice Shrubs that has beautiful flowers in the spring, summer and fall. It also puts on a show in the winter with these hips or seed heads. Photo courtesy of Proven Winners ColorChoice Shrubs

It’s surprising to see plants in bloom this time of the year, too. Two heather plants are covered with luminescent pink flowers, the plant is only about a foot tall. When given the right conditions heathers will thrive. “They need full sun, good drainage and a slightly more acidic soil,” Kaiser says.
There’s another group of plants near the Welcome Center that put on a show in the winter and beyond.
“Oak leaf hydrangeas (Hydrangea quercifolia) have all-season interest,” he says. “Through the winter, they have exfoliating bark as well as the dried seed heads and leaves with a nice burgundy color.”
In the early summer, they put on white conical flowers that can fade to cream or dark pink and are much more reliable bloomers than the mophead varieties (H. macrophylla) many gardeners struggle to grow. One bed is filled with ‘Sike’s Dwarf’ and another is planted with ‘Snow Queen.’
“They just do well for our climate,” Kaiser says, and they are tough, too. “You’ll see them quite commonly in all kinds of commercial landscapes and that’s one clue to say, this (plant) will tolerate a difficult site.”
Hydrangea arborescens are one of the most reliable bloomers, Osgerby says, and the ‘Invincibelle Spirit’ series is one of the toughest versions of the plant. It produces pink flowers in part shade and full sun, the winter interest comes when the spent flowers are left to catch the snow. In the spring this version of a hydrangea can be cut one third of the way back as flowers are produced on new growth as opposed to putting on buds the year before. This is a plant with a cause too, $1 from the sale of every plant goes to the Breast Cancer Research Foundation. To date, Proven Winner is closing in on $1 million donated.
The containers that adorn the entrance to the Welcome Center are planted with a tall arborvitae in the center, flanked by boxwood, hellebores and Christmas fern. If gardeners want to give it a try, Kaiser has a couple of tips.
“Of course, your container needs to have drainage and can tolerate being outside,” he says. “If you want those plants to survive you want to make sure they are getting water and sunlight all winter long, so don’t tuck them underneath the overhang.”

ÔKarl FoersterÕ grass (Calamagrostis x acutiflora 'Karl FoersterÕ) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. During a snowfall some of the tall stems will arch down under the wieght of the snow for a nice effect. ÔKarl FoersterÕ grass (Calamagrostis x acutiflora 'Karl FoersterÕ) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. This plant was part of the landscape at the Pittsburgh Botanic Garden.

‘Karl Foerster’ grass (Calamagrostis x acutiflora ‘Karl FoersterÕ) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. During a snowfall some of the tall stems will arch down under the weight of the snow for a nice effect. ‘Karl Foerster’ grass (Calamagrostis x acutiflora ‘Karl FoersterÕ) is a good choice for the winter landscape as it has semi-evergreen foliage at the base and a very straight upright form growing three to four feet tall. This plant was part of the landscape at the Pittsburgh Botanic Garden.

Another indestructible plant for full sun or part shade is the winterberry holly. Most cultivars will be covered with bright red berries until the birds find them, but ‘Berry Poppins’ has golden yellow fruit.
“It’s a pretty unique plant and a favorite in our trial gardens,” says Osgerby. The plant will grow 6 to 8 feet tall.
Roses that put on red hips (seed heads) give an extra season of interest for the plant. ‘Oso Happy Smoothie’ is a long blooming, tough landscape rose with pretty pink flowers with white centers. In the winter it’s covered with red fruit that can be left in the garden to be enjoyed by gardeners and birds alike. ‘Oso Happy Petit Pink’ is a compact version that is just as hardy and floriferous, it only gets about 3 feet tall and wide.
Doug Oster is the Tribune-Review home and garden editor. Reach him at 412-965-3278 or doster@tribweb.com. See other stories, blogs, videos and more at everybodygardens.com.