Rock garden at the National Aviary is a tapestry of texture and color

Len Lehman is walking through the meticulously manicured rock garden in front of the National Aviary on Pittsburgh’s North Side. Every so often, he bends down to pull a tiny weed from among the gravel next to one of his treasured plants.

Len Lehman is past president of the Allegheny Chapter of the North American Rock Garden Society. He’s proud of this four year old rock garden the group cares for at the National Aviary on Pittsburgh’s North Side. There’s been a rock garden in one form or another since 1952.

There’s been a rock garden here in one form or another since 1952. This one is only in its fourth season, but looks like it’s been here for decades. It’s tended by the Allegheny Chapter of the North American Rock Garden Society, of which Lehman is past president. He’s been captivated by these plants for many of his 73 years.
“I’m a retired biology teacher, and whenever you teach plants, you better learn how to make it interesting,” he says with a smile.
Some of the varieties he finds fascinating come from alpine or arctic tundra.
“Most of them are big flowers on small plants in order to attract pollinators because they only have about three weeks to get their seeds formed,” he says. “When you put them together in a rock garden, they really show off. It’s just amazing how big the flower is in relationship to the plant.”
But there are more than 300 different plants in this diminutive garden, and many could be seen in a more conventional home garden.
A rock garden, he says, is simply a way to add plants to a particular rock design. This type of garden dates back to the 1600s when they were used around castles to stop people from climbing up the wall. Rock gardens soared in popularity during the early 1900s.

This low growing penstemon (Penstemon rupicola) is one of the treasures growing in the rock garden at the National Aviary. The garden is cared for by the Allegheny Chapter of the North American Rock Garden Society.

As he strolls the garden, Lehman proudly identifies some of his favorite and easy to grow plants.
“One that’s really neat is a western native called penstemon,” he says. This creeping variety with soft purple flowers is Penstemon rupicola and is perfect for a rock garden because it’s only a few inches tall.
“They are also good for hummingbirds and pollinators because of the tube-shaped flowers,” Lehman says.
Blue creeping phlox cascades across the stones and a bright greenish yellow sedum called ‘Angelina’ is evergreen providing interest year round. There are clumps of bright red and yellow miniature columbines named ‘Tiny Bells’ that are loaded with blooms.
Bright yellow luminescent flowers stand 18 inches above deep green mottled foliage. When asked if the plant was actually a weed, Lehman laughs and says, “You can define that two different ways, a weed is an unloved flower or a weed is a plant growing where it’s not supposed to.
“Hawkweed is a relative of dandelion,” he says. “Some people would consider it a weed, some people would not.”
Pulsatilla can have purple, red, pink or yellow flowers and are followed by soft, airy seed heads. The spring bulbs are fading, but return reliably growing in this well drained soil. It’s a surprise to see alpine asters, which bloom now, filled with purple flowers and yellow centers; they will persist through June.

This creeping phlox is in full bloom and grows in the rock garden at the National Aviary. The garden is cared for by the Allegheny Chapter of the North American Rock Garden Society.

The garden is a tapestry of textures and colors which change with the seasons, something many locals enjoy as the explore this hidden gem. Mark Wade and Nancy McMahon were walking their beagle, Maggie, past the garden, slowing down to enjoy the flowers.
“I just think it’s one of the most beautiful gardens I’ve ever seen,” Wade says. “Even though it’s small in size, it is just grand. It’s just a little piece of heaven, I love it. I just find peace here.”
Lehman says anyone can create a rock garden, which can be quite small. “They do like to have fairly well drained soil,” he says. Sand, gravel and loam were mixed by the city parks department and used as the growing medium for these beds.
Small shrubs also fill the garden, adding verticality color and interest.
“One of the other nice things about rock gardening is they make ideal places if you like conifers,” he says. There are gold junipers and a weeping cedar of Lebanon, which he calls, “one of our pride and joys.”
As he looks over large and small strategically placed stones surrounded by beautiful blooms, Lehman reveals what he gets out of working in the rock garden.
“Just the sheer satisfaction of having a public garden that people enjoy,” he says, plus the beauty of being able to watch something grow.
While looking down at those pretty purple penstemons, he quotes America’s first female landscape architect, Elizabeth Lawrence, who said, “All gardeners become rock gardeners, because gardening is an art and rock gardening is the ultimate form of art.”

Columbine ‘Tiny Bells’ is covered in blooms is in the rock garden at the National Aviary. The garden is cared for by the Allegheny Chapter of the North American Rock Garden Society.

Rock garden show
The Allegheny Chapter of the North American Rock Garden Society will hold its 49th annual show on May 7 at Soergel Orchards in Wexford. The event is free and open to the public.
Plant sales start at 9 a.m. and the show itself begins at noon. The society offers advice for creating rock gardens and there are a variety of garden demonstrations too. Anyone can enter a plant in the juried show also.
Details: trib.me/RockGardenShowSunday
Doug Oster is the Tribune-Review home and garden editor. Reach him at 412-965-3278 or doster@tribweb.com or via Twitter @dougoster1. See other stories, blogs, videos and more at everybodygardens.com.