Photo by Mary Henry: Because they’re happy in a limited root run, tolerant of a good deal of drought, have handsome and colorful foliage and spectacular late summer flowers, sedums make excellent container plants.
Photo by Mary Henry: Because they’re happy in a limited root run, tolerant of a good deal of drought, have handsome and colorful foliage and spectacular late summer flowers, sedums make excellent container plants.

Like many garden stories, this one begins in England. If you’ve traveled through the country villages of the sceptered isle, you’ve probably noticed stone houses with stone shingles on their roofs. Atop these shingles, you may have seen low plants growing with waxy leaves, sometimes in bloom. These are stonecrops (sedum angelicum). Their presence is no accident. As has been the practice for centuries, these native plants were encouraged to grow there. They act as insulation, keeping indoor heat in during winter and repelling summer heat. They provide food and some habitat for birds and insects. They even have uses in naturopathic medicine. Their decorative component is a byproduct.

Once a stone shingled roof was put in place, small sprigs of the stonecrops were tucked in among the roofing stones. They root easily with a minimum of water and organic material, but as they grow, they trap bits of debris. Birds provide manure for fertilization. Their fine roots pull moisture from the stone and store it in their leaves. The starts expand into clumps, and the clumps spread, forming a mat on the roof.

Native to Western Europe, these little stonecrops belong to the sedum genus. With over 600 species, sedums span eight pages in Liberty Hyde Bailey’s encyclopedic Hortus Third. The common name stems from the fact that they are often found crawling over stones in spots of the landscape where they receive ample sunlight and are open to catching rainfall when it arrives.

In the last century or two, other low-growing, mat-forming sedums have been brought into cultivation and, in some cases, even added to the gardens of English stone roofs. These, too, are now referred to as stonecrops. Nurseries abound with these small sedums, usually sold in 4-inch pots. You’ll find them in a vast assortment of leaf shapes and shades of color: blue, gray and silvery blue, light and deep burgundy, gold and assorted greens. My all time favorite is sedum spathulifolium, our Northwest native with its tightly packed rosettes of foliage in bluish gray, tinged with reddish purple. The variations make for a kaleidoscope of color and form when put together. The combinations are only limited by one’s imagination.   

It’s important to note, here, that not all members of the sedum genus have this low, sprawling growth pattern. In October of 2020 this column carried a story about S. spectablie (reaching a height of 18 inches) and S. telephium (a 2-footer). The Mexican native S. oxypetalum stretches up to 3 feet. The cascading branches of S. morganianum (commonly called Donkey’s Tail) can dangle 3 to 4 feet, beloved for hanging planters, a much-loved houseplant for sunny windows.

Because they’re happy in a limited root run, tolerant of a good deal of drought, have handsome and colorful foliage and spectacular late summer flowers, sedums make excellent container plants. An assortment of stonecrops, massed in a shallow pot, makes for an excellent, low-maintenance show for a sunny patio. You can go away for a weekend, even a week, and not worry about watering. There are a few tricks to growing them successfully, however: a good soil mix, judicious pruning, regular, albeit infrequent, watering, and feeding.

Stonecrops want loose soil so that their hair-like roots can go down and spread out, anchoring them and searching for water, which they’ll store in their leaves. A good soil consists of two parts potting soil to one part poultry grit. Poultry grit is the crushed granite, sold in bags in farm supply stores. It is fed to chickens and turkeys to fill their gizzards for grinding food. As these stonecrops grow, tip prune them to keep the plants thick and bushy. Do this in the spring when they emerge from their winter hibernation, giving them time to set flower buds. Water plants well weekly. Feed them with a liquid fertilizer, mixed at half strength, every other week, late April to October.

A number of years ago, I put together the pot in the photograph above. In the center I used the upright, stocky sedum “Chocolate Drop.” I wanted to use a dark red, rounded leaf and a serrated blue leaf around the base. What are they? I really don’t know. The blue one might be S. “Sunset Cloud,” the red one could be S. “Voodoo.” There are hundreds of named varieties and always new ones coming onto the market. The two here came from a friend who had them. I snipped off about seven or nine shoots (always uneven numbers for good luck) and trucked them into the pot. They are so easy to get started. A year later, I was snipping them back and giving starts away.

About 25 years ago, I’d salvaged an old, cracked birdbath. Using a masonry bit on my electric drill, I made two drainage holes in the bottom of the bowl, then filled it with the potting mix. Off at the nursery, I bought one of everything I saw … all colors and forms. Not only was the bowl large, accommodating a vivid assortment of plants, the pedestal elevated the show to just below eye level, giving it even more impact.

At that time Rosemary Verey was living. The vaunted British garden designer and author published over a dozen garden books and, among other noteworthy clients, she’d designed for Prince Charles at Highgrove and Elton John. Rosemary and I had been friends since 1985. I’d visited her often at her famous garden, Barnsley House. She always blocked off a few days to visit my family and me when she was in North America.

On one of those visits, she walked into my entry garden and spotted the birdbath. She stopped, suddenly, upon seeing the stonecrop-filled birdbath. Her arms went straight, down and slightly out, fingers stretched out, palms flat and facing forward (her customary reaction to seeing something that surprised and delighted her).

After a pause she shouted out, “It’s a basket of gems!” My buttons popped.

I’m warming up to repeat that defunct birdbath trick again. Anyone out there have a cracked birdbath to unload? Better yet, having read this, use it (or some other container) to produce your own basket of gems.