By Melinda Heigel, NC State Extension Master GardenerSM volunteer of Durham County
This is the second installment in an ongoing series called Plant Detective, where we uncover science-based information on strange and mysterious sightings in the plant world.
Details of the flower and stem of the mystery plant I recently discovered on a walk with dogs Baby and Cole, assistant plant detectives. While it looked like a cross between a bee balm and lamb’s ear, it was something I’d never seen before! (Image credit: Stan Shebs CC BY-SA 3.0; Linda De Volder CC BY-NC-ND 2.0)
On one of our daily dog walks, I recently stumbled across a plant I simply could not identify. It was a gorgeous mounded shrub with fuzzy, soft, gray-green leaves–the kind you just have to touch–and a lot like the lamb’s ear (Stachys byzantina) or the garden sage we all know. Graceful arching stems sported multiple flower clusters along each stem, much like snapdragons (Antirrhinum majus). And the vivid yellow flowers encircling the stem looked like a silly court jester’s hat. In a more appropriate botanical reference, they appeared similar to the bee balm flower (Mondara spp.). What was this cool plant? An online search of the NC Extension Gardener Plant Toolbox turned up a positive ID: Jerusalem sage (Phlomis fruticosa).
Characteristics and Growing Conditions for Jerusalem Sage
(Left to right) The large stand of Jerusalem sage I encountered was nearly 5 feet tall and 5 feet wide and acted as a small hedge for the homeowner’s landscape. Once the flowers drop, textural seed heads continue to provide visual interest. Deadheading the plant can encourage longer bloom time. Seed heads eventually turn brown and can be a food source for birds in the fall. (Image credit: Melinda Heigel)
A member of the mint family (Lamiaceae), Jerusalem sage is native to arid yet temperate Mediterranean regions like Greece, Italy, Cyprus, and Albania. It is also naturalized in southwest England and parts of California. This plant has a mounding habit and can function like a shrub or subshrub. Depending on the variety, it can grow up to 4 feet wide and 5 feet tall. Silvery-green velvety leaves are around 5 inches long and have a pleasant scent. Tall vertical stems rise from the plant and support whorled flowers repeating along its arches. And while the 2-to-3-inch flowers have no scent, they are spiky and eye-catching. The plant I stumbled across had a brilliant yellow flower. Other species of Phlomis have a soft pink bloom.1
You can see why the plant’s common name includes the word “sage.” Its soft velvety leaves resemble that of our edible herb garden sage (Salvia officinalis) and other ornamental Salvia plants, even though they are not related. (Image credit: Melinda Heigel)
While these plants have the reputation of being fairly adaptable in many soils, well-drained soils are are a must. This perennial prefers full sun and can perform in part sun; planting it in shade will often result in a leggy plant short on its spectacular spring and summer blooms. In our region of central NC (Zone 8), Jerusalem sage is evergreen; in Zones 5-7, it’s deciduous.
Jerusalem sage has a long list of positive attributes. Overall, this plant is low maintenance and resilient. While weeks of drought like we’ve recently experienced might call for some supplemental watering, it needs little extra irrigation once established. It is heat tolerant and prefers leaner soil (read no fertilizing). It grows quickly but generally is a well-behaved inhabitant in the garden, only requiring you to prune to maintain shape and lightly in late winter before spring growth commences. If you are willing to do the work, deadheading spent flowers in the spring means you will enjoy additional flowering, thus extending the bloom cycle throughout the summer.
With only leafhooper insects as a potential threat, Jerusalem sage has no serious pests or pathogens. Here’s a big bonus–this plant is both deer and rabbit resistant, and its flowers are attractive to bees, butterflies, and hummingbirds. Spent seed heads can also provide food for songbirds.
How to Use Jerusalem Sage in the Landscape
This plant can wear many hats in the garden. It’s suitable for containers or as a stunning specimen plant. Planted en masse, it could make a great year round statement. As in the landscape where I first saw it, it can serve as part of a mixed screen planting bordering a yard. Given its height, it’s probably best as a “back of the border” plant in a mixed bed.
In terms of garden design, I can see this versatile plant looking right at home in a cottage-style garden of glorious native perennials like purple coneflower (Echinacea purpurea), sunflowers (Helianthus spp.), butterfly milkweed (Asclepias tuberosa), and scaly blazing-star (Liatrus spicata). Equally, I can see it as a stunner alongside other water-wise plants in a xeriscape of agave, yucca, and cacti like our native eastern prickly pear (Opuntia humifusa).
I hope you’ve discovered a new plant right alongside me this week. Given the challenging environmental changes we continue to see, I am planning on giving this easy-to-grow and drought-resistant plant a try. And while I haven’t seen Jerusalem sage at local nurseries yet, I found many online resources where the plant is readily available.
As always, keep an eye out next time you are walking. Who knows what intriguing things you might see! With late summer and fall or the horizon, what plant mystery will we solve next?
Notes
1–The genus Pholmis has many varied species, so make sure to research thoroughly those other than the Phlomis fruticosa discussed here. Required growing conditions will vary per species.
2–Xeriscaping is type of landscape design that keeps water conservation in mind and requires minimal supplemental water once plants are established.
Resources and Additional Information
For more on Jerusalem sage, see NC Extension Gardener Plant Toolbox.
https://plants.ces.ncsu.edu/plants/phlomis-fruticosa
For more information on water-wise landscape design, check out NC Department of Environmental Quality’s site on xeriscaping.
For more on native and non-native drought-resistant plants, see NC Botanical Garden’s plant list as well as our former blog post “Ten Plants That Can Take the Heat.”
https://durhammastergardeners.com/2022/05/18/ten-plants-that-can-take-the-heat/
Article Short Link: https://wp.me/p2nIr1-4Nj
Assistant plant detectives Baby and Cole are always on the case. (Image credit: Melinda Heigel)