By Jim McCausland, Sunset Magazine
Sometimes background plants catch my eye: ones that will never get lead billing in a garden show, but which give the landscape a finished, well-covered look. Such is silver-edged horehound (Marrubium rotundifolium)—the lovely gray ground cover that edges the path in the photograph below. (For reference, common horehound is the closely related Marrubium vulgare.)
I found it in Dave and Margie Van Cleve's garden in Selah, Washington (near Yakima). They found it at High Country Gardens, where it's described in words any Westerner could love: "does well in lean, well-drained soils"; "little water once established"; "evergreen"; and "native to high, dry areas of Turkey." This is a ground cover that thrives on neglect, and in a color that goes with any other plant that happens to grow nearby.
Mature size is about a foot tall and twice as wide. The leaves are cupped and frosted around the edges with a pattern that looks like lacy embroidery (see below). High Country says the plant's insignificant flowers should be sheared off, but I'm not convinced. To me they look like beautiful little frozen explosions. Judging from the plant's description and native range, I think this would grow well in Sunset zones 2b-12, 14-23. High Country says its woolly leaves melt in a combination of high heat and humidity.
Silver-leafed horehound isn't in the Western Garden Book yet, but looks like it might be worth adding. That's where you come in. Are you growing it? If so, let me know where you live, how it's doing, and whether it shows any signs of invasiveness (common horehound sometimes gets out of hand).
