beloved conifer: microbiota decussata

F ILL IN THE BLANK: ___________ is an evergreen ground-covering conifer that can tolerate some shade and minus-30 or colder. I guess I gave away the answer in the headline, but you get the idea: It’s an unusual set of traits. And Microbiota decussata, the so-called Siberian cypress, distinguishes itself just a little further, turning a bronzy-purplish cast in winter.

Unlike the ubiquitous groundcover junipers, Microbiota is lacier-textured, almost Arborvitae-like, and arches in a somewhat graceful manner. My oldest plants are more than a foot tall at the tallest spots, and more than 8 feet across (I have read that they can get to 10 or even 12 feet wide and a couple of feet high). It is good for holding banks, which is how I use it on my hilly site in part shade, such as just above and beyond the pictured Buddha (if one can be above and beyond Buddha, that is).

The plant was first discovered near Vladivostok in the 1920s, above the treeline, where it survived the deep cold of Siberian winters, making it a Zone 3-hardy creature, supposedly.

Although it is a groundcover species, don’t expect it to grow in the dark: That was the mistake made at first when Microbiota reached the American market in any numbers maybe a decade ago. Saying a plant can handle some shade is different from saying it’s a shade plant; this one wants half a day of sun or more, I think, and wholesalers who propagate a lot of it say sun to part sun on their labels. In warmer zones, protection from afternoon sun is important, and in fact Microbiota isn’t a fan of the hottest zones at all.

Though Microbiota (seen above in winter color) is said to have few if any pest and disease problems, I will confess to this: I have killed a number of them, without ever learning why. What was meant to be a whole bank of Microbiota simply didn’t choose to be that way, and only about half of the ones I planted thrived. In another spot, I had the same experience. Hmmmm…was it something I did, or had this load of plants suffered some insult or injury en route to me that didn’t show itself until later?

I will never know. (A familiar refrain in gardening: You often never know; the thing just dies.) I have read about a disease-resistant cultivar–but without much detail about what it’s resistant to, and whether that matches what happened to some of my former plants. Give Microbiota well-drained but not dry soil, more sun than shade, and remember: Though it won’t happen instantly, these plants get big, so give them room.