Monday, September 9, 2013

Groundcover Review: Ajuga, Bugleweed

The variegated ajuga in the front border mixes nicely with some Sweet Alyssum while blocking out most weeds. 

Ajuga, Bugleweed


- Evergreen (or ever-purple or ever-variegated, depending on the variety)

- Pretty and long-lasting (at least several weeks) spikes of flowers in the springtime. UGA lists Ajuga as a good bee-forage plant, but I did not see any bees on the flowers during our (cold, wet) spring. Other sources say Ajuga can attract hummingbirds and butterflies. I didn't see any of those on the flowers either. Sigh.

- Prefers moist soil, but tolerates drought

This patch of Ajuga reptans (Bronze Beauty?) gets afternoon sun and you can see that parts of it are looking a little crispy. Ajuga genevensis seems better able to tolerate afternoon sun. So in my own experience, sun tolerance varies across different Ajuga species

- Grows in sun or shade. I have one patch growing in sun, but the patches growing in afternoon shade seem much happier.

- Does not really need any maintenance. Some sources recommend cutting back the flower stalks after the bloom is done. As far as I can tell, that's only really 'necessary' for aesthetic reasons. If you don't mind the spent bloom stalks sticking up until they fall over (and I don't) then the plant is basically zero-maintenance.

Ajuga genevensis, Carpet Bugle. Annie's Annuals says it is not stoloniferous and therefore less likely than Ajuga reptans to spread out of control. (Of course, Annie's also says the plant will flower all summer, which ours does not do, so perhaps the summer blooms are a California thing or maybe it's just that YMMV...)

- Spreads pretty quickly. I could see Ajuga perhaps working in combination with Sweet Woodruff to cover large patches of shady ground that would not need much / any mowing or other maintenance.


Not native to Southeastern U.S. Like Sweet Woodruff, Ajuga reptans is native to Europe.

- Some sources list Ajuga as being mildly invasive. For instance, the North Carolina Native Plant Society has it listed as a "lesser threat".

Here's a patch of Ajuga that I really like in morning sun / afternoon shade. It's been expanding steadily and blocking all weeds from its patch of turf between a Japanese Aucuba and an Inkberry Holly. The foliage looks good all year round and the blue flower spikes were very pretty in the spring. I'm not sure which variety of Ajuga I have here. The tag says "Burgundy Glow" but the foliage doesn't look anything like the picture of Burgundy Glow on Monrovia's website. Perhaps it is Mahogany or Black Scallop? I think Black Scallop, although it doesn't behave like the other plant that was labeled Black Scallop. Either there is a lot of behavioral and visual diversity within Ajuga cultivars or there's a fair amount of mislabeling going on...

- As with Sweet Woodruff, I could see Ajuga becoming a problem for annuals or other small perennials. Reportedly at least some species of Ajuga spread both through rhizomes and stolons, so that could make it doubly hard to control. Supposedly also may spread by seeds and can reportedly show up far away in garden beds and lawns. (Although I haven't found any seedlings yet.)

- Also like Sweet Woodruff, Ajuga may technically be evergreen, but that doesn't mean it looks beautiful all year round. In fact, I found the Ajuga looked much more tattered than the Woodruff over the winter. I think slugs like to eat the Ajuga in the cool months, because there were lots of holes in the Ajuga leaves. The slugs didn't cause any mortal wounds and Ajuga has rebounded to look lush and thick in the springtime, but it's not necessarily all that attractive in the winter months.

- Ironically, even though Ajuga can be aggressive, it can also have the opposite problem of thinning out in the center. Some sources say that it needs to be divided every 2-3 years to prevent crown rot. I haven't noticed anything that catastrophic, but some of my Ajuga species do seem to be thinning out in the middle. I've read reviews online where gardeners talk about their ajuga dying out in one place and popping up somewhere else. I think my mother had this problem with her Ajuga, where it eventually died out where she wanted it to cover ground and then showed up far away in the lawn or in some other garden bed where she didn't really want it to grow. It may be unpredictable that way.


I'm actually pretty conflicted on Ajuga. I can see its merits, but I worry that it is a little too thuggish. If it were a native plant, I probably would not be too concerned, but since it's an exotic, I worry about what natives it might suppress or displace if it were to spread beyond the garden. The fact that Ajuga is not on many invasive species lists does make me feel a bit more comfortable. That said, all four patches in my garden right now are behaving themselves and performing well. So I'm going to offer a qualified endorsement, but I'll keeping a close eye on the Ajugas in my garden and suggest you do the same in yours if you decide to plant some.