Ajuga

Family:Labiatae (Mint Family)
Genus: Ajuga
Species: reptans

If you already have Ajuga reptans established in your garden, you’re no doubt looking forward to the study in blue it will provide this spring. A wonderful characteristic of this perennial groundcover is the tendency of its blooms to appear all at once. An aura of blue that is breathtaking—particularly from a distance—seems to hover above the foliage. In full sun, the aura absolutely glows. It was, I think, to honor this effect that the common name, carpet bugle, was given to Ajuga reptans. It’s also known as bugleweed—sometimes it’s just called bugle—but no, this doesn’t denote a resemblance to any musical instrument. The Latin roots are different, with the one leading to our Ajuga bugle meaning a kind of plant. The other bugle originated from the Latin word for ox…it’s all about horns, in that case. The word Ajuga was given by none other than Linnaeus, the Swedish botanist who is responsible for our system of scientific nomenclature. Ajuga means “without a yoke” and was inspired by the fact that the sepals surrounding the buds of Ajuga are not connected. The species name, reptans, describes its growth habit: A. reptans creeps by underground stolons, growing out rather than up. A. pyramidalis, another species of the same genus, grows up, rather than out, and it does not spread by runners. Sunset Western Garden Book points out that in both A. reptans and A. pyramidalis, there are varieties named ‘Metallica Crispa’. Nursery shoppers should make sure they’ve selected the species they really want: creeping or not. This is yet another reason to become familiar with botanical names and the characteristics they represent, rather than relying on common names.

There are many other named varieties of Ajuga reptans. While the species is one of the least invasive groundcovers (even though it might creep, very tentatively, into your lawn if it’s given the opportunity), the varieties tend to be even less aggressive. They also tend to be a little more fragile and a trace more temperamental than the species, although they offer choices in bloom color as well as leaf form and color. One of the newest varieties is ‘Pink Silver’, offering silvery leaves with tinges of pink, and purple-blue flowers. It is reportedly more likely to remain true than the other variegated varieties, ‘Burgundy Glow’ and even ‘Variegata’. A. reptans ‘Bronze’ offers bronze and green leaves and deep blue flowers. ‘Jungle Green’ has the largest leaves—they’re even larger and the flower spikes are taller in shade than in sun. In the shade, the plant parts are working harder to gather what they need, so leaf surfaces are greater and flowers stretch higher. They may show off to less advantage in the shade…but Ajuga reptans will do well in sun or shade, so long as the shade is not deep. All varieties of A. reptans will work hard to establish a thick carpet of leaves. They are nearly evergreen, although in the winter their framework is more notable than their lushness. Since structure is a desirable commodity in the winter garden, A. reptans is considered to provide year-round interest in our climate.

Ajuga doesn’t like high humidity or extreme heat. It does prefer well-drained soil that’s rich in organic matter. In that preference, of course, it differs not a whit from most of the plants we have in our gardens. It does not like to dry out completely, and so I thought twice about recommending it as we head into what is certain to be a time of necessary water restrictions. However, I was able to keep a small plot of Ajuga thriving in California during a seven-year drought, using only water collected from our showers. That sort of watering technique may become even more important here in the months ahead, as we all learn how to make choices to conserve our water, that most valuable and increasingly scarce resource.

Ajuga reptans isn’t vulnerable to many pests besides slugs, who seem only to take a swipe at it on their way to the hostas. It is susceptible to root rot where drainage is poor and the soil is compacted, so make sure your soil drains well and is fluffed up with plenty of organic amendments. Powdery mildew can take over your Ajuga, particularly in late summer, where there is poor air circulation and dank, heavy soil. But most of the Ajuga maladies you might encounter can be prevented or managed with good general plant care. Feed your Ajuga twice a year, with a balanced fertilizer in the spring and one high in phosphorus and potassium in late summer; and mow off the spent flower heads after they’ve put on their show. Leaf color and interesting, crinkly surfaces will remain as either a backdrop or focal point.

Plant Ajuga reptans in the early spring, placing the plants about 8 inches apart—or 15 inches if you’ve chosen one of the big-leafed varieties. They’ll fill in quickly and soon you, too, will have a study in blue in your own yard each spring and a tidy, good-looking ground cover throughout the rest of the year.