Growing ajuga is an excellent way to quickly fill in an empty area in your garden. A member of the mint family, it shares that herb's ability to spread by sending out runners, creating ground cover that suppresses weeds and protects against soil erosion. It's also a decorative plant, producing colorful spikes of flowers and distinctively dark foliage even in shady areas where other plants might fail to thrive. Ajuga is easy to grow, making it a popular choice for hassle-free coverage of otherwise difficult spots in a garden.
Ajuga seeds are widely available online and at garden centers, where they'll often be sold under the alternative name of bugleweed. They're reliable germinators and don't need any special attention to coax them into becoming seedlings. It's possible to start your ajuga patch off simply by scattering the seeds over bare soil, but for more control over spacing, it's a good idea to sow seeds in small pots before transplanting the seedlings to their final home.
Ajuga is a tough plant that can handle most conditions so long as it's not sitting in soaking wet soil. It grows best in soil with a neutral pH, although it can cope with acid levels as low as 4.5 pH. The key point to consider when planting ajuga is that it will rapidly spread if left to its own devices, so choose a spot where it won't out-compete other, less vigorous plants. Also avoid planting ajuga next to lawns, or you might find your carefully nurtured turf is quickly overrun. Ajuga's shade tolerance and rapid spread means it's a perfect choice for ground cover where grass isn't a realistic option.
Although ajuga will flower most reliably in full sun, it will cover the ground more quickly in partial or full shade. To balance out these two behaviors, try planting it in a part of your garden that receives four to six hours of morning sun followed by some cooling shade in the afternoon.
Young ajuga plants should be given around an inch of water a week until they're established. After that, they can usually flourish using only natural rainfall, although in periods of drought they should be watered whenever the top 2 inches of soil dry out. It's best to water ajuga with a light hand — it can survive short periods of dryness unharmed but will easily rot in damp, humid conditions.
Ajuga isn't a heavy feeder and usually doesn't need fertilizers. If your soil is particularly poor, an all-purpose fertilizer can be useful, but only add nutrients if your ajuga is failing to thrive rather than as a matter of course.
Ajuga is hardy in USDA zones 3 through 9, so it can survive mid-winter temperatures as low as -40°F. That said, there is some slight variation among the varieties, so check before planting.
Ajuga doesn't require pruning for healthy growth. However, you should keep an eye on how fast your ajuga plants are spreading to keep them under control. Digging up the runners from the plant’s boundaries will contain the spread, and this should be done once or twice a year. Removing the fading flowers throughout the growing season will keep the plant tidy while preventing it from self-seeding.
Within its hardiness zones, ajuga will happily tolerate the worst that winter can throw at it. In colder areas, adding mulch around the plant's base in late fall can help protect against unusually frosty snaps, but in most cases there's no need. Individual leaves may dry out and scorch in particularly harsh winds, but the plant itself is rarely troubled and growth will return once the weather warms.
Ajuga is a natural spreader, but you can speed up ground coverage by dividing established plants in spring or fall. Simply dig up a clump of ajuga and cut it into sections using a sharp, clean knife. Each new part should contain a portion of the root system so it can make a full plant once replanted.
The two most common ajuga diseases are both fungal. Powdery mildew may appear on the foliage, starting as white spots that can spread across the whole plant if left untreated. In most cases, making sure the plants aren't overcrowded and have plenty of air circulation is enough to ward off mildew. Crown rot is another fungal problem that destroys the parts of the plant just above and below the soil surface, and it's usually the result of overwatering or soil with poor drainage.
Ajuga isn't a target for many pests, but watch out for aphids, which feed on the sap — heavy infestations can weaken the plant. These tiny green, white, or black flies can be washed away with a garden hose; alternatively,spraying with a mixture of water and horticultural soap can immobilize and suffocate them.
Thanks to its love of shade, ajuga is a good choice for growing underneath trees and shrubs, where it will provide more interest than grass or mulch. It can also be used to fill gaps between stepping stones or pavers, suppressing weeds while strengthening the underlying soil. The lower-growing varieties of ajuga complement many container plants, providing year-round foliage among more seasonal flowers.
If the rapid growth and potential invasive behavior of ajuga doesn’t seem the best fit for your garden, other less vigorous ground cover plants include creeping thyme, periwinkle, dead nettle, and sweet alyssum.
Ajuga isn't known to be toxic to people, pets, or wildlife. However, it does have a bitter taste that deer in particular seem to avoid. A border of ajuga around your garden may work as a deterrent if you have a deer problem in your area.
More than 300 varieties of ajuga offer a wide range of foliage and flower colors. Try growing the Black Scallop variety to enjoy its purple-black leaves alongside vibrant blue blooms, or Bronze Beauty, which features metallic-tinged foliage. Dixie Chip's leaves are a mixture of white, pink, and green, while Catlin's Giant grows towering flower spikes up to 12 inches long.