Lady's mantle is an absolutely fantastic plant for a partially shady border. It can also make a great ground cover. Lady's mantle (Achemilla mollis) was used during the Middle Ages as a medicinal herb. Today, however, it is used as a foliage plant in the landscape ... and rightly so. The foliage is quite impressive. The 12-inch leaves are gray-green with scalloped edges. In fact, lady's mantle got its name from how the leaves resembled the hem of a lady's cape. The leaves also have tiny little hairs on them, which capture the dew in the morning and seem to sparkle like diamonds in the early morning sun.
Lady's mantle will produce greenish-yellow or lime-green fluffy blooms in the early summer, which are quite pretty in their own right. If you, however, do not want your lady's mantle to reseed, you should cut the flowers back. This will also help to encourage a bushier growth as well as a second flush of blooms. You should also cut back the foliage when the plant starts to look a bit shabby. (Cut it back at least by half usually about mid-summer.) You can, though, allow the flowers to go to seed if you are using lady's mantle as a ground cover and wish it to spread, which it definitely will. If it starts getting out of control, just pull out the volunteers.
Lady's mantle grows to be 1-2-feet tall and has an 18-inch spread. It likes moist, well-drained soil in partial shade. In the more northern areas in which it is hardy (zones 4-8), it can handle full sun. Further south, though, it needs more shade and extra watering. (Mulching to aid moisture retention is a good idea, too.) Lady's mantle is generally pest- and disease-free; however, in the hot southern regions of the United States, fungus can sometimes be a problem when water is left on the leaves overnight after late afternoon showers.
There are a couple of different varieties available in which you might be interested. One is A. vulgaris, which is also the variety used as a medicinal herb during medieval times. This variety has greener leaves with less hair. A second variety that can really add interest to your garden is called 'Alpine lady's mantle' (A. alpine). This variety is only 5-6 inches tall and has smaller leaves than many of its cousins. The leaves, however, have white edges, which look really nice in shady areas. There is one other version of A. mollis known as 'Thriller,' which you might like to include in your landscape as well. This version has larger leaves and a more erect growth.