Alchemilla mollis (Lady’s Mantle) is probably a well-known plant to many readers here. A perennial border classic, it is celebrated for its magnificent scalloped foliage and its delicate chartreuse-yellow flowers rising on wands above the main clump of leaves. It’s a great edging plant and an attractive visual filler among other flowers.
The photo at left is the ‘Thriller’ variety in its second year, grown from one-gallon pots. I’ve grown both the standard Alchemilla and the ‘Thriller’ variety and, on balance, I prefer ‘Thriller’. Descriptions of both varieties can vary in publications or on the internet, but, in my experience, ‘Thriller’ is a larger plant whose leaves are distinctly green rather than gray-green.
The two reasons for making ‘Thriller’ the Plant of the Month are its incredible cold-hardiness and its ability to flourish in miserable soil. Not only did the pictured Alchemilla plants survive an absolutely brutal winter, when they started to put out new growth in spring, they rapidly achieved full size, despite growing in heavy clay. It’s rare to find any perennial that looks its best the second year after planting.
Once established, Alchemilla can tolerate dry soil when grown in light shade. It can survive full sun if planted in a northern or eastern exposure and provided with adequate water. My ‘Thriller’ plants have recently been attacked by the Four-Lined Plant Bug ( a pest that is attacking all my flowers this year), but otherwise these plants are generally pest-free and disease-free. Lady’s Mantle blooms in June and is hardy in Zones 3-7. If the flowers begin to weight down the plants, they can be cut for use in arrangements.