Moist, well-drained soil? Dappled shade? Plant these beauties
By Merabeth Steffen
OSU Ext. master gardener volunteer
Astrantia, commonly known as masterwort, is a perennial that would be at home in any cottage garden. Hardy in zones 5-7, it grows in mounded clumps 12 to 18 inches tall with blooms adding another 12 inches of height. Bloom colors include white, pink, purple or dark red, depending on the cultivar.
The leaves are 3-6 inches long and palmate,, with toothed and deeply divided lobes. The foliage is a medium green that lasts throughout the growing season and dies back after frost.
Astrantia are in the carrot family, but the bloom is different from the typical umbel produced by other members of the Apiaceae family. The 1- to 1 Ω- inch blooms consist of many tiny, tightly packed flowers surrounded by 19-20 papery bracts (colored leaves) of the same color. The star-like appearance of the flower would explain the name astrantia; it is Greek for aster or star.
Masterworts bloom in summer, and if conditions are favorable, may continue into fall. Deadheading may encourage more bloom. As cut flowers they can last 10-14 days. Because they are actually leaves, the bracts remain long after the flower has finished its bloom. This characteristic makes Astrantia suitable for use in dried arrangements.
Rich, moist, but well drained soil with a neutral pH in part shade is where Astrantia prefers to grow. Morning sun is best, with dappled shade the rest of the day. They are ideal planted streamside, in open woodlands or in a mixed perennial border. Plant them along a garden path where the detail in their flowers is easy to see.
To propagate, clumps of masterwort can be divided in early spring or fall. They will also reseed, but be aware that seedlings of hybrids will not be true to the parent plant. If planting seed, it should be done in fall since the seed needs two to three months of cold stratification to germinate. I have allowed my plants to reseed and my patch of Astrantia continues to expand.
Astrantia are native to Switzerland and Austria and are often grown in European gardens. Until the 1990s when Dutch breeders developed new selections, they were rarely used in U.S. gardens. I became familiar with them by reading about them in British gardening magazines. Today, a variety of cultivars are readily available through U.S. nurseries.
Masterworts combine well with other shade and moisture-loving plants such as ligularia, astilbe and ferns. Mine are planted near a clump of yellow alliums, a colorful contrast to my mauve Astrantia. They also grow in the shade of a red maple notorious for sucking the ground dry during periods of low rainfall. I keep them well mulched and water occasionally and they seem to do just fine.
For photos and more information, including a list of cultivars go to: http://go.osu.edu/astrantia.