Masterworts are wonderful, underused shade plants. They have divided foliage that resembles the foliage of some perennial geraniums, and heads of flowers surrounded by spiny-looking bracts. The flowers appear in shades of pink, white, and red in summer, and they are good cut flowers.
- Common name: Masterwort
- Botanical name: Astrantia major
- Zones: 4 to 7
- Size: To 3 feet tall
- From: Areas of Europe and Asia
- Family: Umbelliferae (carrot family)
- Sun: Partial to full shade
- Soil: Moist, but well-drained soil rich with organic matter and that does not dry out.
- Moisture: Water in times of drought.
- Mulch: Lay a 2- to 3-inch-deep layer of organic mulch over the soil around the plants to help the soil conserve moisture and to suppress weeds. Use winter mulch only after the soil has frozen.
- Pruning: Cut plants back in autumn after freezing temperatures arrive or in spring before plants begin to grow.
- Fertilizer: Fertilizer is generally not necessary in soils that are rich in organic matter. If desired, use a balanced fertilizer in spring.
- Division: Divide plants in spring or autumn.
- Aphids: These small insects often appear in large numbers on new growth. Spray them off daily with a stream of water; they will not attack a plant after being knocked off. Use an insecticidal soap or neem-oil-based spray if infestations are severe.
- Fungal diseases: If portions of the plant rot or have spotted leaves, the plant may be suffering from fungal disease. To prevent these diseases, try to avoid wetting the plants' foliage, especially after mid-afternoon. It is also helpful to divide plants so that the clumps do not become especially large. This will ensure good airflow, which also discourages these diseases.
- Powdery mildew: This disease tends to appear in mid- to late summer. Affected leaves have a grayish powdery covering. The leaves then drop off. To deter the disease, prune the plant to keep good air flow, and avoid wetting the foliage in afternoons and evenings.
- Slugs/Snails: Slugs and snails tend to eat at night, chewing up leaves. They leave slick, slimy trails behind the next morning. To deter them, try surrounding plants with a ring of horticultural grade diatomaceous earth or laying down slug bait. Some people have found success with laying copper strips around plants, but this does not seem to work for everyone. If slugs are not particularly numerous, set out shallow containers of stale beer at ground level. Slugs, attracted to the beer, crawl into it and drown.
- Astrantia major ‘Alba': A cultivar that has green foliage and white flowers. To 3 feet tall. Zones 4 to 7.
- Astrantia major‘Gill Richardson': A cultivar that has green foliage and dark red flowers-one of the darkest red of masterworts. To 3 feet tall. Zones 4 to 7.
- Astrantia major ‘Hadspen Blood': A cultivar that has green foliage and dark red flowers. To 3 feet tall. Zones 4 to 7.
- Astrantia major ‘Lars': A cultivar with green foliage and reddish flowers over a longer period than most other masterworts. To 2½ feet tall. Zones 4 to 7.
- Astrantia major‘Roma': A cultivar that has green foliage and soft pink flowers. To 3 feet tall. Zones 4 to 7.
- Astrantia major ‘Ruby Cloud': A cultivar that has green foliage and red-purple flowers. To 3 feet tall. Zones 4 to 7.
- Astrantia major ‘Sunningdale Variegated': A cultivar that has green foliage with creamy edges. Pale pink flowers. To 3 feet tall. Zones 4 to 7.