As a perennial, the Masterwort plant, also known as Astrantia, can be grown in USDA hardiness zones 4 through 7. Part to full shade is ideal for this plant. Astrantia thrives in soil that is well-drained and rich in organic matter. At maturity, Astrantia can reach one to two feet (31-61 cm). Astrantias can be found in an array of hues. There are a lot of tightly packed florets on the masterwort plant, which is why the flowers are so unique. Using this technique makes the flower look like a firework or a star. Due to their close relationship to carrots, the leaves of Astrantia resemble both Italian parsley and carrots.
USDA Hardiness Zone 4-This is the transitional zone between Zones 3 and 5, and it is usually found near the center of the United States. Plants in this zone can withstand brief exposure to cold temperatures but should be relocated to warmer climates if exposed to cold temperatures.
USDA Hardiness Zone 5– Most people live and work in this area, but it isn’t the only one. During short periods of moderate cold, plants in this zone can withstand the cold. If the plants are exposed to cold for a long time, they should be moved to warmer areas.
USDA Hardiness Zone 6- Evergreens and hardy shrubs are seen in this zone. It also includes some of the northernmost locations for USDA zones. Most people can do without supplemental heat in winter! The plants withstand brief exposure to cold much better than those found in Zone 5 or 7 but should not be planted too close together due to shallow root systems requiring additional space between these generally larger-sized specimens growing on a trellis system with plenty of ventilation.
USDA Hardiness Zone 7- This zone extends from the point of extreme cold in Zone 6, though most areas are too cold for zone 8 or 9. Plants with shallow root systems or little winter protection should be carefully considered when planting here, as some plants struggle to survive long exposure to low temperatures over time.
Hardiness Zones 3 – 5: Plant in September
In Zones 3 – 5: Plant from mid-September to late October. If the original frost date has not passed by some time in September, resow with hybrid seeds for a fall crop of vegetables or flowers and reestablish healthy seedlings enough days before the first predicted freeze (the “founder”) that they are probably beyond it while still cool enough to survive a moderately deep winter freeze.
Hardiness Zones 6 – 7: Plant in October
In Zones 6 – 7: Plant from mid-October to late November. Adjust planting dates as conditions dictate, depending on weather and local climate. If the frost date has not passed by some time in October, resow with hybrid seeds for a fall crop of turnips or beets and reestablish healthy seedlings enough days before the first predicted freeze that they are probably beyond it while still cool enough to survive a moderately deep winter freeze.
USDA Zone 4a: to -34.4 °C (-30 °F)
USDA Zone 4b: to -31.6 °C (-25 °F)
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
Astrantia Planting Care
- Astrantia thrives in part-shade, well-drained soil that is constantly moist and rich in organic matter. Dappled shade and morning sun are ideal for the plant thriving in these conditions. The plants will not produce more blooms as they would in full sun in full shade.
- If rain is inadequate to keep the soil moist, this species must be irrigated. Because of its adaptability and tolerance for some standing water, it could be used as a border plant for a bog garden.
- Most of the Upper Midwest is a good place to grow it, as long as nighttime temperatures don’t exceed 70°F (21.1°C).
- Early spring and mid-summer fertilization are possible but probably unnecessary in well-fertilized soils.
- This plant has few pest issues, but aphids and slugs may attack it.
- Plant astrantia seeds in the spring or fall, or divide established plants. To germinate, seeds need to be coldly stratified for two to three months, which can be accomplished most easily by sowing them directly in the garden in the early fall. However, they can be started indoors about six months before being transplanted outdoors after the last frost. The germination process will be boosted by scarring.