Masterwort (Astrantia) is one of the few cut flowers that thrive in shade. This perennial bears pincushion-like flowers in late spring and early summer. The green foliage remains attractive throughout the season.
The Astrantia species that you will most likely find in the nursery trade is Astrantia major. It is native to central and southern Europe and the Caucasus and grows in shady locations with rich, moist soil, such as mountain meadows, grasslands, woodland clearings, and along stream banks. It grows in mounded clumps and spreads by stolons.
If your landscape doesn’t get a lot of sun but you still want to grow a cutting garden, masterwort is a good plant to put on your list.
Masterwort Overview
Where to Plant Masterwort
Select a planting location with partial shade, such as the north side of your house or the middle or back of shaded garden beds and borders. The soil should be rich and, very important, constantly moist but the plant does not have any specific pH requirements.
Locations near streams, rain gardens, water gardens, or areas such as ditches that tend to stay wet are ideal for masterwort. The plant will thrive in any location that gets a regular moisture supply.
Masterwort looks best if planted in groups of 3 to 10. Its upright habit makes it a perfect partner for mounding hostas and other shade garden plants.
How and When to Plant Masterwort
Plant masterwort in the spring. Dig a hole at least twice the diameter of the nursery pot and just as deep. Place the plant in the center of the hole and backfill with original soil. Tamp down the soil and water immediately to remove any air pockets. Continue watering the new plant until you see vigorous new growth.
Space plants 15 to 18 inches apart.
Masterwort Care Tips
As long as its moisture requirements are met, masterwort is a low-maintenance plant.
Light
This woodland plant prospers in part shade: filtered shade all day or morning sun with shade during the hottest part of the afternoon. If you live in a cool-summer climate where the temperature rarely peaks past 75 degrees F, you can grow masterwort in sunnier spots as well as shade.
Soil and Water
The soil should be moist and rich in organic matter. If your ground includes a lot of sticky clay or sand that causes soil to dry up quickly, amend it with a liberal amount of organic matter before planting. Masterwort tolerates slightly acid, neutral, and slightly alkaline soil (pH 6.1 to 7.8).
If the soil is not naturally moist at all times, you will need to water masterwort regularly, especially during hot, dry periods. This plant doesn't tolerate drought well, so you may find it blooms less and displays crispy brown foliage if it doesn't get enough moisture over the summer.
Spread a 2- to 3-inch layer of organic mulch such as compost, shredded wood, or pine needles around the plant base to preserve soil moisture.
Temperature and Humidity
Masterwort flourishes in a temperate climate without temperature extremes in the winter or summer, dry desert heat, or high humidity. It is hardy to USDA Zone 4 but at the lower end of its zone range, it benefits from a layer of mulch during the winter to protect its roots from the cold.
Fertilizer
Depending on the richness of the soil it’s planted in, masterwort might not need any fertilizer at all. To give the plant a boost, fertilize it with an all-purpose garden fertilizer for ornamentals once in early spring as new growth starts and again in midsummer.
Pruning
Removing flowers as they fade extends the bloom season. With regular deadheading, this perennial continues to bloom into July. Not much pruning is needed.
Either cut masterwort back to a couple of inches tall in late fall or early winter after frost kills the foliage or leave it standing for winter interest, then trim stems back to a couple of inches tall in early spring as new growth resumes.
Potting and Repotting Masterwort
Masterwort can be grown in containers, however, keeping the soil moist is challenging, as the soil in pots dries out much faster than garden soil. Use a high-quality potting mix and mix it with up to one-third of vermiculite to increase water retention.
Although masterwort is hardy to Zone 4, potted plants need to be insulated to protect the roots from the cold. Bury the container in the ground or place it in a large container filled with mulch, sand, or another insulating material. If you don’t want to avoid that extra effort, grow masterwort as an annual as some gardeners do.
If you grow it as a perennial, the plant needs repotting in a larger container and with fresh potting soil when the roots have filled the pot.
Pests and Problems
With the exception of aphids and slugs, masterwort is virtually free of major pests and diseases.
How to Propagate Masterwort
Masterwort is propagated by division or from seed. Starting it from seed is a lengthy process, as the seeds need two to three months of cold stratification and then take several months to germinate. Plus, if you collect seeds from a cultivar that is not open-pollinated, it will likely not produce plants that are true to the parent. Some cultivars are also protected by a plant patent.
Given this, dividing a mature clump is the better option. In the spring, just before new growth starts, dig out the clump, cut it into smaller sections with a spade or a sharp knife, and replant it at the same depth as the original plant. Keep it well-watered until you see new growth.
Types of Masterwort
‘Claret’
This cultivar of Astrantia major stands out by its dark colors, not only of the deep red flowers but also of the almost black stems. The leaves, on the other hand, are fresh green.
‘Star of Fire’
A favorite variety for cut flowers, Astrantia major 'Star of Fire' has smoky burgundy-red flowers with white centers on wiry stems.
‘Shaggy’
The ivory-white flowers of ‘Shaggy' (A. major subsp. involucrata 'Margery Fish') are not only larger than the species but also quite stunning with their papery, greenish-white collars.
‘Roma’
The exquisite tiny pink flowers of Astrantia major ‘Roma’ are silvery-pink surrounded by delicate papery bracts, rising above loose clumps of deep-green foliage.
Masterwort Companion Plants
Astilbe
For a graceful, feather accent to a moist, shady location, consider astilbe. Pretty plumes of white, pink, lavender, or red flowers rise above the finely divided foliage from early to late summer. Even if astilbes never bloomed, it's worth planting them merely for their handsome foliage. In spring, new foliage often emerges bright green with blushes of bronze. The plant tolerates full sun in cooler climates, provided it has a constant supply of moisture. In drier sites, however, the leaves will scorch in full sun. Zone 4-8
Ligularia
Large, coarsely textured leaves and golden flowers make ligularia stand out in a shade garden. This perennial has two types of blossoms: tall flower spikes reminiscent of bottlebrush or loose stalks of erratic, larger, daisy-like blossoms. The plant is a moisture-lover that does beautifully at the edges of ponds and streams or any other spot with deep, rich soil that remains moist. Zone 4-9
Ferns
Ferns are excellent companion plants for shade-loving flowering plants. Their hardiness varies by species but regardless of the climate, they need protection from afternoon sun to prevent drying and leaf scorch. What all ferns have in common is a preference for rich, humus-filled soil. Some ferns spread by underground runners, which can be helpful in places where you want a dense groundcover.
Frequently Asked Questions
- Is masterwort invasive?The plant spreads by aboveground stems (stolons) and slowly fills in open spaces but it is not considered invasive.
The plant spreads by aboveground stems (stolons) and slowly fills in open spaces but it is not considered invasive.
- What’s the vase life of Astrantia?The average vase life is five to ten days. It's a gorgeous filler plant for cut bouquets and arrangements. It also makes excellent dried flowers.
The average vase life is five to ten days. It's a gorgeous filler plant for cut bouquets and arrangements. It also makes excellent dried flowers.