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Plant care

Great Masterwort (Greater Masterwort) care

Astrantia major

Also called Great Masterwort, Greater Masterwort, Masterwort.

RHS H7USDA 4-7Mildly toxic to petsIndoor 60–90 cm tall and 45–60 cm wide (24–35 in × 18–24 in).

Watering rhythm

Medium indirect light (a couple of metres from a window)

Regularly — keep soil evenly moist throughout the growing season

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Light

Medium indirect light (a couple of metres from a window)

Soil

Rich, moisture-retentive, humus-rich loam

Humidity

Moderate to high

Temp

-20 to 22°C

Pet safety

Mildly toxic to pets

Mature size

60–90 cm tall and 45–60 cm wide (24–35 in × 18–24 in).

Care at a glance

Light

Picture the indirect light an east-facing window gives mid-morning — that's the brightness great masterwort grows fastest in. Grows best in light to partial shade with a few hours of morning sun; strong afternoon sun in combination with dry soil causes premature leaf scorch and early dormancy. You'll know it's right when new leaves come out the same size and colour as the established ones. Smaller, paler new leaves = move closer to the window.

Watering

Aim for regularly — keep soil evenly moist throughout the growing season for great masterwort, but treat that as a starting point rather than a rule. A south-facing summer windowsill will dry the pot twice as fast as a north-facing winter room. Lift the pot; if it feels noticeably lighter than it did wet, water it. Does not tolerate drought; water deeply whenever the top 2–3 cm of soil dries. In hot summers, mulch around the crown to retain soil moisture.

Soil and pot

Great Masterwort grows best in rich, moisture-retentive, humus-rich loam. Incorporate well-rotted organic matter at planting; soil should hold moisture but not become waterlogged. Can tolerate the margins of boggy ground. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Great Masterwort sits happiest at around Moderate to high humidity and -20 to 22°C (-4 to 72°F). Naturally a plant of cool, humid mountain meadows; it prefers cooler, moister conditions and does not thrive in hot, dry summers. If you keep the room above year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed great masterwort sparingly. Apply a balanced general fertiliser or top-dress with well-rotted compost in spring; avoid high-nitrogen feeds, which reduce flowering. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on great masterwort in the Growli community. Each is annotated with the most common cause so you know where to start.

  • Powdery mildew — A white powdery coating on leaves is common in dry conditions or where air circulation is poor; keep plants well watered, thin surrounding plants, and remove affected foliage.
  • Astrantia leaf miner — Larvae of the leaf-mining fly cause brownish patches and pale tunnels in leaves, typically appearing in early summer; remove and dispose of affected leaves promptly.

Propagation

Divide clumps in early spring or early autumn (the most reliable method); can also be grown from fresh seed sown in autumn with cold stratification (2–3 months at 2–5°C). Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Great Masterwort is mildly toxic to pets. Astrantia major is not listed on the ASPCA Toxic and Non-Toxic Plant database for cats or dogs. Because its safety status is unconfirmed, it is classified here as mildly-toxic as a precaution. Consult a vet if a pet ingests any part of the plant. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Great Masterwort care — frequently asked questions

What is the common name for Astrantia major?

Astrantia major is most commonly called Great Masterwort, but it is also known as Great Masterwort, Greater Masterwort, Masterwort. The names refer to the same species, so care instructions for Great Masterwort apply identically to anything sold as Greater Masterwort.

How much light does great masterwort need?

Great Masterwort grows best in medium indirect light (a couple of metres from a window). Grows best in light to partial shade with a few hours of morning sun; strong afternoon sun in combination with dry soil causes premature leaf scorch and early dormancy.

How often should I water great masterwort?

Water great masterwort regularly — keep soil evenly moist throughout the growing season. Does not tolerate drought; water deeply whenever the top 2–3 cm of soil dries. In hot summers, mulch around the crown to retain soil moisture. The finger-test (or lifting the pot to feel its weight) beats a fixed weekly calendar because pot size, light, and season all change how fast the soil dries.

Is great masterwort toxic to cats and dogs?

Great Masterwort is mildly toxic to pets. Astrantia major is not listed on the ASPCA Toxic and Non-Toxic Plant database for cats or dogs. Because its safety status is unconfirmed, it is classified here as mildly-toxic as a precaution. Consult a vet if a pet ingests any part of the plant.

What USDA hardiness zone does great masterwort grow in?

Great Masterwort is rated for USDA zone 4-7 and RHS hardiness H7. Outside that range, grow it as a container plant that overwinters indoors before the first hard frost.

Great Masterwort deep-dive guides

Every aspect of great masterwort care, each with its own calibrated guide:

Featured in these plant shortlists

Great Masterwort qualifies for 6 curated Growli shortlists — each one filtered objectively from our structured plant-care library, so the selection is consistent and checkable:

Related guides

Great Masterwort is also known as Great Masterwort, Greater Masterwort, and Masterwort.