Fertilising guide
How to fertilise Large Masterwort (Astrantia maxima)— schedule & NPK
Also called Greater Masterwort, Maxima Masterwort.
More about large masterwort
About Large Masterwort
Astrantia maxima · also called Greater Masterwort, Maxima Masterwort · flowering
Large Masterwort is a robust herbaceous perennial native to the Caucasus, bearing larger-than-average pink pincushion flower heads surrounded by prominent spreading bracts from early to mid-summer. Larger than Astrantia major, it suits shaded woodland gardens and moist borders. Treat as mildly toxic around pets.
Growth habit: Clump-forming herbaceous perennial, rhizomatous
What fertiliser large masterwort actually wants — and why
Large Masterwort is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for large masterwort: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed large masterwort, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For large masterwort:
Top-dress with garden compost in spring. A balanced slow-release fertiliser can be applied at the same time for richer soils. Avoid over-fertilising, which produces lush foliage and fewer flowers. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when large masterwort is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for large masterwort
Half strength is the safe default for large masterwort — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water large masterwort first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the large masterwort watering schedule.
Signs you are over-feeding large masterwort
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for large masterwort:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding large masterwort
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full large masterwort care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of large masterwort with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for large masterwort
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising large masterwort — frequently asked questions
What fertiliser does large masterwort need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Large Masterwort is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed large masterwort?
Top-dress with garden compost in spring. A balanced slow-release fertiliser can be applied at the same time for richer soils. Avoid over-fertilising, which produces lush foliage and fewer flowers. Top-dress with garden compost in spring. A balanced slow-release fertiliser can be applied at the same time for richer soils. Avoid over-fertilising, which produces lush foliage and fewer flowers. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for large masterwort?
Half strength is the safe default for large masterwort — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding large masterwort look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding large masterwort year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of large masterwort?
Flush the pot of large masterwort with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Large Masterwort care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water large masterwort — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise new dawn rose
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- All 11687 fertilising guides in the Growli library