Fertilising guide
How to fertilise Olympic St. John's Wort (Hypericum olympicum)— schedule & NPK
Also called Olympic St. John's Wort, Mount Olympus St. John's Wort.
More about olympic st. john's wort
About Olympic St. John's Wort
Hypericum olympicum · also called Olympic St. John's Wort, Mount Olympus St. John's Wort · flowering
A compact, drought-tolerant dwarf subshrub native to rocky limestone slopes on Mount Olympus and throughout the Balkans. Produces a spectacular summer display of large, bright yellow flowers up to 5 cm across from June to August. Exceptional for rock gardens, dry walls, gravel beds, and sunny alpine troughs.
Growth habit: Deciduous dwarf subshrub; erect to spreading habit with grey-green, oval to elliptic leaves; woody at the base with herbaceous annual growth; forms a neat compact mound
What fertiliser olympic st. john's wort actually wants — and why
Olympic St. John's Wort 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 olympic st. john's wort: 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 olympic st. john's wort, 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 olympic st. john's wort:
Very little fertiliser required — excess feeding promotes rank, soft growth and reduces flowering. A single light application of balanced slow-release granular fertiliser in early spring is sufficient. In very poor soils, a top-dress of coarse grit mixed with a little bone meal in spring is adequate. 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 olympic st. john's wort 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 olympic st. john's wort
Half strength is the safe default for olympic st. john's wort — 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 olympic st. john's wort first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the olympic st. john's wort watering schedule.
Signs you are over-feeding olympic st. john's wort
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for olympic st. john's wort:
- 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 olympic st. john's wort
- 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 olympic st. john's wort care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of olympic st. john's wort 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 olympic st. john's wort
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 olympic st. john's wort — frequently asked questions
What fertiliser does olympic st. john's wort 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. Olympic St. John's Wort 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 olympic st. john's wort?
Very little fertiliser required — excess feeding promotes rank, soft growth and reduces flowering. A single light application of balanced slow-release granular fertiliser in early spring is sufficient. In very poor soils, a top-dress of coarse grit mixed with a little bone meal in spring is adequate. Very little fertiliser required — excess feeding promotes rank, soft growth and reduces flowering. A single light application of balanced slow-release granular fertiliser in early spring is sufficient. In very poor soils, a top-dress of coarse grit mixed with a little bone meal in spring is adequate. 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 olympic st. john's wort?
Half strength is the safe default for olympic st. john's wort — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding olympic st. john's wort 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 olympic st. john's wort 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 olympic st. john's wort?
Flush the pot of olympic st. john's wort 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
- Olympic St. John's Wort care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water olympic st. john's wort — 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 ruellia brittoniana
- How to fertilise crown of thorns
- How to fertilise cape primrose
- All 8452 fertilising guides in the Growli library