Fertilising guide
How to fertilise Coris-Leaved St John's Wort (Hypericum coris)— schedule & NPK
Also called Coris-leaved St John's wort, Heath-leaved St John's wort.
More about coris-leaved st john's wort
About Coris-Leaved St John's Wort
Hypericum coris · also called Coris-leaved St John's wort, Heath-leaved St John's wort · flowering
Hypericum coris is a compact, mound-forming, semi-evergreen subshrub native to the southwestern and central Alps and northern Italy, where it colonises sunny limestone rocks and scree at elevations up to 2,000 m. It produces whorls of narrow, heath-like leaves on wiry stems and bears clusters of small golden-yellow, cup-shaped flowers in summer, making it an elegant choice for rock gardens and gravel beds. The single most important care point is sharp drainage — permanently wet soil will kill it, particularly in winter. Per the ASPCA, Hypericum (St John's wort) is toxic to cats, dogs, and horses, with hypericin as the toxic principle.
Growth habit: Low, mound-forming, semi-evergreen subshrub with erect wiry stems and whorled linear leaves.
What fertiliser coris-leaved st john's wort actually wants — and why
Coris-Leaved 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 coris-leaved 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 coris-leaved 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 coris-leaved st john's wort:
Apply a light top-dressing of balanced granular fertiliser in spring; avoid high-nitrogen feeds that promote soft, frost-susceptible growth. 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 coris-leaved 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 coris-leaved st john's wort
Half strength is the safe default for coris-leaved 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 coris-leaved 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 coris-leaved st john's wort watering schedule.
Signs you are over-feeding coris-leaved st john's wort
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for coris-leaved 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 coris-leaved 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 coris-leaved 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 coris-leaved 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 coris-leaved 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 coris-leaved st john's wort — frequently asked questions
What fertiliser does coris-leaved 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. Coris-Leaved 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 coris-leaved st john's wort?
Apply a light top-dressing of balanced granular fertiliser in spring; avoid high-nitrogen feeds that promote soft, frost-susceptible growth. Apply a light top-dressing of balanced granular fertiliser in spring; avoid high-nitrogen feeds that promote soft, frost-susceptible growth. 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 coris-leaved st john's wort?
Half strength is the safe default for coris-leaved 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 coris-leaved 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 coris-leaved 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 coris-leaved st john's wort?
Flush the pot of coris-leaved 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
- Coris-Leaved St John's Wort care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water coris-leaved 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 least yellow water lily
- How to fertilise unbranched bur-reed
- How to fertilise common club-rush
- All 10153 fertilising guides in the Growli library