Fertilising guide
How to fertilise Hound's-tongue (Cynoglossum officinale)— schedule & NPK
Also called Hound's-tongue, Gypsy Flower, Dog's Tongue, Common Hound's-tongue.
More about hound's-tongue
About Hound's-tongue
Cynoglossum officinale · also called Hound's-tongue, Gypsy Flower · flowering
Hound's-tongue is a biennial or short-lived perennial native to Europe and temperate Asia, widely naturalised in North America. It thrives in dry, disturbed ground, roadsides, and chalk grassland in full sun with free-draining, low-fertility soil. The most important care fact for cultivated settings is to avoid over-watering and rich soil, which cause lax, floppy growth. This plant is toxic to pets and livestock due to pyrrolizidine alkaloid content.
Growth habit: Rosette-forming biennial that sends up a branched, leafy flowering stem in its second year, covered in hooked bristles.
Watch for — Failure to flower (etiolation): Insufficient sunlight or over-fertile soil causes large, soft leaves but no flowering stem in the second year — move to a sunnier, poorer site.
What fertiliser hound's-tongue actually wants — and why
Hound's-tongue 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 hound's-tongue: 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 hound's-tongue, 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 hound's-tongue:
Do not fertilise — poor soil is essential; any added nitrogen produces coarse, non-flowering plants. 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 hound's-tongue 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 hound's-tongue
Half strength is the safe default for hound's-tongue — 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 hound's-tongue first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the hound's-tongue watering schedule.
Signs you are over-feeding hound's-tongue
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for hound's-tongue:
- 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 hound's-tongue
- 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 hound's-tongue care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of hound's-tongue 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 hound's-tongue
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 hound's-tongue — frequently asked questions
What fertiliser does hound's-tongue 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. Hound's-tongue 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 hound's-tongue?
Do not fertilise — poor soil is essential; any added nitrogen produces coarse, non-flowering plants. Do not fertilise — poor soil is essential; any added nitrogen produces coarse, non-flowering plants. 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 hound's-tongue?
Half strength is the safe default for hound's-tongue — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding hound's-tongue 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 hound's-tongue 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 hound's-tongue?
Flush the pot of hound's-tongue 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
- Hound's-tongue care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water hound's-tongue — 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 dryopteris carthusiana
- How to fertilise dryopteris intermedia
- How to fertilise athyrium angustum f. rubellum 'lady in red'
- All 10153 fertilising guides in the Growli library