Fertilising guide
How to fertilise Tuberous Catmint (Nepeta tuberosa)— schedule & NPK
Also called Tuberous Catmint, Tuberous Catmint.
More about tuberous catmint
About Tuberous Catmint
Nepeta tuberosa · also called Tuberous Catmint, Tuberous Catmint · flowering
Tuberous Catmint is a distinctive Mediterranean species with tuberous roots, producing tall spikes of deep violet-purple flowers with showy bracts from midsummer. Its drought-adapted tuberous root system makes it exceptionally heat- and drought-tolerant. Suitable for dry gardens, gravel plantings, and Mediterranean-style borders in full sun.
Growth habit: Upright, tuberous-rooted herbaceous perennial
What fertiliser tuberous catmint actually wants — and why
Tuberous Catmint 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 tuberous catmint: 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 tuberous catmint, 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 tuberous catmint:
Do not feed regularly. A single very light application of balanced fertiliser in spring is the maximum. This is a plant of poor soils; feeding promotes disease and weak 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 tuberous catmint 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 tuberous catmint
Half strength is the safe default for tuberous catmint — 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 tuberous catmint first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the tuberous catmint watering schedule.
Signs you are over-feeding tuberous catmint
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for tuberous catmint:
- 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 tuberous catmint
- 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 tuberous catmint care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of tuberous catmint 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 tuberous catmint
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 tuberous catmint — frequently asked questions
What fertiliser does tuberous catmint 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. Tuberous Catmint 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 tuberous catmint?
Do not feed regularly. A single very light application of balanced fertiliser in spring is the maximum. This is a plant of poor soils; feeding promotes disease and weak growth. Do not feed regularly. A single very light application of balanced fertiliser in spring is the maximum. This is a plant of poor soils; feeding promotes disease and weak 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 tuberous catmint?
Half strength is the safe default for tuberous catmint — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding tuberous catmint 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 tuberous catmint 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 tuberous catmint?
Flush the pot of tuberous catmint 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
- Tuberous Catmint care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water tuberous catmint — 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 buddleja 'miss ruby'
- How to fertilise buddleja 'lo and behold blue chip'
- How to fertilise buddleja alternifolia
- All 8452 fertilising guides in the Growli library