Fertilising guide
How to fertilise Garden Catmint (Nepeta × faassenii)— schedule & NPK
Also called Garden Catmint, Blue Catmint, Faassen's Catnip.
More about garden catmint
About Garden Catmint
Nepeta × faassenii · also called Garden Catmint, Blue Catmint · herb
Garden Catmint is a mounding, aromatic perennial prized for its lavender-blue flower spikes and silver-green foliage. A sterile hybrid, it blooms prolifically from late spring to autumn if cut back after the first flush. Drought-tolerant and deer-resistant, it thrives at border edges in full sun.
Growth habit: Mounding, spreading perennial; forms neat clumps that may flop open after flowering
What fertiliser garden catmint actually wants — and why
Garden Catmint is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.
A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed.
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 garden 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 garden 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 garden catmint:
Rarely needed in the ground. A light top-dressing of balanced granular fertiliser in early spring suffices. Over-feeding produces lush, floppy growth at the expense of flowers. Container-grown plants benefit from a low-nitrogen liquid feed monthly. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.
The dormant-season rule matters more than the exact interval: skip feeding entirely when garden 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 garden catmint
Half strength is a sensible default for garden catmint — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
Feeding always goes onto already-damp soil, never dry roots — water garden catmint first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the garden catmint watering schedule.
Signs you are over-feeding garden catmint
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for garden catmint:
- Fast, soft, pale growth with diluted, less aromatic flavour.
- Early bolting (running to flower) and a bitter edge.
- Salt crust and scorched tips on container plants.
Signs you are under-feeding garden catmint
- Pale, slow regrowth after cutting and small leaves.
- A tired, stalled plant that cannot keep up with harvesting.
- Yellowing older leaves in a long-spent pot.
If the symptoms point at watering, light or roots rather than nutrition, the full garden catmint care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Pot-grown garden catmint builds up feed salts quickly — water until it drains each time and flush the pot with plain water every few weeks, especially on a sunny windowsill.
Organic vs synthetic feeds for garden catmint
Organic options
A diluted seaweed feed or worm-casting tea keeps soft growth coming without overdoing it. UK: dilute seaweed or Westland; US: Espoma Garden-tone or Neptune's Harvest. Gentle, hard to overdo, flavour-friendly.
Synthetic / liquid feeds
A balanced liquid feed at half strength through harvesting — UK: Phostrogen, Baby Bio or Westland; US: Miracle-Gro all-purpose at half strength. Fast regrowth; just do not overdo the nitrogen.
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 garden catmint — frequently asked questions
What fertiliser does garden catmint need?
A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed. Garden Catmint is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.
How often should I feed garden catmint?
Rarely needed in the ground. A light top-dressing of balanced granular fertiliser in early spring suffices. Over-feeding produces lush, floppy growth at the expense of flowers. Container-grown plants benefit from a low-nitrogen liquid feed monthly. Rarely needed in the ground. A light top-dressing of balanced granular fertiliser in early spring suffices. Over-feeding produces lush, floppy growth at the expense of flowers. Container-grown plants benefit from a low-nitrogen liquid feed monthly. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.
What strength of feed for garden catmint?
Half strength is a sensible default for garden catmint — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.
What does over-feeding garden catmint look like?
Fast, soft, pale growth with diluted, less aromatic flavour. Early bolting (running to flower) and a bitter edge. Salt crust and scorched tips on container plants. Over-feeding garden catmint with strong nitrogen is the usual mistake — it grows fast and lush but the leaves turn bland and it bolts to flower sooner, ending the useful harvest early.
Should I flush the soil of garden catmint?
Pot-grown garden catmint builds up feed salts quickly — water until it drains each time and flush the pot with plain water every few weeks, especially on a sunny windowsill.
Keep reading
- Garden Catmint care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water garden 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 barbecue rosemary
- How to fertilise rose-scented geranium
- How to fertilise coconut-scented geranium
- All 6887 fertilising guides in the Growli library