Fertilising guide

How to fertilise Cat Thyme (Teucrium marum)— schedule & NPK

Also called Cat Thyme, Kitty Crack, Mediterranean Germander, Cat Crack.

More about cat thyme

About Cat Thyme

Teucrium marum · also called Cat Thyme, Kitty Crack · herb

Teucrium marum is a compact, evergreen subshrub native to the western Mediterranean, particularly Sardinia and the Balearic Islands. It produces grey-green, downy, aromatic foliage and small pink flowers on slender spikes in late summer and autumn. Full sun and sharply drained, alkaline soil are essential — winter wet is more damaging than frost. The plant is mildly toxic if ingested; the RHS advises wearing gloves when handling, though it is famous for attracting cats with a catnip-like effect.

Growth habit: Compact, bushy evergreen subshrub with a mounded form.

What fertiliser cat thyme actually wants — and why

Cat Thyme is a lean, aromatic herb — the essential-oil flavour you grow it for is strongest in poor soil, so feeding it actively makes it worse.

Little or nothing. If anything, a very weak balanced feed or a thin compost top-dress — never a rich nitrogen feed, which dilutes the aromatic oils and produces soft, bland, floppy growth.

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 cat thyme: 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 cat thyme, 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 cat thyme:

Apply a balanced, low-nitrogen feed once in spring; excess feeding produces lush, weak growth prone to winter damage. In practice: a spring compost top-dress at most, and otherwise leave cat thyme unfed — lean, sharp-draining soil is exactly what concentrates its flavour.

The dormant-season rule matters more than the exact interval: skip feeding entirely when cat thyme 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 cat thyme

As weak as it gets for cat thyme, or none at all. The flavour-versus-growth trade-off runs the opposite way to leafy crops: restraint is the technique.

Feeding always goes onto already-damp soil, never dry roots — water cat thyme first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the cat thyme watering schedule.

Signs you are over-feeding cat thyme

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for cat thyme:

Lush, soft, fast growth with noticeably weaker scent and flavour.
Floppy stems, sparse essential oils, and poor cold/wet hardiness.
Salt crust in containers and scorched leaf tips from over-feeding.

Signs you are under-feeding cat thyme

Rare — these herbs thrive on lean soil.
Only on truly exhausted soil: pale, thin, very slow growth.
A short-lived, weak plant in a long-spent container.

If the symptoms point at watering, light or roots rather than nutrition, the full cat thyme care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Over-feeding is so unlikely with cat thyme that flushing is rarely needed; if a container has had feed, a single plain-water flush and a switch to a leaner, grittier mix resets it.

Organic vs synthetic feeds for cat thyme

Organic options

A thin spring mulch of garden compost or leaf-mould is the most these want. UK: a little garden compost; US: a light Espoma Garden-tone top-dress at most. Lean and gritty beats fed and rich every time.

Synthetic / liquid feeds

Generally none for cat thyme. At absolute most, a very dilute balanced feed once or twice in a container; in the ground, nothing — synthetic feeds work directly against the flavour.

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 cat thyme — frequently asked questions

What fertiliser does cat thyme need?

Little or nothing. If anything, a very weak balanced feed or a thin compost top-dress — never a rich nitrogen feed, which dilutes the aromatic oils and produces soft, bland, floppy growth. Cat Thyme is a lean, aromatic herb — the essential-oil flavour you grow it for is strongest in poor soil, so feeding it actively makes it worse.

How often should I feed cat thyme?

Apply a balanced, low-nitrogen feed once in spring; excess feeding produces lush, weak growth prone to winter damage. Apply a balanced, low-nitrogen feed once in spring; excess feeding produces lush, weak growth prone to winter damage. In practice: a spring compost top-dress at most, and otherwise leave cat thyme unfed — lean, sharp-draining soil is exactly what concentrates its flavour.

What strength of feed for cat thyme?