Soil & potting mix
Best soil for Cat Thyme (Teucrium marum)
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.
Preferred mix: Well-drained chalk, loam, or sand; neutral to alkaline pH
Watch for — Root rot from winter wet: The most frequent killer; ensure the planting site has near-perfect drainage and consider a grit mulch around the collar to divert standing water.
Why cat thyme needs this mix
Cat Thyme is a Mediterranean dry-hillside plant — it wants a lean, sharply drained, slightly alkaline mix, and rots fast in rich, water-holding soil.
- Cat Thyme evolved on stony, sun-baked slopes — its roots expect to dry out hard and quickly between rains, so the mix must drain almost as fast as you pour.
- A lean, low-nutrient mix keeps growth firm and aromatic; a rich one gives soft, sappy, flavourless growth that flops and rots.
- It tolerates and often prefers a slightly alkaline soil, the opposite of most houseplants.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons cat thyme struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- Rich, moisture-holding compost is the classic killer of cat thyme — especially over a cold, wet winter, when the base of the plant simply rots.
- A peaty, acidic potting mix is doubly wrong: too wet and the wrong pH direction.
- No grit means the rootball stays damp for days, which a dry-climate root system never copes with.
Growing cat thyme in ordinary rich, moisture-retentive compost. Lean it out with at least a third grit, and never let it sit wet over winter.
pH — does it matter for cat thyme?
Cat Thyme likes neutral to slightly alkaline soil, roughly pH 6.5-7.5. If your soil or compost is acidic, a little garden lime or extra grit nudges it the right way — the one common plant where you may add lime.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
Bagged "herb" or "Mediterranean" mixes are usually fine for cat thyme, but most standard composts need cutting hard with grit. The DIY ratio above is cheap and exactly right.
Drainage and the pot
Sharp drainage is everything: a terracotta pot with a big hole, gritty mix and never a saucer left full. Raised beds suit these herbs outdoors for the same reason.
A gritty mix barely breaks down, so cat thyme needs little repotting — refresh the top layer and the grit every couple of years rather than potting on aggressively. When the time comes, our repotting guide for cat thyme covers the timing and technique step by step.
Cat Thyme soil — frequently asked questions
What is the best soil mix for cat thyme?
2 parts standard peat-free compost or loam : 1 part coarse horticultural grit : 1 part perlite or coarse sand. Cat Thyme evolved on stony, sun-baked slopes — its roots expect to dry out hard and quickly between rains, so the mix must drain almost as fast as you pour.
Can I use normal potting soil for cat thyme?
Rich, moisture-holding compost is the classic killer of cat thyme — especially over a cold, wet winter, when the base of the plant simply rots. Bagged "herb" or "Mediterranean" mixes are usually fine for cat thyme, but most standard composts need cutting hard with grit. The DIY ratio above is cheap and exactly right.
Does cat thyme need a special pH?
Cat Thyme likes neutral to slightly alkaline soil, roughly pH 6.5-7.5. If your soil or compost is acidic, a little garden lime or extra grit nudges it the right way — the one common plant where you may add lime.
Should I buy a bagged mix or make my own for cat thyme?
Bagged "herb" or "Mediterranean" mixes are usually fine for cat thyme, but most standard composts need cutting hard with grit. The DIY ratio above is cheap and exactly right.
How often should I refresh the soil for cat thyme?
A gritty mix barely breaks down, so cat thyme needs little repotting — refresh the top layer and the grit every couple of years rather than potting on aggressively. Sharp drainage is everything: a terracotta pot with a big hole, gritty mix and never a saucer left full. Raised beds suit these herbs outdoors for the same reason.
Keep reading
- Cat Thyme care — the full brief (light, water, humidity, problems, pet safety)
- How often to water cat thyme — the schedule the mix feeds into
- Repotting cat thyme — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Overwatered plant — signs and recovery
- Root rot — how the wrong soil starts it, and how to save the plant
- Should I water my plant? The simple check first
- Best soil for wild thyme
- Best soil for jurisic's sage
- Best soil for spanish sage
- All 10153 soil and potting-mix guides in the Growli library