Repotting guide

When & how to repot Mountain Lemon Thyme (Thymus nervosus)

Also called Mountain lemon thyme, Pyrenean thyme.

More about mountain lemon thyme

About Mountain Lemon Thyme

Thymus nervosus · also called Mountain lemon thyme, Pyrenean thyme · herb

Thymus nervosus is an aromatic, compact sub-shrub native to mountain grasslands and rocky slopes of the Pyrenees and Cantabrian Mountains, typically at subalpine elevations. It produces small, bright pink-purple flowers in summer and carries a distinctly lemony fragrance similar to Thymus citriodorus, making it attractive for both alpine planting and herb gardens. Like all thymes, sharp drainage and a sunny, open position are essential — winter wet is far more damaging than cold. The ASPCA classifies thyme as non-toxic to cats, dogs, and horses.

Mature size: 10–15 cm tall, 25–40 cm spread.

How to tell mountain lemon thyme needs repotting

Repotting on a calendar is less reliable than reading the plant. For mountain lemon thyme, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot mountain lemon thyme

Every 2–3 years, into bone-dry mix. Mountain Lemon Thyme's growth habit — compact, mound-forming evergreen sub-shrub with slender, slightly woody stems. — sets the pace. Thymus nervosus is an aromatic, compact sub-shrub native to mountain grasslands and rocky slopes of the Pyrenees and Cantabrian Mountains, typically at subalpine elevations. It produces small, bright pink-purple flowers in summer and carries a distinctly lemony fragrance similar to Thymus citriodorus, making it attractive for both alpine planting and herb gardens. Like all thymes, sharp drainage and a sunny, open position are essential — winter wet is far more damaging than cold. The ASPCA classifies thyme as non-toxic to cats, dogs, and horses.

What size pot to step mountain lemon thyme up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Mountain Lemon Thyme stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot mountain lemon thyme

Spring or summer, while mountain lemon thyme is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting mountain lemon thyme

Repot dry. Do not water mountain lemon thyme for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty sharply drained, gritty, alkaline to neutral soil ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set mountain lemon thyme at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep mountain lemon thyme completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for mountain lemon thyme

Mountain Lemon Thyme wants sharply drained, gritty, alkaline to neutral soil. Incorporate generous horticultural grit or gravel; a 5 cm grit mulch around the collar of the plant is recommended in high-rainfall sites to keep the crown dry. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting mountain lemon thyme — frequently asked questions

How often should you repot mountain lemon thyme?

Every 2–3 years, into bone-dry mix for mountain lemon thyme. Repot mountain lemon thyme every 2–3 years into a snug pot of sharply drained, gritty, alkaline to neutral soil, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does mountain lemon thyme need?

When is the best time of year to repot mountain lemon thyme?

Should you water mountain lemon thyme after repotting?

No — not straight away. Repot mountain lemon thyme into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise mountain lemon thyme after repotting?

Not immediately. Wait about 3 weeks after repotting mountain lemon thyme. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.