Repotting guide

When & how to repot Alpine Mouse-ear (Cerastium alpinum)

Also called Alpine Mouse-ear, Alpine Chickweed.

More about alpine mouse-ear

About Alpine Mouse-ear

Cerastium alpinum · also called Alpine Mouse-ear, Alpine Chickweed · flowering

A delicate, cushion-forming perennial native to Arctic and alpine zones across the Northern Hemisphere, including mountain ranges of Europe and North America. Produces small, pristine white flowers with notched petals above a compact mat of hairy, grey-green leaves in late spring. Best suited to troughs, alpine houses, or specialist rock gardens requiring excellent drainage.

Mature size: 5–10 cm tall, 15–25 cm wide

How to tell alpine mouse-ear needs repotting

Repotting on a calendar is less reliable than reading the plant. For alpine mouse-ear, 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 alpine mouse-ear

Every 2–3 years, into bone-dry mix. Alpine Mouse-ear's growth habit — compact, cushion- to mat-forming perennial — sets the pace. A delicate, cushion-forming perennial native to Arctic and alpine zones across the Northern Hemisphere, including mountain ranges of Europe and North America. Produces small, pristine white flowers with notched petals above a compact mat of hairy, grey-green leaves in late spring. Best suited to troughs, alpine houses, or specialist rock gardens requiring excellent drainage.

What size pot to step alpine mouse-ear up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Alpine Mouse-ear 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 alpine mouse-ear

Spring or summer, while alpine mouse-ear 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 alpine mouse-ear

Repot dry. Do not water alpine mouse-ear 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 extremely well-drained, lean, gritty alpine mix 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 alpine mouse-ear 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 alpine mouse-ear 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 alpine mouse-ear

Alpine Mouse-ear wants extremely well-drained, lean, gritty alpine mix. Use a 50:50 blend of loam and coarse horticultural grit, or a purpose-made alpine compost. Fertility should be low. Acidic to neutral pH (5.5–7.0) is appropriate — unlike the related C. tomentosum, it is native to siliceous as well as calcareous substrates. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting alpine mouse-ear — frequently asked questions

How often should you repot alpine mouse-ear?

Every 2–3 years, into bone-dry mix for alpine mouse-ear. Repot alpine mouse-ear every 2–3 years into a snug pot of extremely well-drained, lean, gritty alpine mix, 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 alpine mouse-ear need?

When is the best time of year to repot alpine mouse-ear?

Should you water alpine mouse-ear after repotting?

No — not straight away. Repot alpine mouse-ear 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 alpine mouse-ear after repotting?

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