Repotting guide

When & how to repot Lamb's Stomatium (Stomatium agninum)

Also called Lamb's Mesemb, Stomatium.

More about lamb's stomatium

About Lamb's Stomatium

Stomatium agninum · also called Lamb's Mesemb, Stomatium · houseplant

Stomatium agninum is a night-flowering Aizoaceae succulent from South Africa, forming low clusters of grey-green, rough-textured leaves. Its sweetly scented yellow flowers open in the evening, making it a delightful windowsill oddity. It needs excellent drainage and a dry winter rest. Not ASPCA-listed; treat cautiously around pets.

Mature size: 5-8 cm tall, spreading to 20 cm in clusters

Watch for — Root rot: Overwatering or waterlogged soil is the main cause of failure. Allow complete drying between waterings.

How to tell lamb's stomatium needs repotting

Repotting on a calendar is less reliable than reading the plant. For lamb's stomatium, 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 lamb's stomatium

Every 2–3 years, into bone-dry mix. Lamb's Stomatium's growth habit — low, clump-forming succulent with rough-textured leaves — sets the pace. Stomatium agninum is a night-flowering Aizoaceae succulent from South Africa, forming low clusters of grey-green, rough-textured leaves. Its sweetly scented yellow flowers open in the evening, making it a delightful windowsill oddity. It needs excellent drainage and a dry winter rest. Not ASPCA-listed; treat cautiously around pets.

What size pot to step lamb's stomatium up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Lamb's Stomatium 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 lamb's stomatium

Spring or summer, while lamb's stomatium 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 lamb's stomatium

Repot dry. Do not water lamb's stomatium 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 free-draining cactus or succulent mix with added coarse grit 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 lamb's stomatium 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 lamb's stomatium 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 lamb's stomatium

Lamb's Stomatium wants free-draining cactus or succulent mix with added coarse grit. Use 50-60% cactus compost and 40-50% coarse grit or perlite. Terracotta pots help maintain the drier conditions this plant prefers. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting lamb's stomatium — frequently asked questions

How often should you repot lamb's stomatium?

Every 2–3 years, into bone-dry mix for lamb's stomatium. Repot lamb's stomatium every 2–3 years into a snug pot of free-draining cactus or succulent mix with added coarse grit, 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 lamb's stomatium need?

When is the best time of year to repot lamb's stomatium?

Should you water lamb's stomatium after repotting?

No — not straight away. Repot lamb's stomatium 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 lamb's stomatium after repotting?

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