Repotting guide

When & how to repot Euphorbia piscidermis (Euphorbia piscidermis)

Also called fish-skin euphorbia.

More about euphorbia piscidermis

About Euphorbia piscidermis

Euphorbia piscidermis · also called fish-skin euphorbia · houseplant

Euphorbia piscidermis is a prized, slow Ethiopian succulent named for its fish-scale-patterned globular body of overlapping tubercles. A demanding collector's plant, it needs intense light, an extremely gritty mix and a cautious hand with water; it rots at the slightest excess. The latex is irritant, so handle with gloves. Reward for patience is a remarkably sculptural miniature.

Mature size: Typically just 3-6 cm in diameter; a true miniature that rarely exceeds a few centimetres tall.

Watch for — Weak roots: The species struggles on its own roots, which is why it is often grafted. If ungrafted, keep drainage extreme and watering very light.

How to tell euphorbia piscidermis needs repotting

Repotting on a calendar is less reliable than reading the plant. For euphorbia piscidermis, 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 euphorbia piscidermis

Every 2–3 years, into bone-dry mix. Euphorbia piscidermis's growth habit — dwarf globular succulent forming a single rounded body covered in overlapping, scale-like tubercles; remains small and grows extremely slowly, occasionally offsetting. — sets the pace. Euphorbia piscidermis is a prized, slow Ethiopian succulent named for its fish-scale-patterned globular body of overlapping tubercles. A demanding collector's plant, it needs intense light, an extremely gritty mix and a cautious hand with water; it rots at the slightest excess. The latex is irritant, so handle with gloves. Reward for patience is a remarkably sculptural miniature.

What size pot to step euphorbia piscidermis up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Euphorbia piscidermis 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 euphorbia piscidermis

Spring or summer, while euphorbia piscidermis 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 euphorbia piscidermis

Repot dry. Do not water euphorbia piscidermis 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 gritty mineral 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 euphorbia piscidermis 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 euphorbia piscidermis 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 euphorbia piscidermis

Euphorbia piscidermis wants extremely gritty mineral mix. Use a predominantly mineral medium, mostly pumice, lava grit or perlite with only a little organic matter, so water passes straight through. Often grown grafted to ease its difficult roots. A small clay pot is best. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting euphorbia piscidermis — frequently asked questions

How often should you repot euphorbia piscidermis?

Every 2–3 years, into bone-dry mix for euphorbia piscidermis. Repot euphorbia piscidermis every 2–3 years into a snug pot of extremely gritty mineral 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 euphorbia piscidermis need?

When is the best time of year to repot euphorbia piscidermis?

Should you water euphorbia piscidermis after repotting?

No — not straight away. Repot euphorbia piscidermis 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 euphorbia piscidermis after repotting?

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