Burro's tail soft or mushy stem: causes and what to do
5 results in the diagnosis tree begin with a soft, mushy stem, 3 of them marked likely when the answers fit. They are ordered here for Burro's tail (Sedum morganianum), using what its sources say about soil moisture, soil, cold tolerance and watering and 2 problems recorded for it.
Sources last read 14 September 2026.
Sedum morganianum, the donkey tail or burro's tail, is a species of flowering plant in the family Crassulaceae, native to southern Mexico. It is a succulent perennial producing trailing stems up to 60 cm (24 in) long, with fleshy blue-green leaves and terminal pink to red flowers in summer. Wikipedia, CC BY-SA 4.0
Native range: Mexico (Veracruz, Puebla, Chiapas) (seasonally dry tropical). Also sold as donkey tail, donkey's tail, horse's tail, lamb's tail and Stonecrop.
What Burro's tail’s sources say that bears on this
- Soil moisture
- Well-drainedRHS · read 13 September 2026
- Soil
- Loam, Sand, Chalk; pH Alkaline or NeutralRHS · read 13 September 2026
- Cold tolerance
- H1C — 5–10°CRHS · read 13 September 2026
- Watering
- Use lukewarm water, and water less in winter. Let the soil dry between waterings, and feed lightly once or twice in the growing season.NC State Extension · read 13 September 2026In the growing season, water generously and feed monthly with a liquid fertiliser at half strength; give little water in winter.RHS · read 13 September 2026
How this shows up on a Burro's tail
Leaves soften and curl inward
Leaves on the Burro's tail turn dull and soft before any colour changes, and water poured on the dry surface runs straight down the inside of the pot.
Its source describes well-drained soil. Below that the cells lose pressure, and pressure is what holds a leaf out straight.
Telling it apart: The weight of the pot. Light and sagging is thirst; heavy and sagging is not.
RHS · read 13 September 2026Swollen, darkening leaves that come away at a touch
Soft, discoloured tissue appears where the leaves join the stem of the Burro's tail, and the compost smells stale rather than earthy.
A plant that stores its own water has little use for more. Kept in well-drained soil that stays wet, the stored tissue takes up water it cannot release and the cell walls give way.
Telling it apart: Firm and wrinkled is thirst; soft and swollen is the opposite. The two look similar from across a room and feel nothing alike.
RHS · read 13 September 2026Possible causes, likeliest first for a Burro's tail
Most likely too much water for a plant that stores its own
Ranked higher because Burro's tail's recorded problems point this way.
Burro's tail stores water in its own tissue, which makes it more sensitive to wet soil than most leafy plants, so this reading is stronger for it.
- Well-drained RHS · read 13 September 2026
- Loam, Sand, Chalk; pH Alkaline or Neutral RHS · read 13 September 2026
Why: A burro's tail built to survive drought has little use for extra water.
What to try:
- Stop watering and let the compost dry right through.
- Remove soft leaves, and check the base of the stem for rot.
What would settle it: Press a leaf gently. A thirsty succulent leaf is wrinkled and springs back; a waterlogged one is swollen and stays dented.
Most likely rot at the base of the stem
- Well-drained RHS · read 13 September 2026
- Loam, Sand, Chalk; pH Alkaline or Neutral RHS · read 13 September 2026
Why: A stem that is soft or dark at the soil line, in wet compost, has usually been invaded by the fungi and bacteria that thrive where roots and stems sit wet.
What to try:
- Look for any firm, healthy stems or tips above the damage; cuttings from those may root even if the base cannot be saved.
- Throw away the affected compost rather than reusing it, and wash the pot before using it again.
What would settle it: Cut a small slice from the affected stem. Discoloured tissue running up inside it is rot; a clean pale centre means the damage is on the surface.
Most likely cold
- H1C — 5–10°C RHS · read 13 September 2026
Why: Soft, dark patches rather than crisp ones are damaged tissue rather than dried tissue.
What to try:
- Move it away from the glass at night, or keep the curtain on the room side of the burro's tail.
- Leave damaged leaves until new growth appears, then remove the worst of them.
What would settle it: Where the burro's tail sits at night, and what the glass feels like at that hour. Damage that appeared after one cold night, on the side facing the window, is the pattern.
Less likely for a Burro's tail, still possible
Questions
- What usually causes a soft, mushy stem on a Burro's tail?
- For Burro's tail: most likely too much water for a plant that stores its own, most likely rot at the base of the stem and most likely cold. Burro's tail stores water in its own tissue, which makes it more sensitive to wet soil than most leafy plants, so this reading is stronger for it.
- How can I tell which one it is on my Burro's tail?
- Where is it soft? At the soil line: the stem is dark and gives when pressed; Leaves low on the plant are swollen, soft and slightly see-through; Dark, soft patches higher up the plant.
- What do Burro's tail's sources say about its soil moisture?
- RHS: Well-drained.
- What does this look like on a Burro's tail?
- Leaves on the Burro's tail turn dull and soft before any colour changes, and water poured on the dry surface runs straight down the inside of the pot. Telling it apart: The weight of the pot. Light and sagging is thirst; heavy and sagging is not.
Other plants that show a soft, mushy stem
Jade plantSwollen, darkening leaves that come away at a touch
Mexican snowballSwollen, darkening leaves that come away at a touch
Aloe veraMushy tissue at the base of the aloe vera
Baby rubber plantLeaves turn glassy from the stem outward
Bunny ears cactusLeaves go soft and slightly see-through
Cast iron plantSoft, sagging blades low on the clump in soil that has not dried
Something else wrong with the Burro's tail?
What this does not cover
This page orders a decision tree's results using a plant's sourced care. It has not seen your plant, its pot or its window, and two problems at once are common: that is the usual reason a confident answer turns out wrong. The questions in the diagnosis tool narrow it further than a list can.