Flaming Katy leaves turning yellow: causes and what to do
17 results in the diagnosis tree begin with yellowing leaves, 7 of them marked likely when the answers fit. They are ordered here for Flaming Katy (Kalanchoe blossfeldiana), using what its sources say about soil moisture, light, soil, watering and feeding and one problem recorded for it.
Sources last read 14 September 2026.
Kalanchoe blossfeldiana is a commonly cultivated evergreen house plant of the genus Kalanchoe native to Madagascar. It is known by the English common names flaming Katy, Christmas kalanchoe, florist kalanchoe and Madagascar widow's-thrill. Wikipedia, CC BY-SA 4.0
Native range: NE. Madagascar (seasonally dry tropical). Also sold as Christmas Kalanchoe, Florist Kalanchoe, Madagascar Widow's Thrill and panda plant.
What Flaming Katy’s sources say that bears on this
- Soil moisture
- Moist but well-drained or Well-drainedRHS · read 13 September 2026
- Light
- Partial shadeRHS · read 13 September 2026
- Soil
- Loam, Sand; pH Acid or Alkaline or NeutralRHS · read 13 September 2026
- Watering
- They are drought tolerant; let the soil dry out, then water deeply.NC State Extension · read 13 September 2026During growth water moderately; while dormant water sparingly.RHS · read 13 September 2026
- Feeding
- Give a balanced liquid fertiliser two or three times during the growing season.RHS · read 13 September 2026
How this shows up on a Flaming Katy
Lower leaves collapse and yellow within days of a watering
A sour smell from the compost is common on a flaming Katy, and the lowest leaves on each stem come away when pulled. The surface may look dry while everything beneath it is not.
The source for this plant describes moist but well-drained or well-drained soil. Compost that stays saturated loses the air spaces fine roots grow into, and those roots die back first.
Telling it apart: Weigh the pot in your hand. A pot still heavy a week after watering is holding more water than the roots are using.
RHS · read 13 September 2026Possible causes, likeliest first for a Flaming Katy
Most likely too little water
Ranked higher because Flaming Katy's recorded problems point this way.
- Moist but well-drained or Well-drained RHS · read 13 September 2026
Why: Soil dry two inches down, under lower leaves that are yellowing or leaves that are falling, is a flaming katy shedding what it cannot support.
What to try:
- Water until it runs from the drainage hole, then let the pot drain.Useful: pot with drainage holes
- If the water runs straight through a shrunken rootball, stand the pot in water for twenty minutes so the compost can take it up.
What would settle it: Water it thoroughly and look again the same evening. A thirsty plant firms up fast. One that does not has a root problem rather than a water problem.
Most likely too little water
Ranked higher because Flaming Katy's recorded problems point this way.
- Moist but well-drained or Well-drained RHS · read 13 September 2026
Why: Soil dry two inches down leaves the roots nothing to send up, and the leaf edges are the last tissue in line.
What to try:
- Water thoroughly, until it runs from the drainage hole.Useful: pot with drainage holes
- Check the soil with a finger every few days rather than watering on a fixed day.Useful: moisture meter
What would settle it: Water it thoroughly and watch the next new leaves. If they come in with clean edges under steadier watering, the edges were thirst.
Most likely cold
Ranked higher for Flaming Katy because of what its sources say.
Its RHS hardiness rating puts this plant's cold floor at 10°C or above, so a cold windowsill at night is a strong explanation.
- H1B — 10–15°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 flaming katy.
- Leave damaged leaves until new growth appears, then remove the worst of them.
What would settle it: Where the flaming katy 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 Flaming Katy, still possible
- Most likely not enough light
- Most likely short of nutrients
- Most likely too much water
- Most likely a build-up of salts in the soil
- Nutrients are an unlikely explanation here
- Possibly root rot, in a pot that has stopped draining
- Possibly too much direct sun
- Possibly too much direct sun, or feeding
- This may be ordinary leaf loss
- Light and feeding are both plausible, and this does not separate them
- Probably too much water, but this is not settled
- Possibly dry air
- Probably too much water
- The answers do not point at one cause
Questions
- What usually causes yellowing leaves on a Flaming Katy?
- For Flaming Katy: most likely too little water, most likely too little water and most likely cold.
- How can I tell which one it is on my Flaming Katy?
- Where is the yellowing? The lowest leaves, working upward; New growth at the top, while older leaves stay green; Between the veins, the veins themselves still green; At the leaf tips and edges, browning as it goes; Patchy, only on the side facing the window.
- What do Flaming Katy's sources say about its soil moisture?
- RHS: Moist but well-drained or Well-drained.
- What does this look like on a Flaming Katy?
- A sour smell from the compost is common on a flaming Katy, and the lowest leaves on each stem come away when pulled. The surface may look dry while everything beneath it is not. Telling it apart: Weigh the pot in your hand. A pot still heavy a week after watering is holding more water than the roots are using.
- Is Flaming Katy safe to handle while I check it?
- Its sources list it as toxic to cats and dogs. Wash your hands after handling the roots or sap, and keep trimmings away from pets.
Other plants that show yellowing leaves
African violetLower leaves collapse and yellow within days of a watering
Barberton daisyWrinkling rather than yellowing
Bearded irisFaded, yellow-white areas on the sunny side of the plant
Bigleaf hydrangeaPale dry areas across the upper leaves only
Bird of paradiseFaded, yellow-white areas on the sunny side of the plant
Bush lilyPale dry areas across the upper leaves only
Something else wrong with the Flaming Katy?
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.