Moth orchid: lower leaves turning yellow

What it is likely to be on moth orchid

1. Normal leaf ageing

   May be normalcommon on this plant

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Houseplant problems

   Checked 2026-08-13

   Not a problem, and included as a candidate because it is one of the commonest explanations for a single yellow leaf on an otherwise healthy plant. Every plant sheds its oldest leaves; a differential that cannot return 'nothing is wrong' will always find something to blame.

   Points towards it

   • · only the lowest, oldest leaf is involved and the rest of the plant looks well
   • · one leaf at a time, not a general decline
   • · nothing changed, which is what you would expect of an ordinary process

   Argues against it

   • · several leaves yellowing at once across the plant is not ageing — ageing takes one leaf at a time from the bottom — this rules it out entirely.

   Check this next

   Count how many leaves are affected and where they are. One lowest leaf yellowing on a plant that is otherwise growing well is what these plants do; three or more at once, or any yellowing higher up, is a problem.

   What to do now

   Remove the leaf when it comes away easily and change nothing else. This is the diagnosis most worth getting right on a houseplant, because the usual response — watering much less on suspicion of root rot — damages a plant that was perfectly healthy.

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Houseplant problems

   Checked 2026-08-13

2. Overwatering

   Candidate 2very common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Overwatering

   Checked 2026-08-13

   Not a matter of volume but of frequency: roots need air as well as water, and compost that never dries suffocates them. It kills more houseplants than every pest and disease combined, and its cruellest feature is that the early signs — yellowing, wilting, dropping leaves — look exactly like drought, so the instinct is to water more.

   Points towards it

   • · the compost is wet and the plant is yellowing anyway
   • · saucers and cachepots left full are the commonest cause
   • · roots short of air affect the whole plant rather than one old leaf

   Argues against it

   • · the compost is dry, so the roots are not short of air — this rules it out entirely.
   • · a single lowest leaf yellowing on an otherwise healthy plant is ordinary ageing rather than waterlogging

   Check this next

   Count the yellow leaves and feel the compost at depth. One lowest leaf on a plant that is otherwise growing well is normal ageing; several at once with wet compost is waterlogging, and the next step is to tip the plant out and look at the roots rather than to feed it.

   What to do now

   Empty the saucer or cachepot and stop watering until the top few centimetres are dry. Do not feed a yellowing plant in wet compost — the roots cannot take up what is already there, and feeding adds salts to a root system that is already struggling.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Overwatering — recovery

   Checked 2026-08-13

Narrow it down

This page lists everything at once, which is the right shape for reading and the wrong shape for deciding. The interactive tool asks one question at a time, starting with whichever would separate these causes fastest, and stops as soon as further answers would not help.

Opens with the plant and the symptom already set. Nothing you answer is stored or sent anywhere — the answers live in the address bar and nowhere else.

What this does not cover

These are the causes GrowingHQ holds rules for on moth orchid — not every cause there is. Where several problems look alike, the honest answer is often that they cannot be told apart by eye, and a page that named one would be guessing. If none of the above fits, the general lower leaves turning yellow page lists causes across all plants, and the Moth orchid profile lists the problems it is prone to.