Yellow leaves can follow heavy or persistently wet soil and root damage, underwatering or prolonged dryness, insufficient indoor light, cold or winter injury and pest pressure. Outdoor and indoor context can change which check comes first.
Why Rosmarinus officinalis has yellow leaves
Rosemary yellowing is an observation, not a single cause. Rosmarinus officinalis is the former name for Salvia rosmarinus. A sunny herb bed and an indoor winter pot need different checks.
Plant coveredRosmarinus officinalisRosemary · indoor and outdoor
Check the leaves, stems and pot
Which leaves are yellow?
Record whether yellowing affects older lower leaves or new growth, whether foliage is also dry or brown and whether leaves are dropping, spotted or attached to stems that are soft or declining. Color alone does not identify the cause.
Check how wet the medium stays, whether the pot drains freely, the light level, recent movement indoors, cold or warm drafts, root condition, feeding history and the undersides of leaves for mites or other pests.
Use the visible signs to choose the next check
Possible causes and next checks
Start with the root-zone check: if the medium stays wet, improve drainage and withhold routine watering until normal dry-down. Indoors, review light and temperature before adding fertilizer, and inspect for pests when stippling or webbing is present.
Watch for new damage or recovery
What to watch next
After changing one condition, watch new growth, ongoing leaf drop, the moisture trend and any spreading spots. If stems continue to decline or roots remain compromised, reassess the indoor or outdoor context instead of repeating fertilizer. No fixed interval is supplied.
Do not diagnose from one sign alone
What yellow leaves cannot tell you
Sources
- Royal Botanic Gardens, Kew: Plants of the World OnlineTaxonomy; synonym relationship
- Royal Botanic Gardens, Kew: Plants of the World OnlineTaxonomy; accepted name; synonyms
- Royal Horticultural SocietyPlanting; watering; winter protection; pests and diseases
- University of Maryland Extension Ask ExtensionRosemary bucket brought indoors; watering, drainage, fertilizer and dead material
- Ask Extension university horticulture networkYellowing Rosemary Plants; drainage and wet-soil response
- Iowa State University Extension and OutreachHerbs indoors; rosemary; light, watering, drainage and pests
- Missouri Botanical GardenHerb problems indoors; wet soil; insufficient light; rosemary