Yellow leaves on your Anthurium have a few possible causes, and on this plant the likeliest is overwatering and early root rot. Check the causes below to find which one fits, then follow its fix.
Overwatering & early root rot. Stop watering. Make sure the pot can actually drain, and wait until the top 3 cm (1.2 in) of soil feel dry. If the base is mushy or smells sour, unpot it and trim any brown, soft roots before repotting in fresh mix. Wear gloves before cutting or dividing. Sap or foliage can irritate skin. Avoid contact with eyes and mouth, and wash your hands after handling. Keep cut pieces out of reach of children and pets.
Other possible causes
Not a match? Compare the signs below to find the one you have.
Thirst (underwatering)
How to tell
The soil is bone dry, and the yellowing arrives alongside crispy leaf edges rather than soft, mushy growth.
The fix
If the soil is dry, water thoroughly (every 6 to 8 days in summer is the usual pace for an Anthurium), then settle into feeling the soil before every watering rather than watering on a fixed day.
Too little light
How to tell
The yellowing comes with pale, stretched new growth leaning toward the nearest window. That combination shows that the spot is too dim for an Anthurium.
The fix
Move it to a brighter spot, but keep it out of harsh midday sun, which scorches.
Hungry (nutrient shortfall)
How to tell
Older leaves fade to an even pale yellow and growth has clearly slowed, usually after many months in the same tired mix.
The fix
Feed with a balanced, diluted liquid fertilizer through the growing season, and refresh the top layer or repot if it’s been over a year.
Simple old age
How to tell
A single bottom leaf slowly yellows while the rest of the plant looks healthy and is pushing new growth.
The fix
Nothing is wrong. Snip the spent leaf off and carry on. Plants retire their oldest leaves.
Thrips
How to tell
Silvery patches with tiny black dots point to thrips.
The fix
Rinse the plant, cut off the worst leaves and treat in rounds, as the thrips guide explains.