Nutrient deficiency
Pale or yellowing leaves and weak growth when the plant runs short of food.
What you'll see
- Nitrogen: older, lower leaves turn evenly pale yellow first, and growth is slow.
- Iron: the newest leaves turn yellow between the veins while the veins stay green.
- Magnesium: older leaves yellow between the veins, sometimes with reddish tints.
- Overall: weak growth, small leaves and few flowers, especially in pots left unfed for months.
Why it happens
Potting mix runs out of nutrients over time, and alkaline, cold, dry or soggy soil can stop roots from taking them up.
How to fix it
- Rule out watering and root problems first; damaged roots can't take up food.
- Feed with a balanced fertilizer at the strength on the label or weaker while the plant is growing.
- For iron yellowing, use a chelated iron product as the label says, and lower the soil pH for acid lovers.
Keep it from coming back
- Repot long-kept plants into fresh mix every few years.
- Feed lightly and regularly in spring and summer, not during the winter rest.
- Test garden soil pH before adding iron.
Read more
- N-P-K: fertilizer numbers explained
- How to fertilize houseplants
- Fertilizer types compared
- Hydroponics at home: the basics
Sources
- Kindwise plant.health library: Nutrient deficiency
- RHS: Nutrient deficiencies
- Missouri Botanical Garden: Nutrient deficiencies
- University of Maryland Extension: Nutrient deficiency of indoor plants
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.