Nitrogen Deficiency
TreatableNutrient problem · does not spread
Nitrogen is mobile inside a plant, so when it runs short the plant strips it out of old leaves to feed new ones. That is why nitrogen shortage always shows at the bottom first and why the yellowing is even rather than patterned. It is one of the easiest problems to fix and one of the most commonly misdiagnosed as disease.
What it looks like
Uniform pale yellowing of the whole leaf, including the veins, starting with the oldest lowest leaves and working upward. Growth is slow and the plant looks generally thin and pale.
How to confirm it
- Whole leaf yellows evenly, veins included.
- Starts on the oldest lowest leaves — a mobile-nutrient signature.
- No spots, fuzz, holes or insects.
- Growth visibly slow and stems thin.
What to do
- 1Feed with a balanced or nitrogen-rich fertiliser. Response is usually visible within one to two weeks.
- 2A liquid feed acts fastest if the plant is fruiting and time matters.
- 3Check that the plant is not simply pot-bound and out of soil to draw from.
What it gets confused with
One observation settles each of these.
Iron shortage yellows the tissue between the veins while the veins stay green, and it hits the newest leaves first.
Overwatered plants yellow with wet soil and often wilt at the same time. Check the soil before feeding.
Preventing it next time
- Work compost into beds before planting.
- Feed containers regularly — nitrogen leaches out of pots with every watering.
- Be careful with fresh wood chips dug into soil, which tie up nitrogen as they break down.
Plants affected
Most garden and container plants can be affected.
Check these two things first
- Push a finger into the soil, two knuckles deep. Wet soil plus a wilting plant means too much water, not too little — and it is the commonest reason a plant is dying. Dry soil plus crisp leaves means the opposite. The leaves look nearly identical either way, so the soil is what tells you.
- Turn a damaged leaf over. Half of all diagnoses live on the underside: fuzz means downy mildew, fine webbing means spider mites, clusters of insects mean aphids. Nothing on the top of a leaf is as informative.
Most garden problems are cosmetic and resolve without treatment. Reach for a spray last, not first.