9 min readStart with one question: are the old leaves yellowing, or the new ones? Nutrients that move inside the plant, including nitrogen, magnesium and potassium, cause symptoms on old leaves first. Nutrients that cannot move, including iron, zinc and calcium, show on new growth first. That single split narrows the diagnosis by more than half.
Yellow leaves are the most common plant complaint and the most commonly misdiagnosed. The usual response is to add a general fertiliser, which helps in maybe a third of cases and does nothing in the rest. The pattern of the yellowing tells you far more than the fact of it.
First, rule out the causes that are not nutritional
Before reading the chart, check three things. Overwatering is the single most common cause of yellow leaves on indoor plants, and it looks similar to nitrogen shortage. If the mix is soggy and the yellow leaves feel soft rather than dry, water is the problem, not fertiliser.
Low light causes even, gradual yellowing on the leaves furthest from the light source. Adding nutrients to a plant sitting in a dark corner makes no difference.
Natural ageing accounts for one or two lower leaves yellowing on an otherwise healthy plant. That is normal and needs no action.
The deficiency chart
Work down this table using the location of the symptom first, then the pattern.
The three you will actually meet most often
Nitrogen
Even, pale yellowing that starts at the bottom of the plant and moves up. The plant is moving nitrogen out of old leaves to feed new growth, which is why the pattern is so consistent. Any balanced feed corrects it. A water-soluble NPK 19:19:19 at 1 to 2 g per litre works, and you should see new green within a week.
Nitrogen shortage is normal in a plant that has been in the same potting mix for more than a year. Potting mix is not soil; it holds very little nutrient reserve.
Iron
Bright yellow leaf with a clear network of green veins, appearing on the newest leaves while older leaves stay green. This is the most distinctive pattern on the chart and the easiest to recognise once you have seen it.
The cause is usually not a lack of iron but alkaline water or mix locking it up. Hard tap water above pH 7.5 causes this reliably. The fix is chelated iron EDTA as a foliar spray at about 1 g per litre, which bypasses the soil chemistry entirely. Response is visible in five to seven days on new growth. Old damaged leaves will not turn green again.
Magnesium
Similar interveinal yellowing to iron, but on old leaves instead of new ones. Very common in plants fed heavily with potassium, because potassium and magnesium compete for uptake.
Magnesium sulphate, sold as Epsom salt, at 1 g per litre as a foliar spray corrects it quickly and cheaply.
When more than one nutrient is short
Mixed symptoms across old and new leaves usually mean the mix is exhausted rather than short of one specific element. In that case a chelated mix micronutrient covering zinc, iron, manganese, copper, boron and molybdenum is more sensible than guessing at individual elements. Apply as a foliar spray at about 1 g per litre.
Adding a humic and fulvic acid to the watering can improves what the roots can take up from an old, tired mix. It is not a fertiliser, but on a plant that has been in the same pot for two years it often produces more visible improvement than adding more feed.
A fortnightly seaweed extract helps a recovering plant push new roots, which is what actually ends the problem.
How to apply a correction to a houseplant
- Mix at the lower end of the label rate. Houseplants in small pots burn easily and the margin for error is smaller than in a garden bed.
- Spray in the evening or early morning, never in direct sun.
- Cover the underside of the leaves. That is where most absorption happens.
- Water the pot lightly first if the mix is bone dry, so the plant is not stressed when you feed it.
- Wait a full week before judging the result. Nothing works in two days.
Do not correct three things at once. If you spray iron, magnesium and a general feed together and the plant improves, you have learned nothing about what was wrong.
When it is time to repot instead
If a plant has been in the same mix for more than two years, if water runs straight through without wetting the mix, or if you can see a white salt crust on the surface, feeding will not solve it. The mix has broken down and lost structure.
Repot into fresh medium, trim any dead roots, and hold off on fertiliser for three weeks while the plant re-establishes.
Michigan State University Extension sets out a clear diagnostic sequence for this, including how to separate deficiency from root damage. It is a useful cross-check before you treat. The RHS also maintains a good visual reference for the individual deficiencies.
Take a photograph of the leaf when you first notice yellowing, and another a week after treatment. Memory is unreliable about colour, and the comparison tells you whether the diagnosis was right.
Frequently asked questions
1. Why are my plant leaves turning yellow?
The three most common causes are overwatering, low light and nitrogen shortage. Check the moisture in the mix first. If it stays wet for days after watering, the cause is water rather than nutrition.
2. How do I tell overwatering from a nutrient deficiency?
Overwatered leaves turn yellow but stay soft and limp, and the mix feels heavy and wet several days after watering. Deficiency yellowing follows a pattern, usually starting on either the oldest or the newest leaves, and the mix dries normally.
3. What deficiency causes yellow leaves with green veins?
Iron if it appears on the newest leaves, magnesium if it appears on the older ones. Both produce the same interveinal pattern, so the location on the plant is what separates them.
4. Will yellow leaves turn green again after treatment?
Usually not. A leaf that has lost its chlorophyll rarely recovers fully. Judge the treatment by the colour of the new growth that appears after it, not by the damaged leaves.
5. How quickly should a foliar spray show results?
Five to ten days for a visible change in new growth. If nothing has changed after two weeks, the diagnosis was probably wrong or the real problem is root damage.
6. Can hard tap water cause yellow leaves?
Yes. Water above about pH 7.5 locks up iron and manganese in the mix, producing interveinal yellowing on new leaves even when the nutrients are present. A chelated micronutrient spray bypasses the problem.
7. Is Epsom salt good for yellow leaves?
Only for magnesium deficiency, which shows as yellowing between the veins of older leaves. Used at about 1 g per litre it corrects that quickly. It does nothing for the other deficiencies.
8. How often should houseplants be fertilised?
Every two to four weeks during active growth, and much less or not at all in winter. Potting mix holds very little nutrient reserve, so plants in the same mix for over a year almost always need feeding.
9. Should I remove yellow leaves?
Once a leaf is more than about half yellow it is no longer contributing, so removing it is fine and tidies the plant. Do not strip many leaves at once from a struggling plant.
10. When should I repot instead of feeding?
If the plant has been in the same mix over two years, if water runs straight through without soaking in, or if there is a white salt crust on the surface. At that point the mix has broken down and no amount of feeding will fix it.
SOURCES CITED
Michigan State University Extension — Six Steps to Identifying Nutrient Deficiencies — https://www.canr.msu.edu/news/six_steps_to_identifying_nutrient_deficiencies_in_ornamental_plants
Royal Horticultural Society — Nutrient Deficiencies — https://www.rhs.org.uk/prevention-protection/nutrient-deficiencies
| Category | Global Garden |
|---|---|
| URL slug | /blog/gardening/yellow-leaves-nutrient-deficiency-chart |
| Primary keyword | yellow leaves on houseplants |
| Secondary keywords | plant nutrient deficiency chart, nitrogen deficiency symptoms plants, iron chlorosis houseplant, magnesium deficiency yellow leaves, why are my plant leaves turning yellow, interveinal chlorosis causes |
| Search intent | Diagnostic — plant owner is looking at a yellowing leaf right now and wants to identify the cause. |
| Meta title | Yellow Leaves on Houseplants: A Deficiency Chart (48 chars) |
| Meta description | Old leaves or new leaves? Veins green or yellow? Use this chart to identify which nutrient your plant is short of, and how to correct it. (137 chars) |
| Word count | ~1,700 |
| Internal links | Mix Micronutrient | Iron EDTA | Zinco Grow Zinc EDTA | NPK 19:19:19 | Seaweed Extract | Humic + Fulvic Acid | Boron 20% EDTA |
| External sources | Michigan State University Extension (six steps to identifying deficiencies) | RHS (nutrient deficiencies) |
| The quick test: if you cannot decide between overwatering and a deficiency, lift the pot. A pot that feels heavy several days after watering is holding too much water. Fix the drainage before you fix the nutrition. |
|---|
| What you see | Where | Likely cause | What to do |
|---|---|---|---|
| Whole leaf pale, then yellow, evenly | Old leaves first | Nitrogen | Balanced NPK feed at label rate; response in 7 to 10 days |
| Yellow between veins, veins stay green | Old leaves first | Magnesium | Epsom salt at 1 g per litre, or a micronutrient mix |
| Yellow between veins, veins bright green | New leaves first | Iron | Chelated iron as a foliar spray; check pH of water |
| Small new leaves, short spacing, yellow mottling | New leaves | Zinc | Chelated zinc, foliar |
| Yellow or brown scorched leaf edges | Old leaves | Potassium | Potassium-rich feed; also check for salt buildup |
| Growing tip dies, new leaves deformed | New growth | Calcium or boron | Steady watering; boron only at very low rates |
| Purple or reddish tinge, slow growth | Old leaves | Phosphorus | Phosphorus-rich feed; common in cold conditions |
| Pale overall, mix stays wet, soft leaves | Anywhere | Overwatering | Not a deficiency. Improve drainage and reduce frequency |
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