Yellowing leaves (aka chlorosis) can sneak up on even the best growers. The good news: most cases come down to a few common nutrient issues you can spot in under a minute. In this guide we’ll help you quickly tell Nitrogen vs Iron vs Magnesium deficiency, rule out the usual suspects (overwatering, pH, low light), and pick the right organic fix. Prefer to shop by problem? Jump straight to our curated collection: Fix Yellow Leaves
Quick Diagnosis — Which Yellow Is It?
Nitrogen (N) deficiency — mobile nutrient
What you’ll see: Older/lower leaves fade to pale green → uniform yellow. Whole plant can look washed-out and growth slows.
Often happens when: Fast growth, spent potting mix, heavy feeders, cool/wet weather slowing mineralisation.
Quick fix (this week): Liquid organic N for a gentle green-up (e.g., Fish Hydrolysate)
Season-long fix: Slow-release organic N in the root zone (e.g., Soybean Meal)
Tip: Expect visible improvement on new growth first.
Iron (Fe) deficiency — immobile nutrient
What you’ll see: New leaves turn yellow but veins stay green (classic interveinal chlorosis); older leaves look okay.
Often happens when: Media pH too high, over-liming, cold/wet roots, excess P; common in calcareous mixes and some ornamentals/citrus.
Quick fix (this week): Apply a readily available Fe source such as Glacial Rock Dust and address pH drift.
Season-long fix: Add broad-spectrum trace minerals (e.g., Glacial Rock Dust (High Iron) and maintain root-zone pH in range.
Tip: Fe issues show fastest on the newest growth.
Magnesium (Mg) deficiency — mobile nutrient
What you’ll see: Yellowing between veins on older leaves; margins can scorch if severe; new growth can stay green.
Often happens when: Coco/soilless mixes, high K/Ca inputs, heavy fruiting plants, container citrus/veg.
Quick fix (this week): Epsom Salts (Magnesium Sulphate) as a foliar or soil drench; or Kieserite (Mg) for mixing with soil.
Season-long fix: Balance base saturation; consider Sulphate of potash magnesia / K-Mag (K+Mg+S) where K is also needed.
Tip: Mg is mobile — fixes show first on new growth, while damaged old leaves don’t fully recover.
Quick Fix vs Lasting Fix (How to choose)
Quick fix (days): Liquids and foliars to stabilise photosynthesis fast — always follow the on-pack label.
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Fe: Fe source / trace mineral top-up
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Mg: Epsom Salts or Kieserite
Lasting fix (weeks): Build resilient media and mineral balance.
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Slow N: Soybean Meal
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Traces & Fe: Glacial Rock Dust (High Iron)
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Mg & K balance: SOPM / K-Mag
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Buffer/pH support: Dolomite Lime or Basalt (use judiciously; test pH)
Don’t Misdiagnose — Rule These Out First
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Overwatering/poor drainage: Soggy pots mimic nutrient issues. Check drainage and pot weight.
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Low light / seasonal shift: Winter light or deep shade can yellow lower leaves.
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Cold shock or root damage: Recent repotting, pests, or cold snaps slow uptake.
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pH out of range: Quick media test; correct first to avoid “feeding into lockout.”
Skip the guesswork → Fix Yellow Leaves Collection
The Safe-Use Checklist (Organic & Indoor-friendly)
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Follow label rates; spot-test on one plant or leaf before full coverage.
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Foliar in cool hours (early morning/late arvo); never in full sun.
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“Little and often” beats big dumps in living soils.
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Shake liquids before use; store minerals dry and sealed.
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Re-check symptoms after 5–7 days; adjust only if needed.
| Symptom Snapshot | Likely cause | Quick fix (days) | Season-long fix (weeks) | |
|---|---|---|---|---|
| Older leaves uniformly pale/yellow | Nitrogen | Liquid N (Fish Hydrolysate) | Slow N (Soybean Meal), compost inputs | |
| New leaves yellow, veins green | Iron | Fe source / trace minerals | Glacial Rock Dust, correct pH | |
| Yellow between veins on older leaves | Magnesium | Epsom Salts / Kieserite | SOPM / K-Mag, balance base saturation |
FAQs
Can I just use Epsom Salts for any yellow leaf?
No — Epsom Salts fix magnesium issues. If new leaves are yellow with green veins, that points to iron instead. Match the symptom first.
How fast should I see results?
Foliars often show improvement within a few days. Soil fixes build over 1–2 weeks. Look for healthier new growth rather than perfect old leaves.
Do I need to flush pots first?
Only if you suspect salt build-up or severe pH drift. Otherwise, correct the root cause and water to light runoff.
Is fish hydrolysate safe for indoor plants?
Yes when used as directed. Apply lightly, ensure airflow, and avoid foliar feeding in direct light.
What’s the ideal pH range?
Most container edibles and ornamentals prefer roughly 5.8–6.5 in soilless mixes and 6.2–6.8 in soil. Always verify with your media and plant type.
Still seeing yellow? Get the right input for your plant today.
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