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
A quick yellow-leaf triage (before you add anything)
Before reaching for fertiliser, take 60 seconds to narrow down what’s actually going on. Yellow leaves almost always follow a pattern — and that pattern tells you where to look first.
1. Where is the yellowing showing up?
- Older, lower leaves first → often nitrogen or magnesium, or normal ageing
- New growth turning yellow → more commonly iron or pH-related lockout
2. What does the soil feel like right now?
Push a finger 5–7 cm into the soil.
- Bone dry and pulling away from the pot → underwatering stress
- Cold, wet or muddy → overwatering or poor drainage (roots can’t breathe)
3. Are there spots, holes or distorted leaves?
- Speckling, blotches or chewed edges → pests or leaf disease
- Even, gradual yellowing → more likely nutrition or root stress
4. Has anything changed recently?
Think back 1–3 weeks:
- Repotting or soil change
- Sudden cold snap or heatwave
- Moving plants indoors/outdoors
- A recent feed or pH adjustment
If the yellowing lines up with a change, that’s usually your clue.
Once you’ve ruled out water, roots and environment, then it’s time to look closely at nutrients — starting below.
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.
- N: Fish Hydrolysate
- Fe: Fe source / trace mineral top-up
- Mg: Epsom Salts or Kieserite
Lasting fix (weeks): Build resilient media and mineral balance.
- Slow N: Soybean Meal
- Traces & Fe: Glacial Rock Dust (High Iron)
- Mg & K balance: SOPM / K-Mag
- Buffer/pH support: Dolomite Lime or Basalt (use judiciously; test pH)
Other nutrient deficiencies that can cause yellow leaves
While nitrogen, iron and magnesium are the most common culprits, a few other nutrients can also cause yellowing under certain conditions.
|
Nutrient |
Common signs |
Typical cause |
|---|---|---|
|
Calcium (Ca) |
Yellowing or distorted new growth, weak tips |
Poor uptake due to irregular watering |
|
Potassium (K) |
Yellowing or browning along leaf edges |
Leached soils or heavy rainfall |
|
Zinc (Zn) |
Yellowing between veins on younger leaves |
High pH soils or long-term deficiency |
These are far less common in healthy, living soils and are often linked to pH imbalance or root stress, not a lack of fertiliser in the soil itself.
Don’t Misdiagnose — Rule These Out First
- Overwatering/poor drainage: Soggy pots mimic nutrient issues. Check drainage and pot weight.
- Low light / seasonal shift: Winter light or deep shade can yellow lower leaves.
- Cold shock or root damage: Recent repotting, pests, or cold snaps slow uptake.
- pH out of range: Quick media test; correct first to avoid “feeding into lockout.”
Skip the guesswork → Fix Yellow Leaves Collection
Other common causes of yellow leaves (often mistaken for deficiencies)
Not all yellow leaves mean your plant is hungry. These issues can cause the same symptoms — and adding nutrients won’t fix them.
Cold stress & heat stress
Sudden temperature swings can interrupt nutrient uptake even when soil nutrition is fine.
- Cold stress often shows as pale or yellowing leaves after cold nights or winter moves.
- Heat or sun stress can cause yellowing with scorched edges or patches.
If temperatures stabilise, plants often recover without feeding.
Root-bound plants & compacted soil
Roots need oxygen as much as nutrients.
- Plants that are root-bound or growing in compacted soil struggle to absorb nutrients.
- Tip the pot gently and check roots — healthy roots are light-coloured and firm, not dark or mushy.
If roots are circling tightly or the mix stays wet for days, repotting or soil aeration will help more than fertiliser.
Pests & leaf disease
Yellowing combined with:
- Spots, mottling or sticky residue
- Deformed or speckled leaves
…can point to pests (like mites or aphids) or leaf disease rather than nutrition.
Address the pest or disease first — feeding during active infestations often makes things worse.
The Safe-Use Checklist (Organic & Indoor-friendly)
- Follow label rates; spot-test on one plant or leaf before full coverage.
- Foliar in cool hours (early morning/late arvo); never in full sun.
- “Little and often” beats big dumps in living soils.
- Shake liquids before use; store minerals dry and sealed.
- 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.
Can yellow leaves turn green again?
Sometimes. If the cause is caught early (like iron deficiency or mild nitrogen stress), new growth usually returns green first. Severely yellow leaves rarely recover fully.
Should I remove yellow leaves?
Yes — once they’re mostly yellow. Removing them helps redirect energy to healthy growth and reduces disease risk.
How long does it take to see improvement after fixing the cause?
- Iron: 7–14 days on new growth
- Nitrogen or magnesium: 2–4 weeks
- Watering or drainage fixes: often within days
Is it overwatering or underwatering?
Check the soil, not the calendar. Consistently wet soil points to overwatering or drainage issues. Dry soil throughout the pot points to underwatering.
What soil pH should I aim for?
Most plants prefer pH 6.0–6.8. Outside this range, nutrients may be present but unavailable — a common reason yellowing persists despite feeding.
Still seeing yellow?
Get the right input for your plant today.
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