Domakihub How to Treat Iron Chlorosis in Citrus Trees
Restore yellow citrus leaves to deep green using chelated iron and soil-pH correction.
Reviewed by Domakihub garden pros · 2026-06-23 · 5 min read
Citrus trees grown in Greek alkaline soils frequently develop iron chlorosis — a condition where leaves turn pale yellow between the veins while the veins themselves stay green. The video above demonstrates how to identify and treat iron deficiency in citrus clearly, and this article walks you through the exact steps to diagnose the problem, correct soil pH, and apply the right iron chelate so your lemon, orange, or mandarin trees return to full productivity. Whether you manage a private home garden, a holiday rental with citrus in the courtyard, or a hotel landscaped with fruit trees, this guide gives you a repeatable fix.
Why Greek Soils Cause Iron Chlorosis
Greece's limestone-heavy geology pushes garden soil pH well above 7.5 in many regions, particularly in the Peloponnese, Crete, and the Aegean islands. At those pH levels, iron in the soil converts to insoluble iron hydroxide that roots simply cannot absorb — even if the soil contains plenty of iron in raw form. The result is classic interveinal yellowing that spreads from young leaves outward.
Irrigation with hard tap water compounds the problem over time. Each watering deposits calcium carbonate in the root zone, nudging pH higher still. This is why citrus planted in pots or raised beds can develop chlorosis faster than trees in open ground, and why treating the symptom without correcting soil chemistry only buys a few weeks of relief.
Chlorosis vs. Other Nutrient Deficiencies
Iron chlorosis shows a very specific pattern: the leaf blade turns yellow or lime green, but the veins remain distinctly darker green, most visibly on new growth at the branch tips. This interveinal pattern on young leaves is the key diagnostic clue. Nitrogen deficiency, by contrast, yellows older leaves first and evenly. Magnesium deficiency also causes interveinal yellowing but starts on mature leaves. Zinc and manganese shortages create similar patterns to iron but respond to different treatments, so correct diagnosis before spending money on amendments.
A simple soil pH test — available at any Greek agricultural supply shop (agrotiko) — is the fastest confirmation. If your reading is above 7.0 and your citrus shows new-growth yellowing with green veins, iron chlorosis is the most likely cause. You can also send a leaf sample to the nearest regional ELGO-DIMITRA agriculture office for a full nutrient analysis if the picture is unclear.
Five Steps to Restore Green Leaves
- 1
Test and record your soil pH
Buy an inexpensive pH meter or test kit from any agrotiko and take readings at three spots around the drip line of each affected tree. Note the results. If pH is above 7.2, every treatment you apply will work better and last longer once you also address the alkalinity. Retest after amendments to track progress.
- 2
Acidify the root zone with elemental sulfur or acidifying fertilizer
Broadcast elemental sulfur (θείο) at 100–200 g per square metre of root zone and work it lightly into the top 5 cm of soil. Soil bacteria convert sulfur to sulfuric acid over four to eight weeks, lowering pH by 0.5–1.0 units. For faster results, water in an acidifying fertilizer (ammonium sulfate or a product labelled 'for acid-loving plants') at the package rate. Repeat every season to counteract ongoing hard-water irrigation.
- 3
Apply chelated iron (EDDHA chelate) as a soil drench
EDDHA chelate (sold in Greece as 'σιδηροχηλικό EDDHA' or under brand names like Sequestrene 138 Fe) remains available to roots even at pH 8.0–9.0, making it far more effective in alkaline conditions than cheaper EDTA or ferrous sulfate formulations. Dissolve 5–10 g per tree in 10 litres of water and pour evenly around the root zone, keeping product away from the trunk. Apply in early spring as growth resumes, and again in early autumn if yellowing persists.
- 4
Use foliar iron spray for a rapid cosmetic recovery
While soil treatments correct the root cause, a foliar spray of ferrous sulfate (1–2 g per litre of water) or a chelated iron foliar product gives visibly greener leaves within 7–14 days. Spray in the early morning or late afternoon to avoid leaf burn, ensuring thorough coverage on both sides. Foliar application does not fix the underlying soil problem, but it sustains photosynthesis and fruit set while the soil chemistry improves.
- 5
Mulch, monitor, and repeat annually
Apply a 5–8 cm layer of composted wood chips or pine bark around the drip line, keeping mulch 15 cm clear of the trunk. Organic mulch slowly releases organic acids, moderates soil temperature, retains moisture, and gradually buffers alkalinity. Check new growth colour every four to six weeks after treatment. If you see fresh yellow leaves emerging at tips, repeat the EDDHA drench. Establish an annual spring routine — soil acidifier plus chelated iron — so trees stay productive season after season.
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FAQ
- Can I use ferrous sulfate instead of EDDHA chelate in my Greek garden?
- Ferrous sulfate is cheap and works well in neutral or mildly acidic soils (pH 6.0–7.0). In typical Greek alkaline soils above pH 7.5 it converts to insoluble hydroxide within days of application, delivering very little iron to the roots. EDDHA chelate is specifically engineered to stay soluble and plant-available up to pH 9.0, so it is strongly preferred for most Greek citrus situations. Use ferrous sulfate only as a foliar spray, not as a soil drench, where soil pH is the limiting factor.
- How long does it take for citrus leaves to turn green again after treatment?
- Foliar iron sprays produce visible greening in one to two weeks. Soil EDDHA drenches take three to five weeks to show results in new growth because the tree must grow new leaves that absorb properly chelated iron through healthy roots. Already-yellowed leaves will not fully regreen — the improvement is visible in the next flush of new growth emerging from the branch tips. Full canopy recovery across a mature tree typically takes one full growing season of consistent treatment.
- My citrus is in a pot on a hotel terrace. Does the same approach apply?
- Yes, but potted citrus needs more frequent attention because alkaline salts from tap water accumulate rapidly in the limited soil volume. Use a specialist citrus potting mix with a pH of 5.5–6.5, flush the pot thoroughly with water every month to leach out calcium deposits, and apply half the EDDHA drench dose every six to eight weeks through the growing season. Repotting into fresh acidic mix every two to three years is also advisable. Terrace trees in direct Greek summer sun may also need micro-irrigation to prevent the additional stress of drought, which worsens chlorosis symptoms.