1. Read the pattern first
Which leaves are yellow, and how, tells you almost everything.
New leaves yellow, veins still green → iron or manganese deficiency. The classic Miami pattern.
Older leaves yellow uniformly, new growth green → nitrogen deficiency. Responds to normal fertiliser.
Older leaves yellow at the margins working inward → often potassium or magnesium. Common on palms.
Whole plant yellowing, soil wet, growth stalled → over-watering or poor drainage.
Yellowing following the sprinkler pattern → possibly salty irrigation water. See our salt guide.
2. Why Miami soil causes it
Much of Miami-Dade is sand over limestone. Limestone is calcium carbonate, and as it dissolves it pushes soil pH upward, frequently to 7.5 or higher.
At that pH iron and manganese convert to forms plants cannot absorb. A soil test may show adequate iron while your plant is visibly starving for it. The nutrient is there; the plant cannot reach it.
This is why adding more standard fertiliser does not help. Certain plants show it readily — ixora, gardenia, citrus and many palms — while natives adapted to alkaline soil rarely do.
3. How to correct it
Short term — foliar spray. A chelated micronutrient spray on the leaves bypasses soil chemistry entirely. Response is usually visible within one to two weeks. Spray early morning or late afternoon, never midday.
Medium term — chelated soil application. Use a chelated iron product. Plain iron sulphate locks out almost immediately at high pH.
Long term — change the feeding programme. Use a slow-release fertiliser with iron, manganese, zinc and magnesium included, applied lightly every six to eight weeks through the growing season.
Also long term — add organic matter. Mulch and compost slightly lower surface pH as they break down and improve nutrient retention in sand.
4. What will not work
- More nitrogen fertiliser. Wrong nutrient. You push more new growth that emerges just as yellow.
- More water. Can worsen it — saturated soil reduces uptake further.
- Plain iron sulphate. Locks out almost immediately in alkaline soil.
- Replacing the plant. The new one does the same thing in the same soil.
5. Preventing it
- Choose adapted plants. Florida natives rarely show chlorosis. If a plant needs constant iron to look acceptable, it may be wrong for the site.
- Amend at planting and mulch generously.
- Feed correctly from the start with a micronutrient-inclusive product rather than waiting for symptoms.
- Avoid planting susceptible species against fresh concrete. Curing concrete leaches lime and raises local pH further.
Send a photo close enough to see the leaf veins. Deficiency patterns are usually readable at a glance and the correction is normally inexpensive. Send it over.