• oxide
Nitrogen Total (N) 0%
Phosphorus Pentoxide (P205) 0%
Potassium Oxide (K20) 0%
Iron (Fe) 17.80%
Water soluble 17.80%



3-4 Months

Product Code


Osmocote Iron 3-4M

Iron 3-4M


  • Advantages
  • Suggested application rates
  • Directions for use
  • Coated Ferric sulfate conveniently delivers a sustained supply of controlled release iron and sulfur in a safe and reliable manner.
  • Iron is part of the chlorophyll molecule. Iron helps maintain green foliage on iron inefficient plants. Although Osmocote Iron works in all conditions, it excels in areas with hard water.
  • Sulfur (S) is often lacking in growing system. Low S can lead to stunted, yellow plants.
  • Unlike with liquid iron drenches, the consistent release of Osmocote Iron eliminates the need for repeated applications, saving time, labor, and ultimately dollars. The continuous release in the root zone allows the plants to pick up iron throughout their growing cycle.
  • Products tested by ICL at both university trial sites as well as commercial growers.
Suggested application rates

The following application rates are intended for general container greenhouse production and nursery stock growing conditions.  Product and rate selection should always be based on individual grower practices and environmental conditions.  Some factors that influence selection include:

  • Climate
  • Specific Crop
  • Type of Growing Media
  • Other Nutrient Sources
  • Irrigation Type
  • Rainfall Amount
Common container sizes (Volume) Approx. No. of containers per Cubic Yard** Low High
Trade 1 Gallon 300 2 3
1 Gallon 210 2 4
Trade 2 Gallon 125 4 7
2 Gallon 102 4 9
3 Gallon 70 6 13
5 Gallon 52 9 17
7 Gallon 35 13 26


Larger Containers Surface Area in Sq. Ft. Low High
10 gal. - 17 in. diameter 1.4 16 31
15 gal. - 17.5 in. 1.5 17 34
20 gal. - 21 in. 2.3 26 52
25 gal. - 22,5 in. 2.8 31 63
30 gal. - 26,5 in. 3.8 43 85
45 gal. - 30 in. diameter 4.8 54 108
Other larger containers - use these rates multiplied by actual container surface in sq. ft. 11 22


Lb. per cubic yard 1 2
Kg. per cibic meter 0.6 1.2
Grams per liter 0.6 1.2
Directions for use

Osmocote Iron should be initially incorporated for plants grown in artificial/soilless media when possible. When upshifting to larger containers, application rate applies only to incremental growing media used. Mixing efficiency is improved if soil medium is dry prior to incorporation.

Osmocote Iron can be applied to the surface of the growing media or soil contains insufficient micronutrient levels. Broadcast granules as uniformly as possible over soil surface. Avoid piling product against leaves and stems. Water in immediately after application.

Click for Product Sheet

Osmocote® Iron, featuring unique E-Max Release Technology, is designed to maximize nutrient efficiency by supplementing iron and sulfur levels for high iron demanding crops, high root zone pH’s, high alkaline waters, and situations based on media/tissue testing where iron levels are shown to be deficient.