High-purity manganese sulfate — 31% Mn and 18% S — for preventing and correcting manganese deficiency in palms, citrus, vegetables, and hydroponic systems. The go-to solution for frizzle top in palms and interveinal chlorosis across high-pH and sandy soils.
Essential for palm health — helps prevent the progressive frizzle top condition most common in Queen, Royal, Pygmy Date, and Coconut Palms.
Activates more than 30 plant enzymes critical to photosynthesis, nitrogen metabolism, and energy transfer throughout the plant.
Manganese is required for the oxygen-evolving complex of photosystem II — the water-splitting reaction that powers photosynthesis and enables plants to convert light into energy.
Fine crystalline powder independently tested for heavy metals — results consistently well below required limits — for reliable, consistent results every application.
Registered with the California Department of Food and Agriculture — meets all regulatory standards for use on California crops.
Promotes lignin formation in cell walls, improving structural integrity and supporting the plant's natural defense mechanisms against environmental stressors.
The sulfur component supports protein synthesis, improves nitrogen utilization, and enhances overall plant metabolic function.
Dissolves completely for use in drip irrigation, fertigation systems, hydroponic reservoirs, and foliar spray programs.
Effective via broadcast soil application, banding, foliar spray, fertigation, and hydroponic nutrient solution — one product, every method.
The 50 lb size is repackaged from OMRI Listed® material, making it suitable for use in certified organic production. Verify current approval with your certifying agency before use.
Our manganese sulfate is produced from a single, high-purity crystalline source — ensuring complete solubility and rapid plant uptake for quick deficiency correction.
MnSO₄·H₂O — crystalline powder delivering 31% elemental manganese and 18% sulfur. The monohydrate form dissolves readily in water and is readily available for plant uptake across a wide pH range.
Required for the oxygen-evolving complex of photosystem II — the water-splitting reaction that produces the oxygen released during photosynthesis. Without adequate manganese, this reaction fails and plants cannot generate energy from light.
Essential building block of the amino acids cysteine and methionine, and a component of coenzymes involved in nitrogen fixation. Sulfur can also support local acidifying effects in the rhizosphere over time, which may improve manganese availability in alkaline conditions.
Manganese is most commonly deficient in high-pH soils (above 7.0), sandy soils low in organic matter, and over-limed soils — conditions where Mn²⁺ ions bind to soil particles and become unavailable for root uptake. Poorly drained soils can cause the opposite: manganese toxicity where reduced Mn²⁺ accumulates to harmful levels. The sulfur in our formula can support local acidifying effects in the rhizosphere over time, which may help improve Mn availability in alkaline soils.
Frizzle top is a progressive manganese deficiency disorder affecting palms. New fronds emerge chlorotic and undersized (early stage), then become withered, scorched, and distorted — giving the characteristic "frizzled" appearance (middle stage). In the late stage, only small brown stubs emerge from the spear, followed by palm death if left untreated. Because manganese is immobile in the plant, deficiency always appears on the newest growth first. Regular preventive applications every three months are far more effective than attempting to correct advanced frizzle top.
| Application Method | Rate | Notes |
|---|---|---|
| Broadcast (Pre-plant) | 20–60 lbs/acre | 0.5–1.4 lbs/1,000 sq ft; confirm rate with soil test |
| Banded/Side-dress | 10–30 lbs/acre | More efficient than broadcast in high-pH soils |
| With Ammonium Sulfate | Add 50+ lbs/acre | Improves Mn availability in alkaline soils |
| Home Gardens | 1–2 lbs/1,000 sq ft | Work into top 4–6 inches of soil |
| Severity | Rate per 100 Gallons | Frequency |
|---|---|---|
| Nutritional Maintenance | 1 lb | Monthly during active growth |
| Mild Deficiency | 1–2 lbs | Every 2–3 weeks |
| Severe Deficiency | 3 lbs | Weekly until corrected; test on a small area first |
| Palm Size | Rate per Tree | Frequency |
|---|---|---|
| Small/Young | 2–4 oz | Every 3 months |
| Medium | 4–8 oz | Every 3 months |
| Large/Mature | 8–16 oz | Every 3 months |
| Severely Deficient | Double rates | Monthly until recovery; consult a certified arborist for severely affected specimens |
| Application | Rate | Notes |
|---|---|---|
| Hydroponics | 0.5–2 ppm Mn | In completed nutrient solution |
| Fertigation | 1–2 lbs/acre per application | Through drip or overhead irrigation |
In alkaline soils (pH above 7.0), manganese rapidly oxidizes to unavailable forms. Applying 50+ lbs/acre of Ammonium Sulfate alongside your manganese sulfate creates acidic microsites around roots, which can significantly improve Mn uptake without requiring a full soil acidification program.
For chemical emergencies contact CHEMTREC: +1-703-527-3887. Refer to the Safety Data Sheet (SDS) for complete safety information.
EDTA-chelated manganese stays plant-available in high-pH soils where sulfate forms are rapidly immobilized. The preferred choice for alkaline conditions.
Iron and manganese deficiencies often co-occur in the same soils. Correct both simultaneously for faster recovery of chlorotic plants.
Zinc works alongside manganese in enzyme systems supporting plant growth and development. A natural pairing for complete micronutrient programs.
Select any question to expand the answer.
Manganese sulfate is a water-soluble micronutrient fertilizer providing 31% manganese and 18% sulfur. Manganese is essential for the oxygen-evolving complex of photosystem II — the water-splitting reaction that powers photosynthesis and enables plants to convert light into energy. Without it, plants cannot function normally. Manganese also activates more than 30 plant enzymes involved in nitrogen metabolism, chlorophyll function, and structural support through lignin formation. The sulfur component contributes to protein synthesis and can support local acidifying effects in the rhizosphere over time, which may improve manganese availability in alkaline soils.
For a deeper look at how manganese and potassium interact in plant nutrition, see: What is the Role of Manganese and Potassium?
Frizzle top is a progressive manganese deficiency disorder affecting palms. New fronds emerge chlorotic, undersized, and weak in the early stage. As deficiency worsens, fronds become withered, scorched, and distorted — the "frizzled" appearance that gives the condition its name. In advanced cases, only small brown stubs emerge from the spear, eventually leading to palm death.
Most susceptible species are Queen Palms, Royal Palms, Pygmy Date Palms, Paurotis, and Coconut Palms. Because manganese is immobile in plant tissue, deficiency symptoms always appear on new growth first — making early intervention critical. Preventive applications every 3 months are more effective than trying to rescue severely affected palms.
The most reliable indicator is interveinal chlorosis on young leaves — the tissue between veins turns yellow or pale green while the veins themselves remain green. This contrasts with iron deficiency, which looks similar but can be distinguished by soil pH and the specific crop affected. Other symptoms include gray specks or necrotic spots on leaf tissue (common in cereals), stunted growth, reduced fruit set, and delayed maturity.
Manganese deficiency is most common in soils with pH above 7.0, sandy soils with low organic matter, over-limed soils, and waterlogged soils where Mn converts to unavailable oxidized forms. A soil or tissue test is the most reliable confirmation before applying. For more on diagnosing nutrient deficiency symptoms, see: 8 Reasons Why Your Plant Leaves Are Turning Yellow
Foliar spray is often the most efficient method for rapid correction — 1–3 lbs per 100 gallons delivers manganese directly to leaf tissue, with visible improvement in new growth often appearing within 1–2 weeks. Best applied before full leaf expansion. Always test on a small area first.
Soil application (20–60 lbs/acre broadcast, 10–30 lbs/acre banded, based on soil test) is longer lasting but less efficient due to soil tie-up in high-pH conditions. Adding 50+ lbs/acre ammonium sulfate can significantly improve Mn availability. For palms, apply 2–16 oz per tree to soil under the canopy every 3 months. For hydroponics, target 0.5–2 ppm in the completed nutrient solution — use the calculator on this page for exact dosing.
To understand how sulfur works alongside manganese in plant nutrition, see: What is the Function of Sulfur in Plants?
The 50 lb size of our manganese sulfate is repackaged from OMRI Listed® material, which means it may be suitable for use in certified organic production where soil manganese deficiency is documented. Other sizes carry CDFA registration but are not repackaged from OMRI Listed® material.
Organic compatibility requirements vary by certifying agency. Always verify current approval status with your certifier before use, and keep documentation of your soil deficiency on file as most certifiers require it to justify micronutrient applications.
Manganese sulfate (MnSO₄) releases Mn²⁺ ions directly into the soil solution. It is cost-effective and works well in moderately acidic to neutral soils (pH 5.5–7.0) where ionic manganese remains available. In soils above pH 7.0, Mn²⁺ can rapidly oxidize to unavailable Mn⁴⁺ forms, reducing effectiveness.
Chelated Manganese EDTA binds manganese in an organic cage that resists pH-driven oxidation, keeping Mn plant-available across a wider pH range including alkaline soils. Chelated forms cost more per unit but the difference is justified in high-pH conditions where sulfate forms would be largely immobilized. For a detailed comparison of sulfate and chelated micronutrient sources, see: Sulfate vs. Chelated Fertilizers
If you're not completely satisfied with your purchase, we offer a 90-day money-back guarantee. Return the unused portion in its original packaging and we'll process a full refund — no questions asked.
1% of all profits go to our foundation, focused on improving educational opportunities for children.
With over 35 years in business, Greenway Biotech, Inc. is a family-owned specialty fertilizer and wellness products manufacturer based in Madera, California. We hold CDFA registration for our fertilizer line and are committed to third-party testing, technical accuracy, and regulatory compliance — making us a trusted source for commercial growers and home gardeners alike.
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