My Cart


Sulfate of Potash Magnesia 0-0-21.5

Regular Price
$ 17.99
Sale Price
$ 17.99
Regular Price
$ 17.99
Sold Out
Unit Price

NOTE: Depending on your shipping address, we may ship 50 pound items as two 25 pound bags.


Greenway Biotech's Sulfate of Potash Magnesia, also known by the brand name K-MAG or Sul-Po-Mag, is a Potash Fertilizer containing Potassium 21.5%,10.8% Magnesium, and 22% Sulfur. It has a very low percentage of Chloride  (under 2.5%), which minimizes the potential for fertilizer "burn". This is a great fertilizer for sensitive vegetables and fruit crops requiring high fertilizer rates. It is also beneficial to crops demanding high Potash and Magnesium that may be sensitive to Chloride. Because of its crystalline nature, Sulfate of Potash Magnesia dissolves gradually throughout the growing season. Sulfate of Potash Magnesia has neutral pH level, this is a very good source of Potash and Magnesium for areas with acidic soil since this wouldn't add to the acidity of the soil.

Sulfate of Potash Magnesia breaks down in the soil completely, meaning crops have access to three essential nutrients:

Potassium – Essential for protein synthesis and protein formation. It improves the flavor and color of fruits and vegetables and promotes drought tolerance, winter hardiness, and disease and insect resistance.

Magnesium – Resides at the heart of the pigment-containing molecule, chlorophyll. As rates of photosynthesis decline, so do quality and yield.

Sulfur – Remains a key element in crop proteins. It is a requirement for nitrogen fixation in legumes and vital to vitamin synthesis in all plants, important determinants of crop quality. Without sulfur, onions, garlic, and mustard would not possess their distinctive flavors.


Application Rate:

Soil: Broadcast 10 lbs. per 1,000 sq. ft.



Related Blog Posts:




Frequently Asked Questions:

Customer Reviews

Customer Reviews

Based on 18 reviews Write a review