1/15/2024 - By Dr. Aaron Palmateer

Harrell’s POLYON® 18-6-12 Mini NPK has a much smaller prill size than regular POLYON® fertilizer but is still manufactured with the same proprietary reactive-layer coating technology that ensures consistency and durability with every particle. Unlike other controlled-release fertilizers, the POLYON® 18-6-12 Mini NPK will not crack or release prematurely, which means consistent, predictable nutrient release that is safe and reliable for plants in the greenhouse and nursery.

Advantages of Harrell’s POLYON® 18-6-12 Mini NPK

The smaller-sized granules allow for uniform distribution providing approximately eight times more fertilizer prills per pot when compared to regular size POLYON® fertilizer granules. The smaller size granules allow for controlled-release fertilizer to be used in smaller containers, making it an excellent choice for propagation.



The 18-6-12 Mini NPK is a general-purpose formulation that lasts for 3 months making it suitable for a wide variety of plant species. Mini NPK can be incorporated or applied as a topdressing for established hanging baskets and perennials and is safe for long-term feeding of crops such as some succulents and interior foliage plants.

Environmental and Space Impacts of POLYON® 18-6-12 Mini NPK

Harrell’s 18-6-12 Mini NPK provides a solution for the use of controlled-release fertility in a smaller container, such as in greenhouse production where plants are produced in flats, trays, and smaller container sizes. Many of these operations and especially plant propagators have had to rely predominately on the use of continuous liquid feed for plant nutrition. Now, they can reap the benefits of using POLYON® controlled-release fertilizer, starting with reducing the feast-famine-fertility cycle and allowing for growers to turn off irrigation during cloudy weather.

This ability contrasts to liquid feed which would saturate the medium creating favorable conditions for root rot. The issue of over-spraying liquid fertilizer when going between round and square containers would no longer be a concern and there would be less overall worry about the impact of wind and rain.

Reach Out to Your Harrell’s Rep About POLYON® 18-6-12 Mini NPK

POLYON® controlled-release fertilizer eliminates repeated liquid feed applications, saving time and labor costs, plus it increases shelf life by providing nutrition to actively growing plants in transportation and while at the store. Healthy and vibrant plants mean a greater opportunity for sales and satisfied customers and POLYON® 18-6-12 Mini NPK can help achieve that.

Reach out to your local Harrell's Rep today for more information.