Page 17 - Griffin Gazette - March 2025

INTRODUCTION
Griffin Greenhouse Supplies provides technical support and cultivation inputs
for cannabis and edible producers of all sizes across the country. Water soluble
fertilizers (WSF) are a major input for most production strategies within these
industries due to their flexibility in nutrient delivery, numerous options available,
and cost in use. Growers should not be afraid to continuously search for ways
to enhance fertilizer programs through identifying high quality sources that are
reliable and competitively priced. Moreover, understanding that “things are not
set in stone” when creating and adjusting a fertilizer plan can empower growers
to make strategic changes that maximize yields, enhance quality, and drive
profitability. This article will touch on some of the services Griffin’s GGSPro team
provides as well as important considerations to be aware of when building and
manipulating fertilizer strategies.

STEP 1: KNOW YOUR WATER & KNOW YOUR SYSTEM
Although the use of reverse osmosis (RO) filtration is common within CEA, many
growers will forgo this technology in hopes of working with their existing irrigation
water source. With that said, “what’s in your water?” is a very important question
GGSPro will be asking before creating a fertilizer program. Be sure to use a
reliable horticultural water testing lab such as JR Peters, the producers of Jack’s
Fertilizers (Lab Testing Services - JRP Lab Services | Allentown, PA | JR Peters
Inc) to ensure the proper analytes are being measured. Regardless of whether
your water source comes from a well, pond, or municipality, water quality can vary
significantly by location and change over time, making annual water testing the
minimum recommendation.

The easiest way to think about it is that the salts in your water can be considered
“free fertilizer” that contribute to our overall nutrient targets such as calcium (Ca+),
magnesium (Mg+), and iron (Fe+2). Some water components such as alkalinity
(HCO3-), sodium (Na+), and chloride (Cl-) can provide challenges to production
when they are provided in excess amounts. Ensuring the optimal pH of your
growing media also falls into understanding your starting water quality. High
alkalinity water sources may require acid injection (e.g., sulfuric, phosphoric,
nitric, or citric acid) to prevent continual rise in media pH over time which leads
to micronutrient deficiencies. In hydroponic situations or when inert hydroponic
media is used, managing both the solution pH and alkalinity are equally important.
Besides water quality, your current or future infrastructure will directly impact how
we plan to deliver nutrition to plants. The use of bulk reservoirs versus stock tanks
with injectors as well as knowing how they are oriented, connected, or isolated
within your facility will come into play as a fertilizer plan is being developed and
adjusted. Infrastructure can provide benefits or limitations to optimizing nutrition
and reducing labor. Reach out to Griffin’s Construction Department on ways you
can increase flexibility within your current or future production space.

Continued 

GRIFFIN GAZETTE 2025 | 17