Developing affordable and effective organic growing media

April 15, 2019

As the demand for organically certified products builds, Gro-Bark is seeing increasing request for organic growing media. Gro-Bark has a long term goal of developing a fully approved growing media for use in organic agriculture. As part of that goal, Gro-Bark designed a trial to evaluate three organic surfactants, in combination with two organic starter fertilizers, in comparison to Gro-Bark’s typical chemical based surfactant and starter fertilizer.

Trial Objective

The objective of the trial was to identify which organic surfactant and starter charge fertilizer work best together and perform at a similar efficacy to Gro-Bark’s traditional chemical based surfactant and starter charge. The chemical-based products currently being used at Gro-Bark are AquaGro and Pre-Mix 6; these products serve as the control for this trial. The three organic surfactants examined in the trial were FiberGro, Penetrate 50, and Natural Wet. The organic fertilizers were Gallant 3-3-3 and Gallant 5-2-5, each at two different rates.


In all plant productivity measurements, the organic treatments did not demonstrate any statistically significant differences from AquaGro and Pre-Mix 6. All treatments demonstrated the same plant growth and health, regardless of fertilizer of surfactant. The second objective was to determine which combination of organic surfactant and starter fertilizer charge performed best. While Natural Wet was the most consistently well-performing surfactant, all surfactants performed similarly. Gallant 5-2-5 at 0.31 kgN/yd3 and Gallant 3-3-3 at 0.32 kgN/yd3 had the overall highest ECs and growth indexes. Considering the similarity between treatments and the cost of materials, Gro-Bark recommends that Penetrate 50 with Gallant 3-3-3 at 0.32kgN/yd3 as the optimal combination for use in organic growing media. With this choice, Gro-Bark can confidently offer growers a good product for an affordable price.