Developing an Organically Approved Soil Mix for Use in Vegetable Transplant Production

A constraint to the production of vegetable transplants that meet organic regulations is the lack of locally available, organically-approved commercial soil mixes or a specific and reliable formulation and methodology for an approved organic mix that could be produced on-farm. Commercial soil mixes are used because of the difficulty of producing an acceptable on-farm mix that is economical, consistent, and uniform and which promotes good germination and subsequent plant growth.

In California, where the largest concentration of organic production is located, there are companies that manufacture organic soil mixes for the organic market. However, shipment of such products to the Southern Region is cost-prohibitive. In Florida, as in much of the Southern Region, there is no locally available, organically-approved commercial soil mix. This research project addressed the needs of organic producers in the Southern Region by developing formulation recommendations of soil mixes that could be applied to various on-farm operations.

We developed a number of formulations through a series of experiments at the University of Florida and on Rosie’s Organic Farm which identified optimal growth media for a number of vegetable species. Organic farmers throughout the Southern Region should test these formulations on their farm to determine those that work optimally in their operations. Growers may have to adjust the concentration of organic amendments in the mixes to obtain the type of transplant growth that they desire. However, these formulations provide the framework upon which an optimal organic transplant production system can be obtained. Using organic amendments, healthy lettuce transplants were produced which favorably compared to those produced using a high input synthetic fertilizer. For information on these formulations, please contact Rose Koenig.