Media Storage Basics By Todd Cavins

Quality manufacturers of growing media products, peat moss and aggregates strive to produce and deliver products in a safe environment that ensures product freshness. Herbicides or other harmful chemicals are not kept in or near the manufacturing facilities. Every effort is made to select shipping carriers that are reputable and agreements require them to operate clean trailers. In order to ensure your satisfaction, consider these suggestions and implement similar safety and product freshness measures as well to help maintain the quality of the products you receive.

Inside Storage

It is preferable to store growing media products inside a building with a clean, solid floor. Exposure to excessive heat and sunlight causes decay of packaging and accelerates degradation of nutrients and wetting agents in mixes. Products should be kept on shrink-wrapped and covered pallets until time of use. No product should be stored under or near chemicals such as herbicides, insecticides, disinfectants or even fertilizers. Whether liquid or dry, such chemicals can penetrate packaging and affect the contents. Growing media products should also be stored away from seed and seed products such as bird food, livestock feed, and forage or pasture seeds, which are common in warehouse and retail settings.

Outside Storage

If it is necessary to keep potting mixes, peat moss or aggregates outside, they should be stacked on pallets or a raised platform to minimize exposure to vegetation, water and soil. The stacked bales or bags should be shrink-wrapped and under an open-air roof or covered with a tarp. The goal is to eliminate direct sunlight and precipitation, yet provide ample circulation and prevention of heat build-up. Prolonged heat exposure can result in drying or hardening of growing mixes and peat moss as well as degradation of wetting agents. If not protected appropriately, water can enter loose-fill bags through the vent holes if exposed to precipitation. When growing mixes get wet in the bag, nutrients can be lost and lime is activated causing pH to rise. This leads to performance issues when the product is used.

Products stored outside should not be placed where they are subject to drift, splash or spray from chemicals used on farms, ranches, railroads, power lines, ditches, manufacturing facilities, roadways, etc. Furthermore, bales or bags kept outside are more likely to pick up drifting weed seeds that get caught in folds or stick to the packaging.

Shelf Life

Normal stock rotation practices i.e., first in/first out (FIFO) should be observed with growing media products. Ensure that your potting mix ships to you soon after being manufactured, and work with your potting mix manufacturer to be able to read and understand their dating/coding system. Ideally, all plug and propagation mixes should be used within the first six months of being manufactured. If plug and germination mixes are one year or older from the date of manufacture they should be properly disposed.

Standard potting mixes should not be stored for more than six months either. However, the usage of these mixes may be possible up to one year. If the product is older than one year according to the production code on the bag or bale, you should test the mix for wettability prior to planting.

Controlled-Release Fertilizers and Special Additives

Some growing media manufacturers offer flexibility and convenience by incorporating controlled-release fertilizers (CRF), fungicides, or other special amendments and additives into growing mixes. However, precautions apply. Please note that all controlled release fertilizers are not created equal and therefore manufacturers have specific storage guidelines when they are added to potting mixes. Most CRF manufacturers suggest that potting mixes be used within one week after manufacturing, with some exceptions. Refer to the CRF product label for specific instructions on longevity and usage of CRF incorporated potting mixes.

Incorporated biofungicides and similar products can also have a shelf life and are affected by storage conditions such as temperature, moisture and oxygen. It is important that the mix not only be used rather quickly (ideally within a few weeks; check with the manufacturer) but also be stored out of harsh conditions as noted above.

Production Codes

Most reputable mix manufacturers stamp or label their products in some manner with production codes. For example, Sunshine LC1 will have an adhesive sticker on the side of the bag or bale with a code such as E10 215, which means the product was produced at the Elma, MB facility in 2010 on the 215th day of the year. A placard is often attached to the pallet shrink-wrap with the same information. We encourage the education of all employees on how to read and understand the production codes. This will aid in maintaining FIFO practices and maximum mix performance.

In addition to producing quality products, reputable growing media, peat moss and aggregates manufacturers will perform extensive tests to assure quality. Records and samples are kept from each lot produced. Every bag or bale should have a code number and record, which should be traceable to bills of lading and/or invoices as needed. This information can be very useful if a question arises as to the quality or freshness of a product. As growers, you should also keep records of these numbers on your own invoices or production records.

This information is for your protection. Follow these guidelines to prevent damage to your profits!

Todd Cavins

Todd Cavins is technical specialist with SunGro Horticulture. He can be reached at 405.553.3751 or

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