Store growing media properly to avoid production problems

Improperly stored growing media can become contaminated with weed seeds, insects or chemicals. Media properties including pH and soluble salts could be altered so that they are too high at time of planting. The media could become very dry and hard so that it is difficult to wet.
Univ. of Mass. extension floriculture specialist Tina Smith said media should be stored in a cool, dry, low-light environment. If possible, store media inside a building (not a greenhouse) with a clean floor.
Bagged media exposed to heat and sunlight can cause packaging to break down resulting in degradation of nutrients and wetting agents. Keep packaged media shrink-wrapped and covered on pallets until it is used. Do not store media near pesticides or fertilizers that could cause contamination.
Bagged media stored outdoors should be stacked on pallets or raised off the ground. Keep the bags shrink-wrapped and covered with a tarp or placed under cover protected from direct sunlight and water. Unprotected bagged mixes with vent holes can become wet, loose nutrients and result in lime being activated resulting in high pH.
Media stored in direct sunlight can develop slime where condensate forms. Slime mold may also form on the medium surface soon after potting. This mold is not harmful to plants and usually goes away on its own. High temperatures can result in drying and hardening of peat moss and degradation of wetting agents.
Inventory media so that earliest shipments are used first. Plug, propagation and standard mixes should be used within the first six months of being manufactured. Soil test media stored for six months or longer and check wettability.

Pictured: Keep packaged media shrink-wrapped and covered on pallets until it is used.