What Is in Miracle-Gro Moisture Control Potting Mix?

Homemade Mixes

• Homemade potting soil includes peat moss, well-rotted compost or manure, leaf mold, sand and occasionally plain backyard dirt in varying percentages, depending on personal recipes. Other ingredients for homemade mixes include lime, rock phosphate and greensand for pH balance, phosphorus, potassium and soil conditioners. Vermiculite and perlite are inert soil conditioners. Both are silicon-based minerals produced using heat to expand their volumes. Vermiculite absorbs more water than perlite, which is added primarily for aeration. No matter what recipe, all homemade potting soils share one characteristic: they must be sterilized using heat. Greenhouse keepers may heat soil on large hot plates for days, but home gardeners must bake small batches in their kitchen ovens. Commercially prepared potting soils provide a sterile finished product for home gardeners.

Miracle-Gro's History

• The company that formulated the water-soluble garden fertilizer in the familiar green box was founded in 1951 and merged with the Scotts company, makers of lawn products and slow-release fertilizer called Osmocote, formulated for houseplants and home gardens. Today, Scotts Miracle-Gro Company (SMG) is a worldwide marketer of lawn-care products and equipment including a range of potting soils for gardeners. Miracle-Gro Moisture Control Potting Soil contains a sterile soil-less mixture, materials to retain moisture and Osmocote.

Media

• SMG's basic mix contains between 50 and 60 percent sphagnum peat moss. The remaining mass is composed of coconut bark fibers, known as core pith and composted small bits of pine bark, called bark fines. The resulting medium is sterile, light and easy to use in containers. Perlite is added to maintain aeration and avoid compaction of the peat. The perlite also produces some crystalline silicate dust, but the dust comprises less than 1 percent of the total weight of the product.

Nutrients

• Unlike many commercial potting soils, Miracle-Gro Moisture Control Potting Soil contains fertilizer. The package warns against adding fertilizer when planting to avoid fertilizer burn and identifies Osmacote as the fertilizer source. Fertilizer appears as translucent small pellets in the mix and dissolves over a period of six weeks. Formulation of the fertilizer as listed on packaging is .12 percent ammoniacal nitrogen, .09 percent nitrate nitrogen, .07 percent available phosphate, .14 percent soluble potassium oxide and .10 percent water-soluble iron. The remaining weight of the fertilizer pellets consists of coating for portions of the nitrogen and phosphates to ensure slow-release and other inert matter.