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Miracle Gro Potting Mix Ingredients

By Aileen Clarkson ; Updated September 21, 2017
Good quality potting soil ensures happy plants.
Purple zinnia image by Marko Grgin from Fotolia.com

Scotts Miracle-Gro potting mix is an easy way to get your plants off to a good start. Because the mix contains continuous-release 21-7-14 plant food, your potted plants will be fed for up to six months. It can be used for indoor or outdoor plants. Scotts claims that this mix will give you "more blooms and more color."

Canadian Sphagnum Peat Moss

Miracle-Gro's potting mix contains 55 to 65 percent Canadian sphagnum peat moss. This partially decomposed sphagnum moss has large cell structures for absorbing air and water like a sponge. It does not contain nutrients, but absorbs added nutrients and releases them when needed. According to The Canadian Sphagnum Peat Moss Association, this means valuable nutrients are not lost through leaching.

Composted Softwood Bark

Composted softwood bark is made from Southern pine bark, fir bark and Northern softwood bark (pine, hemlock and spruce bark). The pH ranges from 4 to 6.5, depending on the combination. It is used in the potting mix to add bulk, not to retain water.

Horticultural Grade Perlite

The white granules you see in Miracle-Gro's potting mix are made by vaporizing water in the volcanic material perlite, which forms air pockets within the structure. Perlite is very light and holds moisture and nutrients, making them available to plants' roots.

Wetting Agent

Wetting agents reduce a liquid's surface tension, causing the liquid to more easily spread or penetrate. For plants, this makes it easier for the rest of the potting mix to absorb water.


Miracle-Gro's potting mix contains 0.21 percent ammonium nitrate, 0.07 percent ammonium and calcium phosphates, and 0.14 percent potassium sulfate. This all-purpose fertilizer mix is good for most annuals and perennials. The ammonium nitrate (nitrogen) helps plants produce more chlorophyll. The ammonium and calcium phosphates (phosphorus) aids in root development and boosts plants' flowering ability and bloom size. The potassium sulfate (potassium) guards a plant against diseases and increases its drought and cold tolerance.


About the Author


Aileen Clarkson has been an award-winning editor and reporter for more than 20 years, earning three awards from the Society of Professional Journalists. She has worked for several newspapers, including "The Washington Post" and "The Charlotte Observer." Clarkson earned a Bachelor of Arts in journalism from the University of Florida.