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Science-based gardening information for Colorado communities from CSU Extension, Denver Botanic Gardens, and Green Industries of Colorado.

1601 – Epsom Salts & Wood Ashes   arrow

Colorado soils are very different than the soils found on both coasts and in the Midwest. Improving the drainage, aeration and water holding characteristics of Colorado soils is more important than fertilizing because, if the soil structure is poor, plants won’t grow, regardless of fertilizer. When it is necessary to fertilize, there are some points to keep in mind.

Front Range soils are mostly alkaline or basic. Some mountain soils are acid in nature, more like soils in the eastern states. A pH soil test, can confirm how basic or acidic soil is.

Eastern Colorado soils are generally acidic and are low in Epsom salts, or magnesium sulfate. It can be added to promote healthier plants.

In alkaline Colorado soils, magnesium is highly available to plants so adding Epsom salts is not necessary. Wood ashes are alkaline and contain salts high in potassium. In eastern acid soils that lack potassium, or “potash,” throwing wood ashes in the garden is an excellent fertilization practice.

For more information, see the following Colorado State University Extension fact sheet(s).

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