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Shade gardens: soil preparation

The shady areas of a garden may seem to present the greatest challenges, but with appropriate planning, soil preparation and maintenance, these areas can become the most beautiful and usable areas in the landscape. Knowing what is achievable in the shade is key, as well as understanding the special requirements of gardening in the shade. Perennial shade garden with blooming blue selfheal (Prunella), white coral bells (Heuchera), large glossy leaves of pigsqueak (Bergenia) and heart shaped leaves of Siberian bugloss (Brunnera)

Plants that thrive in some degree of shade typically evolved as woodland species, in the shade of deciduous or coniferous forests. Along with adapting to shade, they also adapted to the light, often acid, humus soils of the forest. Most Colorado soils are mineral soils and much more alkaline than those in moist temperate forests.

For successful shade gardening, amend soil with compost or sphagnum peat moss to create the conditions preferred by most shade plants. Dig at least four inches of organic matter into the soil. Mix the organic matter at least eight inches deep into the soil.

Amending soil is important, if shade is cast by buildings or trees. Concrete foundations can contribute to dry, alkaline soils, and trees, especially those with shallow, fibrous roots, deplete the soil of moisture and nutrients. Where tree roots are a problem, add a two inch layer of organic matter and sand over the roots. Do not add more than two inches of matter over tree roots, however, or the roots below may become starved for oxygen.

Moisture is often critical to successful shade gardening, but there are several hardy shrubs and perennials that tolerate dry shade. In either case, generous soil amendment is essential for successful shade gardening.

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

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Updated Thursday, February 06, 2014