Uses of compost in potting mixes

The ornamental horticulture industry uses a variety of materials as ingredients in growing substrates for many ornamental plants. There are many attributes that make growing substrates effective, including good aeration and drainage, availability at an acceptable price, and chemical attributes conducive for plant growth. In recent years there has been a trend in which more traditional organic components, such as Canadian sphagnum peat, have been partially replaced by an increasing array of waste-product compost. Plant response to increasing quantities of compost in the potting mix, and to different types of compost are variable. This paper reviews some important issues in the utilization of urban waste compost products.