We are purchasing a load of pasteurized mushroom compost from Hy-tech Farm in West Grove, Chester County to amend the soil in our flower beds. Recently we've heard from another flower farmer that mushroom compost contains herbicides. Please let us know if that is correct. Thank you
We're in luck. An extension horticulturist answered this question very well. The link to his answer is
If you can get a certificate or guarantee from Hy-tech Farm that their products are free of weed seeds, pesticides and herbicides, that will your best assurance. It is possible for herbicides to persist in hay, manure, and top soil. Before planting extensively in any purchased product that isn't certified, try planting a sample patch and see what happens. You can use bean seeds and purchased or transplanted seedlings. If the plants die or grow distorted leaves and stems, you'll know that something is wrong with the product. At the same time, the test will tell you if there are weed seeds present.