Has locally grown mint been sprayed with any herbicides or pesticides? Can mint compost be safely used in an organic garden?
Benton County Oregon
Almost all mint straw compost is distributed locally. If possible, ask the source what herbicides have been used on it. Generally speaking, mint is not considered a food crop for humans, and so legally can have been sprayed with all kinds of things. I am not personally aware of incidents indicating the types of herbicides (clopyralid and chemically related materials) that survive the composting process, nor do I have any way of methodically tracking such incidents. It's always a good idea to ask your supplier. If the supplier is not the grower, he or she might not know. The direct answer to your question is: you'll have to decide for yourself. WSU offers a bioassay that would permit you to test any compost that you buy: http://puyallup.wsu.edu/soilmgmt/pubs/clobioassay.pdf.