Many commercial greenhouses use independent laboratories to test for elements contained in plants and the various substances associated with horticulture, i.e., water, potting soil, fertilizer, etc. While laboratory analysis can greatly help in determining the cause of an African Violet's symptoms, the use of these laboratories will generally cost a couple hundred dollars.
If you are looking for a laboratory, you should find several in the yellow pages of your phone book. However, you many want to seek the advice of a local botanical garden or your county agriculture extension office. Ask them what laboratory they use.
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