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If you bought the "Pro-Lab" mold test kit from Lowes. Here is what the instructions say
LAB RESULTS DIRECTIONSSpecial Note: To insure that the sample stays intact during shipping, please place tape (electrical) around the edge of the petri dish and place back in the original zip-lock bag.
Here is a link to the complete instruction sheet.
If you did not by a kit made and serviced by Pro-Lab, The sample security instructions should still hold true.
Yes, tape it before transporting, shipping or mailing!
Pro-Lab has calculated all of their base-lines and median identifiers to be read assuming you do it exactly the way the instructions say to do it ie: room temp etc.
It certainly would not hurt anything to tape the dish while it grows however, you do not need to.