Some growers I know keep Physan-20 diluted in spray bottles throughout their greenhouses and use as needed. As a new in home grower I was wondering if it lasted very long so I e-mailed the company.
They told me that diluted, it is potent for 3 to 5 DAYS.
I guess I need to make it up as I go and in as small a quantity that I can reasonably measure.
I suspect the same is true of a number of concentrates.
"A word to the wise..."
Nick