Answer: If the hairspray contains a lacquer or similar ingredient, a trace of it it could damage the plant. I am not sure what the propellent is in modern hairspray, but even if it could assist plants I don't think the small amount would have any effect unless in a very tightly closed environment. I have heard of people rigging up systems for use in aquarium underwater plantings, but not for terrestrial plants. I'm sorry I can't give you a more specific answer.
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