Do you have a trusted friend you could have water them for you? If not, I'd go with the light suggestion stinky mentioned or your pump idea. They will most likely need watered a couple times during that 10 day period. If nothing else, buy a pump and timer and just keep the recepit and return them after you get back and say they broke or something. No one is going to question returned items with recepit after only 10 days. If they ask, just say you were using the stuff for your garden pond and something fucked up. Good luck!