You ought to be able to blast many aphids off with a fine, hard spray of water. I've read that very few (or none) will climb back up onto the plant.
A friend had an aphid infestation outside (on lupines). He took a few days to think about it, then checked them again.
The aphids were gone, but there were lots of ladybugs, fat from having presumably dined on aphids.
Good luck!
