The 2 litre bottle holder, a set of 4 for $20, looks pretty snazzy. I suppose you'd just have to keep track for a while of exactly how much water you're giving them however often, and then adjust accordingly.

Predicated that you have proper drainage and that the temperatures and lighting isn't fluctuating all that much, this should work pretty well I'd think, especially for those of us who go on vacation.
darpin Reviewed by darpin on . Automatic Watering Systems I'm still debating about this. I might buy one just to check it out. I really like the one that does the soil humidity detection for you, and then applies water at a constant rate. So it's never overdone or underdone. Regardless though, here's the links I found in case anyone else is curious: http://www.gardeners.com/Shopping/sell.asp?ProdGroupID=17104&DeptPGID=19694&lstCategory=0&RecGroupNum=2 Rating: 5