I have two intermatic corp. model ct27 heavy duty dig. timers. I use them in the summer to turn a light off and on because of heat issues. Ive never had any problems with them. work great. no idea where i got them but Im sure its a hardware store. I use analog timers too. they work fine. yeah, they might be off ten mins here or there, but that wont mess you plants up!

I would like to point one thing out. I almost burnt my house down once. best advice i can give you is no matter what you buy... make sure is a three pronged heavy duty and dont use the cheap little two prong to three adapter. Spend the extra money! I think mine were about $15.... not alot.

Intermatic Timers - Consumer Indoor Timers - Digital Timers - DT27C - Self Adjusting