BG,

The real problem for automation especially when you go away for an extended time is that if the system malfunctions and doesn't turn off what damage can be done. Best to have a dedicated friend water while you are away. There are simple battery powered timers that hook up to a hose and drip line with pressure regulator. Time it to deliver the minimal water you need for your seedlings. Any hardware or garden store can help you with the details. Viola. JMHO Aloha

An irrigation timer could do the trick. Depending on how long you are gone, you may want someone to check and make sure it's working properly. The last thing you want is to come home to burst tubing and a huge water bill.

Here is a link that might be useful: irrigation timers