Maybe Aquaspikes? you fill a 1 liter or 2 liter soda bottle with water and screw the spike to the end and stick it in the pot. It drips the water down as needed.
See website below for more info.

Here is a link that might be useful: Aquaspikes

My mom has a lot of things in pots. She has mentioned putting her pots in a shallow tray with some water to get them through a few days of being gone. I have also heard of people employing kiddie pools in this same manner.

I like the soda bottle idea too! :)

How about a bucket of water with ropes stuck in the water on one end and the other in the soil. Try an experiment before you have to leave to see just how many rope "wicks" you would need per pot. Rhonda

Soak the plants, then fill some soda bottles and use a hot nail to poke holes in the screw on top. Sink the bottle into the soil. It will release the water as needed.