It's also the simplest.
Start with an empty gallon plastic milk jug.. Poke a hole in the bottom near one of the corners (I use a thumbtack). That corner goes closest to the root ball. Then fill with water (add soluble fertilizer when you want it). The cap just lays on the open top to keep trash out, don't screw it down.
It will leak slowly over the course of a day, keeping your squash hydrated, even in the heat. You could probably use for other plants too.
Recycle the jugs at the end of the season, and start with new ones next year!
