Question about best way to water outdoors

I have some plants outside, and have a question about the best way to water them.
You can first of all consider this a guerilla grow.
We get occasional rain but not ample enough for what I want to do.
I know I could purchase some polymer to mix into the soil, but I was looking into making like a rain water catcher or something?
I've tried using the search bar, but to no avail.
I don't really feel like running out to the fuckers every few days, so anybody got any idea?
and no
no aqua globes

Water every few days... UNLESS feel someone might see u. If u dont feel really paranoid when u go to your site, why not water?

One idea is to get them out of pots and plant them in the ground, mulch them as well.

yeah if you put em into the ground they need water less, but the good thing with pots is that you can move them if you need to.
and if your going to multch make sure you dont put mulch right around the stock or it will rot it!

I've been thinking of putting them in the ground, and think I will do it next week.
I've been thinking about polymers to add to the soil, has anyone had good luck with them?