I would search for "painting rain barrel"

....Scuff plastic surface....Latex Primer....Latex Paint

A recent discussion on the Florida forum has an outstanding example:

Here is a link that might be useful: Paint rain barrel Florida forum

Not sure how to paint them, but here's what it would look like blue. White is nice, maybe you could get the stains out.

Krylon fusion works well, and so do Rustoleum products labeled for plastic. Price points are the same. Both brands have "plastic primer" that allows you to use other paints after they've dried. I prefer Rustoleum. I've spray painted many huge black plastic nursery pots. The problem is, by the time you finish painting, the cost advantage of using plastic barrels or plastic nursery containers starts to drop.

Rustoleum also has a brush on plastic primer, but very few retailers carry it. It is available online (Amazon). I'm skeptical that it's more cost effective than their spray paint though. I'm not sure if Krylon carries a similar product.

Frankly, I've been happier with the results I've gotten by wrapping the outside of the planters with the sunscreen shadecloth used for patios (90%). It makes a skirt of sorts, kind of like a christmas tree skirt. I've used burlap too, but it doesn't last more than one season.

Thanks for the responses about painting rainbarrels - the one in the link looks fantastic but would take more artistic ability than I have. Greentiger could you post an image of your planters wrapped with the shadecloth? Thanks.

There was an easy idea recently using white lattice wrapped around pots. Can't find the photo, but the blog on the link has the same idea for compost. If the barrel is too stained, lattice can be found in different colors. You might find a color to go with your bricks. Some small fencing products can be wrapped around pots.

If the pots aren't going to be moved around, you can just stack bricks around them in a basketweave or other pattern.

The shade cloth also sounds like a good idea.

Linda

Here is a link that might be useful: white lattice