What type of paint would I use to paint concrete planters?

I would use Acrylic paint when it drys it becomes very hard . I would also spray a clear acrylic glase over it.

check with your local paint shop/hardware store- some concrete paints will waterproof your planter, but i'm not sure if they are safe for plants or not.

Use "Dry Lok" it's made specially for concret. They make an oil and latex base

I used vinyl wrap, available from any "buy it" website. Use multiple coats of any drylock product to get a smooth surface(multiple coats). The variety of colors and patterns in the vinyl is amazing. I used it on plastic containers and it still looks good in its second year. It will not be permanent but should last a few years. By that time you may be ready to change it out. Just peel it off.

I've worked on my home for the last year+ and something was just not right. Those concrete stairs were the first thing I saw when looking at the house. Last week I used a concrete dye from Home Depot to cut the gray. The color came out a little pink, but the stairs are 100 times better than they were. Now they just fade into the background.

MASONARY PAINT

Priming

Before painting concrete plant pots, you must apply a latex primer to the surface of the pots. The latex primer prevents the paint used on the surface of the plant pots from seeping in through the concrete to the soil inside, which may be detrimental to plant health and growth. Apply spray primer or brush primer on with a paintbrush, allow the primer to dry and add a second coat of primer, allowing it to dry fully before painting.

Masonry Spray Paints

If you want to spray paint a concrete plant pot, make sure you choose a spray paint labeled for masonry, which adheres to the concrete more effectively than standard spray paints. Do not spray paint the concrete plant pots while they have plants inside of them. To paint, turn the pots upside down on a covered surface, hold the spray can 8 to 12 inches from the pots and spray in an even coat.

Cement Floor Paint

Any type of paint labeled for masonry or cement can be used on the outer surface of a concrete plant pot once the pot has been primed. Many of these paints are labeled as floor paints, but should also list individual surfaces on which the paint is effective. Brush cement paints onto the exterior of the plant pots using a paintbrush, and allow the first coat to dry fully to see how the color turns out. If the color appears too light, add additional layers of paint as needed.

Seal the Plant Pots

When you finish painting a concrete plant pot with either masonry or spray paint, apply a coat of sealer to the exterior of the pots. Sealer creates a waterproof exterior to lock the paint in and prevent the release of water through the planter. Make sure the planter has drainage at the bottom though, or you may water log the plant, which can lead to mildew and root rot.