Use an acrylic paint and a clear outdoor sealer on them.
Use glow-in-the-dark paint and they will light up your path at night!
@Amandakayesnana That is an excellent idea. Thank you
I would use a glass and ceramic paint, the kind you put in the oven and bake for 30 minutes. The large orange, light peach, and purple rocks have been painted with FolkArt Enamels, by Plaid.
I've painted rocks. I started with a primer like latex Kilz. I used exterior latex house paints. I only bought a few colors; black, white, the primary colors, red, blue, and yellow, plus green. Make sure that they are water based and intended for outdoor use. Remember to wash,clean, and dry your rocks before you paint them. I painted flower borbers and stepping stones, baskets of flowers out of retaining wall stones, and a 'Gator' flower bed. I got my ideas from a book I bought. Last summer, I tore it all up because I couldn't take care of it because of my physicical disability and Ididn't have any help or support from my husband. I put it at the curbside and everthing found a home. Have fun. I did. In fact, the 'gactor' sat by our koi pond until we got rid of the pond. I've had a wonderful time "landscaping" until I was unable, too.
I have painted dozens of rocks for the garden and sold lots, too. The most durable paint I've used is Patio Paint acrylic latex by DecoArt. I see other manufacturers now have outdoor craft paint as well. I use four or five coats of clear acrylic spray sealer and refresh it every year for the rocks in my own yard. This is a raccoon I painted over 15 years ago for my mom and dad. Spray sealer every year keeps this guy looking good. I used Patio Paint. Also, in their yard he is not sitting directly in the dirt but is on a layer of pebbles.
The book suggested DecoArt Patio Paint. It is an acrylic with a sealer, but comes in two ounce bottles. What I suggested is what the book recommened for large outdoor pieces. I used the latex exterior paints because my peices were large.