A simulated patina helps faux-clay plastic pots blend in with those made from real terra-cotta. The best candidates for artificial weathering are those with many nooks and crannies, such as this basket-weave planter. You will need acrylic paint in white, lime green, and moss green.
With a bristle brush, lightly paint white around the top of the pot and moss green around the bottom, leaving a narrow space between the two. Dampen a sponge with water, and use it to apply the lime green to the pot's midsection, overlapping the other colors.
Once the pot has dried, sand with rough-textured sandpaper (about 60 to 70 grit), paying special attention to edges.