Painting the Inside of a Planter Box

Cover the working area with a drop cloth or tarp to protect against spills, drips or overspray. It's best to work outdoors or in a well-ventilated area. Open any windows if you work inside.

Clean the planter thoroughly with warm water, dish detergent and a scrub brush or cloth. Rinse it thoroughly and let it dry completely before painting.

Remove any existing finish from the inside of wood planters with 80- or 120-grit sandpaper, and wipe off any dust with a damp cloth. Smooth it out with 220-grit sandpaper, following the direction of the wood grain, and remove the dust.

Apply an even coat of water-based primer to the inside of wood planters with a paint brush. For concrete planters, use a primer designed for concrete and masonry. Apply the primer using a back-and-forth motion. To use a spray primer on wood, plastic, metal or clay planters, select one designed for all surfaces. Spray it evenly and thoroughly to the inside of the planter using a side-to-side motion, holding the can about 12 inches away. Allow the primer to dry for at least four hours. Sand the planter lightly if the primer feels bumpy and wipe off the dust. Apply another coat. Allow it to dry for 24 hours.

Select a latex paint for wood planters, PVC-safe spray paint for plastic planters, masonry/stucco paint for concrete planters or metal spray paint for metal planters.

Paint wood planters with a paint brush, following the direction of the wood grain and using even strokes. Follow the same method of application for concrete. Allow the paint to dry thoroughly, then apply a second coat. Allow it to dry for 12 to 24 hours. Apply spray paint by shaking the can thoroughly and spraying an even coat from 12 inches away using a side-to-side motion. Allow it to dry for 1 hour, then apply another coat. Allow to dry for 24 hours.

Apply two coats of concrete sealant to concrete planters with a paint brush, allowing the paint to dry between coats for the amount of time specified on the label.