Drilling drainage holes in ceramic planters can prevent rot in decorative plants.
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Use a standard steel bit and electric drill to bore holes in plastic, tin and aluminum plant containers.
Drill holes in the bottom of the container at least ¼-inch in diameter for proper drainage.
Use a carbide bit for drilling masonry to bore holes in the bottom of unglazed plant containers. These include the distinctive terra-cotta clay pots available at nurseries and garden centers.
Buy a ceramic-tile drill bit or a bit specifically designed for cutting glass to drill holes in glazed and ceramic planters. The specialty bits are available at hardware stores.
Apply layers of masking tape close to the spot where the hole will be drilled in a ceramic or glazed planter. A few layers of tape around the target helps hold the drill bit steady and reduces the chance of a slip, which could crack or chip the planter.
Position the drill bit over the target for the hole and begin drilling, applying only enough pressure with the drill to hold the spinning bit in place. Too much pressure could crack the pot.
Take your time. Pause every few minutes to allow the drill bit to cool. This will prolong the life of the bit.
Clean away the chips and powder from drilling the planter as your work progresses.
Pour a small amount of water on the drill bit and the hole while drilling to act as a lubricant and prevent overheating, which could shatter or crack the plant container.