How to Drill a Hole In a Clay Pot

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Experienced gardeners know that proper drainage is essential to maintaining the root health of plants. Some pots come with drainage holes in the bottom or on the sides. Clay pots are often sold without drainage holes, which can affect the health and vitality of your container garden. Follow these instructions to easily add a drainage hole to a clay pot.

Drilling Drainage Holes in Clay Pots

Clay is a naturally occurring, soft, and earthy material. When mixed with appropriate amounts of water, it becomes moldable. High heat is used to bake molded clay, producing a strong and durable piece of clay pottery.  Glazes can be added before the firing process to enhance the durability or beauty of the pottery.

Clay pots drying in the sun

Terracotta is a popular red clay, often used to create flowerpots. Root systems of most plants will rot if exposed to excess water.

  • Gardeners appreciate terracotta pots for their porousness, which allows excess water to escape. 
  • The rate at which the water leaves the pot is determined by how much water can get through the clay.
  • Adding a drainage hole ensures that the water doesn’t stand in the pot long enough to rot the roots. 

Every pot can benefit from at least one drainage hole in the center of the pot’s bottom. Larger plants often thrive with three drainage holes, placed at equal intervals. Do some research into your plant and your climate to determine how many holes you need to drill, where they should be placed, and how big they should be. 

¼” is the size often recommended for pots that will be filled with loose soil. If your growing medium contains bark or perlite, you may want to add more holes or make them slightly larger. These materials can obstruct small holes and prevent proper drainage. 

Clay Pot Hole-Drilling Instructions

  1. Determine if the pot is glazed or unglazed. Glazed pots will have a shiny and smooth surface, and are non-porous. Unglazed pots are dull, rough to the touch, and highly porous. The process for drilling unglazed posts is similar to drilling through brick.
  2. If unglazed, submerge your pot in water and allow it to soak overnight. Clay is porous, so the water will penetrate throughout the clay pot.  It is easier to drill through a wet clay pot than a dry one, because water both cools and lubricates the tip of your bit. If you don’t have time to soak the pot overnight, try to leave it in for at least one hour. This will speed up the drilling process because you won’t need to take as many cool-down breaks. You can skip this step for glazed pots. Set the pot in a dish rack to drip dry. 
  3. Prepare your drilling surface. Choose a study table or bench and protect it by spreading newspaper or a cardboard box over the surface. Set the pot bottom-up on your work surface. Drilling clay releases silica into the air, and inhaling silica is linked with cancer, so always use a respirator. Eye protection such as goggles or safety glasses is recommended. 
  4. Place a few strips of masking or painters tape in an X shape over the area you intend to drill. The tape makes it easier for the drill to enter the clay without slipping. It also helps prevent damage to the pot, such as chipping. Once you drill through the tape you can remove it immediately or wait until the hole is finished.
  5. Measure and mark the hole or holes to be drilled. To avoid damaging the structure of the pot, all holes should be at least one inch from the edge and two inches from any other hole. Use a permanent marker or pencil directly on the underside of the pot or painters tape. You could also use a nail to scratch or dent the pot’s surface. Ideally, a dent or small groove will help guide the drill bit into the clay. 
Hand holding drill bits
  1. Select an appropriate bit. For an unglazed clay pot, choose a masonry bit with a carbide trip. For a glazed clay pot, start with a bit designed for tile or glass, and then switch to a masonry bit once you’ve cleared the shiny varnish. The first bit you use should be three to four times smaller than the diameter of the finished hole. Drilling a pilot hole in clay avoids subjecting the material to too much stress, thereby reducing the risk that your pot will break. 
  2. Connect your drill to power and attach the bit. Choose a low speed setting if using a variable-speed drill, and put the drill in forward mode. Grasp the drill like a handgun, and place the tip of the drill bit against the surface of the pot. The bit of the drill should be perpendicular to the bottom of the pot. Hold the drill firmly in place. Squeeze the trigger to start drilling. Provide bracing and resistance, not pressure. 
  3. If the pot or drill starts to smoke, take a break and soak the pot again to cool it down. Drilling through clay is a slow process, requiring a lot of patience. If you have a cordless (battery-operated) drill, you can dip the tip into a cup of water to cool it down periodically while you drill. If your drill is connected to electricity via a power cord, don’t bring it anywhere near standing water due to the risk of electrocution. In this case, remove your drill bit to put it in water.
  4. Once the pilot hole has been drilled, you are ready to enlarge the hole. Choose a slightly larger drill bit and repeat steps six and seven. If your drill bit gets dull, either change it out or sharpen the drill bit. Continue this pattern with successively larger bits until the hole is the desired size. Disconnect the drill, remove the bits, and store them.  Clean up your work area using a dustpan and brush or a vacuum.

Conclusion

Maintaining plant health starts with adequate drainage. Drainage holes can be added to glazed or unglazed clay pots with minimal materials and limited effort. This project is suitable for DIYers of all experience levels. You will need an electric or battery operated handheld drill and a selection of carbide-tipped masonry bits. Overheating is the main complication to avoid.

Ellenkate grew up on job sites run by her family’s construction company. She earned her theater degree from The Hartt School, a prestigious performing arts conservatory in Connecticut. Her design and DIY work from her Chicago loft was featured in the Chicago Reader and on Apartment Therapy.