Planters are a staple of the potter’s repertoire, but it’s hard to make a planter that works better than the standard red earthenware flower pot! However, certain plants benefit from special pots made with their needs in mind. Recently I’ve seen hand-made African violet planters for sale featuring an inner pot that you plant the violet in, which sits in an outer pot that’s filled with water. This way you can water the plant from below without getting water on their sensitive leaves. The theory is that the inner pot is porous so water can soak through it from the outer pot—the reverse of using a porous olla inside a planter to provide a steady supply of water to the plants around it. However, if you use the same clay for both the inner and outer pots, you’re going to face a problem. Let’s say you use stoneware and fire to maturity. The inner pot won’t be porous, since stoneware that’s fired to maturity becomes vitrified, or non-porous. If you use earthenware clay, or fire your stoneware to a lower temperature, the inner pot will be porous, but so will the outer pot. It will leave a wet patch on any surface it sits on and ruin your floor or furniture. You can’t count on glazing the outer pot to keep it from leaking, as any slight crazing in the glaze will cause it to leak, and over time you can expect the glaze to craze anyway. You could fire the inner pot to a lower temperature and fire the outer pot to vitrification, but then the two pots will shrink at different rates and getting them to fit together nicely will be tricky—not impossible, but tricky. You’ll face the same problem if you use earthenware clay for the inner pot and stoneware for the outer pot. I have a simpler solution: pierce the inner pot to allow water to seep in.
Choosing the Size of Your Pot
You can make these pots in any size, from the size of a mug up to a gallon or so. The ones I’ve seen tend to be tiny, for freshly propagated plants, but a pot that will fit a mature plant seems more useful. For a moderate-sized planter, use 2 pounds of clay for each pot. You’ll make the inner pot first.
Center one lump of clay and open it up, leaving a ¼-inch thick floor. There’s no need for a foot on this planter, so you don’t want to leave the bottom thick. Create a flat floor about 4 inches across and pull the wall up, allowing it to flare slightly. Once you have all the clay pulled up into the wall, use a soft rib to push the top inch of the rim out a bit wider, creating a ledge at least ¼ inch wide that can rest on the rim of the outer pot (1). The wider you make this ledge, the easier it will be to make the outer pot fit. At this point the pot should look exactly like the classic earthenware flower pot. Use calipers to measure the diameter of the pot right below the ledge you just created (2). The inner edge of the rim of the outer pot should match this measurement. Measure the height of the inner pot up to the ledge—the outer pot has to be taller than this measurement. Once I’ve made these measurements, I like to flute the rim of the inner pot, to make it look flowery and distinctively different than the classic version (3). If I do this, I use a rib on it to make sure I didn’t distort the pot in the process. Now, run a wire under the pot to separate it from the wheel.
Throwing the Second Pot
Use the second lump of clay to throw the outer pot. This pot will be a rounder bowl form, to make sure there is room for water around the inner pot. Center the clay and open it up, again leaving a ¼-inch thick floor that is about 4 inches in diameter. Bring the walls up in a gentle curve, making sure it ends up at least as tall as the inner pot. When you reach the height you need, check the diameter inside the rim with the calipers (4). The diameter inside the rim needs to be fairly close to the caliper measurement on the inner pot, or the inner pot may just drop through and sit on the floor of the outer pot instead of perching on the rim. Run a wire under the pot to release it from the bat.
As soon as you can pick them up without distorting them (5), try nesting the pieces together. If the fit isn’t perfect, you may be able to trim a bit from one or the other pot. Trim any excess weight from the base of each pot, without trimming a foot.
When the outer pot has stiffened up a bit, you need to make two little spouts, like little pouty lower lips, just below the rim. These spouts allow you to put water in the pot without lifting the inner pot out.
To make the spouts, put the pot back on the wheel and use a needle tool to draw a line all the way around, an inch or so below the rim. Now use a decorating disk to make two marks opposite each other on this line (6). Cut a slit about 1½ inches wide at each mark. Now push the lower edges of these slits gently outward (7), using a moistened finger and pressing from the inside. Keep stretching the clay until you have two triangular lips wide enough to accommodate the spout of a watering can. Why do you want two spouts? Partly for symmetry, but it also allows you to stick a finger into one spout while you pour water into the other, so you can feel when the water level is right. Sponge the spout area smooth and refine the spout shapes before moving on.
The last step is piercing the inner pot so water can seep into it from the outer pot. When it’s leather hard, turn it over and use a decorating disk to mark out a pattern of holes on the bottom and sides of the pot (8). I make 8 very small holes on the bottom and another 8 just above the base of the pot, but I’m sure the exact number of holes isn’t important. As long as the plants roots can soak up water when they need it, they’ll be happy. Dry the pieces together so they don’t warp (9).
After they’ve been bisque fired, glaze the interior and exterior of the outer pot, for beauty and ease of cleaning. You only need to glaze the rim of the inner pot as the rest of it won’t be visible and you don’t want to risk filling in the tiny holes with glaze. If they fit tightly together, you should fire the two pieces together. Be sure to wax the rim of the outer pot first.
Time to Plant
To use your planter, plant an African violet in the inner pot, preferably using African Violet potting mix. Put the two pots together, then fill the outer pot through one spout while watching or feeling for the water level to rise in the other spout. If you water it this way once a week or so, your violet should do very well.
Sumi von Dassow is an artist, instructor, and regular contributor to Pottery Making Illustrated. She lives in Golden, Colorado. Check out Sumi’s book, In the Potter’s Kitchen, available in the Ceramic Arts Network Shop, http://ceramicartsnetwork.org/store/in-the-potters-kitchen.