Cut cotton fabric into strips about 1 inch wide and 12 inches to 18 inches long. The length of the strip depends on how large your plant pot is and how far away you must place the water source. Use only 100 percent cotton fabric as blends won't wick the moisture as well.
Bury one end of a fabric strip in the soil near the stem of your houseplant. Wrap the strip gently around the stem once, just to hold it in place.
Lay the other end of the strip over the edge of the plant pot. Place a large bowl near the plant pot. Place the other end of the strip into the bowl.
Fill the bowl with warm water. Watch the cotton strip. The fabric will soak up water, bringing it from the bowl to the dry fabric along the strip. The dry fabric fibers will eventually draw moisture all along its length to the end and into the soil around your plant. As long as the soil around the wick is dry, the wick will continue to draw moisture in a continuous amount.