An olla is an unglazed clay pot, buried in the ground, filled with water. Water seeps through the clay pot into the surrounding soil. A simple DIY is to use an unglazed flowerpot and saucer. Flatten a small ball of putty over both sides of the drain hole in the flowerpot. Bury the pot right side up between two plants. Fill the pot with water and use the saucer as a cover. For container plants,…