Ingenious Terra Cotta Watering Cones

The hand-shaped cone has a round place at the top to take screw-on plastic bottle tops of the usual size. Make a couple of holes in this, screw it on to a full bottle of water and push this into the recess in the cone. Stick the cone and the bottle into the ground (make sure the earth is damp); the water in the bottle will then drip steadily into the cone until the terra cotta is soaked through and the moisture seeps through the porous surface into the surrounding soil. It will continue to do this until a balance has been reached: that is, the dryer the soil, the more water runs from the cone; when it’s moist enough, the process temporarily ceases. The bottle acts both as a reservoir and as an indicator of when a refill is needed.

Link - Via Book Of Joe