Automatic plant watering is now a snap and a bargain. Just screw one of these dark-green plastic water spikes onto one of your cast-off 1- or 2-liter soda-pop bottles that you've filled with water, adjust the flow-control device that's built into the screw cap, and stick the spike a couple of inches into the dirt around the potted plant. Maintains consistent moisture without over- or under-watering. Can also be used with liquid plant food! Our each is a pack of (6) water spikes.