I was cutting up some soda bottles for another Replayground project and wondering what to do with the top half I was about to discard, when I remembered that it would make a great drip irrigation system for my thirsty houseplants.
I've been using this technique ever since I first read about it on You Grow Girl a few years ago. Cut the bottom off your soda bottle and drill a couple of very small holes in the cap. After the bottle's wedged into the soil and filled with water, these small holes will allow water to drip slowly down to the plant's roots.
It's a gentle watering system for more delicate plants or seedlings, and does a great job of getting water down to roots where it's needed (especially in summer when water just evaporates off the top of the soil).
It felt great to avoid throwing more plastic in the trash and give my plants a little TLC at the same time!