This weekend, we made self-irrigating planters from recycled water bottles, and planted marigold seeds that I hope will germinate in time for Teacher Appreciation Week.
The Wisconsin Fast Plants program covers the basics of making this planter from recycled plastic bottles. I incorporated the helpful comments on Seattle Sundries, too. Those directions are really useful.
I started with my drill, and made many small holes on the shoulder of the water bottles. I put one larger hole in the shoulder of the water bottles and in the bottle cap. Next I used my utility knife to separate the top of the bottle from the base. I experimented with where to cut until I found what looked good to me. This completed the "adult only" portion of the craft; happily, they enjoyed watching.
I knotted two sections of cotton twine in the middle, and we poked the knot through the hole in the cap with a toothpick. The outside of the cap had four "legs" while the inside had a knot to keep from pulling through. Then the boys screwed the cap on the top of the bottle. Next we placed the top, cap down, into the bottom of the former water bottle. I handed out narrow strips of aluminum foil for the boys to line the planter. One of the comments was that roots don't like sunlight, so unless the plant is to be transplanted, the roots need to shielded. Aluminum foil was the suggestion I remembered, and, well, it's fun to shape! They put a straw over the foil and through the larger hole in the top, and used cotton twine and a small piece of duct tape to fasten the straw securely to the side. Then I scooped in potting mix. We soaked the potting mix with water, and poured out the excess water from the base. Next I cut sections of duct tape, and the boys wrapped all the way around to tape the tops to the bottoms. They put 4 seeds in each planter. To finish this (later), we will wrap the outside of the planter to minimize algae growth in the water (see last item on Fast Plants page).
I don't know how well it will work, but I added the straw to refill the water in the base so the plants can continue to self-irrigate by wicking up the cotton twine indefinitely.