This is a self-watering container for growing most plants. Just fill the reservoir with water and it will be wicked up through soil-filled columns to your plants' roots. In theory, it should maintain the optimum moisture in the soil, save water, and make container gardening (indoors and out) really low-maintainance. I haven't done any fancy layered fertilizer stuff, but supposedly if you put a layer of fertilizer down first, before the dirt, the water will bring up a constant flow of nutrients to the plants and so no more fertilizer worries.
This project is inspired by another:
But mine has no PVC!
-a storage bin of any size (if it's clear like mine you can see water level, but the light might encourage algae!)
-cheap potting mix (don't use anything fancy or water might not wick well!)
-hose or tube (but PVC leaches toxins into soil!)
-Sturdy plastic cups, and some less sturdy soda bottles
-Heavy black garbage bag (watch out for added rat-deterrent chemicals and stuff)
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Step 1: Make the Shelf and Main Support/wicking Columns
First, cut around the container's lid to make a "shelf" for the dirt. Try to get it so it will be close against the sides of the container once it's in there. See picture. Then drill holes in it to drain the water.
Then take 2 of your sturdy plastic cups and cut the bottoms off, making tubes. You can use any non-toxic tube-shaped object for this.
Next, drill two holes like so in shelf. Make sure they're a little smaller than the cups, so that the cups can hold up the shelf.
Then drill a hole for the hose or tube where you will pour water for the reservoir. I could have made this hole under the shelf on the side of the container, but it doesn't really matter.
Step 2: Completing the Shelf and Supports
Drill several holes in the 2 sturdy cups to allow water in. Make two of these holes close to the top, then attach the cups to the shelf with wire ties.
Now cut some soda bottles to the height of the shelf. Keep in mind that weight may warp the bottom of the container, and you'll have to compensate for that. The soda bottles will support the corners and center of the shelf. Actually, you can use sturdy plastic cups for this too, which will make the thing more robust, but I couldn't spare any more cups. Attach them to the shelf as you did the sturdy cups, and drill holes in them to allow water to move through. In my version, these bottles don't actually have anything to do with wicking, they just hold up the shelf.
When everything is in place and seems sturdy, duct tape around the edge of the shelf so that dirt won't fall through the gap between the shelf and the wall of the container.
Make sure to drill an overflow hole about an inch below the shelf. You might want to drill several to promote air circulation.
Step 3: Fill With Dirt, Water, and Plants!
Remember, use a cheap potting mix. You can try using a layer of fertilizer put down first right on the shelf, tell me if it works out! Get it really packed into the rigid cups, and get that soil soaking wet to make sure there are no air bubbles there.
Make sure to have the container where you want it to sit before filling the water reservoir, or it will be crazy heavy.
I planted coffee plants, and tea, stevia, and jalapeno seeds in here, I'll post the results in a few weeks.
Make sure to put a black garbage bag over the top once your plants are big enough to peek over the surface of it. Cut X's in it for the plants to poke through, and use what's left of the lid to secure the bag. This will conserve water, keep the soil more moist, and maybe keep things a little warmer.
You can be cool like me and add a grow light. I'm going to experiment with LEDs in the future, and you should too, since they're awesome.
Good luck, and I hope you've enjoyed my first instructable!
-Does anyone think an aquarium airstone and pump in the reservoir would make a difference?
-Also, if a hydroponic medium if used in place of dirt, do you think this setup would make a good wicking system? What mediums would wick enough to do this? I've heard that using a rope wick leads to clogging and crystallization and suspect that this wouldn't be as much as an issue if the wick was two 3-inch columns of the medium itself.