I had a few extra kiddos at my house this past weekend, so I enlisted them to help me set up the experiment. Needless to say, it's not a perfect setup, but it's okay.
Here is the setup:
I mixed one part vermiculite with 2 parts potting soil. We placed 3 rocks over the opening of each bottle top, with a paper towel strip hanging through the spout (not ideal, but I thought we could see if it's a cheap alternative to a piece of cotton fabric).
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1) Radish seeds only
2) Garlic cloves only (3 total)
3) Garlic clove in center of container, with radish seeds surrounding it.
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Radish seeds growing in 2 days:
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Radish seeds - day 4; no, i'm not measuring them, even though I should. I was thinking dry weights, although I forgot to measure before planting. (smh)
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All 3 treatments at 5 days post planting. 2 of the 3 garlic cloves in the "alone" bottle are starting to grow, but I don't see any garlic movement among the radishes. I even poked around in the soil a little bit. 
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