A K-Cup is a single-serve coffee maker (Keurig) contraption made of plastic. I hate plastic. It looks like this on the bottom after you make your coffee (nice little cutting-hole already started for you):

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The narrower bottom is about 1 and 3/8's inch in diameter and the top is 2 inches. If you tear off the top, you see there is this funky little coffee filter glued into it. If you cut a little circle out of the bottom,

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you see that the filter stops about a half inch from the plastic bottom:

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and, using a perfectly sized cookie cutter I just happen to have on hand, I made my rafts:

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I stuck the K Cups into the holes just far enough so I could see the water kiss the bottom of the filter and left it floating on the water to see if it would wick up the sides of the filter; it did. I used a meat tray at first to see how it would float (for seed-starting purposes), and it worked great:

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Using little sharp scissors, I clipped an X in the bottom of each K Cup filter; my thinking is that I'll use these little cups for seed germination and if the seed germinates well, the roots will eventually push through the filter with a little help from that X. And I'm also thinking that I won't have to transplant, that the ones that put out good strong viable seedlings can be left to grow right through the K Cup and put roots down into the water. To which I'll add nutrients when it's time.

So, anyway, I put vermiculite (my favorite seed-starting stuff) in the cups and planted a lettuce seed at the center of each (some arugula and mache, too). So this is what my setup looks like right now:

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I've got the water level low right now because all I'm doing is germinating seeds in just water. I need to have my air pump/air stone stituation covered by the time they're growing, though, so please see my question at K-Cup Hydroponics Part I.

Once I have actual lettuce plants growing, that's what will be in those four bins; seeds I can start in meat trays on the top and just transfer them to the rafts as appropriate.

That bit of shiny stuff in the back is one of those auto sun-shades you can pick up at the dollar store for next to nothing. I figure I may get some more and sew a little shelf-covering thing, maybe with a roll-up front, maybe not, just if I get ambitious and want to do it. Or just clip two on the back and one on each side to reflect the light around.

There may be a problem with vermiculite dropping down into the solution. I figure, though, based on the leaf lettuces I've bought in the grocery store, that the size of these is going to be about right. They will serve as a plastic collar to help hold the lettuce leaves upright and allow me to switch things in and out quickly if something dies or needs to move into the kitchen window.

I mean, heck, if you can do this, I figure the lettuce can handle growing through that collar:

Square watermelon

You'll see from my setup that I've got a warm and a cool fluorescent. That's because I got the Dual Spectrum II set from Stealth Hydro and that's what was included with it.

I guess I'll see which bulb does the best with greens and go from there when they burn out. I just hope they aren't hurt by being on an X10 appliance module controlled by Active Home Pro software....

Any thoughts? Caveats?