The little sprouts, still in their original heater box get some water.
Then, after being transplanted to their new, roomier accomodations, they get some more water.
Here's our experiment in cubic closest packing, also called face-centered cubic packing (fcc). Successful cubic closest packing would have given us 7 rows of 4 per bin.
That didn't really work, because the rows stuck out too far on the sides, so we went back to body-centered cubic packing (bcc), which gave us 6 rows of 4 per bin.
(Surely only a mineralogist would think of these things.)