Round dishes can fit together like hexagons, with extra room at the intersection of any 3.
That's where I was thinking to plant, but plants growing out the middle of a plate would look very neat and tidy!
Plus it gives another opportunity for planting at exactly half the distance.
It will also keep the plates from pooling water.
Plates are designed to stack, but the stack would probably collect water without a center hole.
Stick a terracotta pot underneath and you have a reservoir.
Glass plates are tricky,I think.
Probably better to leave them undrilled, inverted and used to warm the soil in the spring.
Maybe skip them entirely as other items do the job better.
I'm liking plates more and more!
My next trip to the reuse center I plan to grab seed starting trays to use as mulch in my pumpkin and watermelon beds.
Eventually these plants will shade the soil themselves, but right now it's either apply mulch or weed often.
So far I've been weeding, but stacking seed starting and soil protection appeals to me.
I was thinking beans, because the seed is so cheap, but now I'm thinking fall greens, because they like shade and are less likely to get tangled with the vines.