Notes:

I actually don't see it as much of a plothole. As the part-time residence of a Diamond, Pink's garden would have been heavily fortified, like Camp David. Such fortifications would have naturally have a Rejuvenator to handle renegade gems; and given Gem distrust of organics, having a large amount of bio-poison on hand also makes sense, in case the plant life of the Garden ever got corrupted by a hostile alien presence. Think of it as the biggest jug of Round-up in the Universe…