So I looked at Lum berries on Bulbapedia and noticed that they are supremely good pokeblock material. I'm guessing that we're using the version without any Sweet (so no speed in those pokeblocks), but I think I know why our resident poffin brewer was as excited as she was about finding this.

Which brings up a question, I suppose. We'll want lots of these. So which kind of mulch would be better to pick up for them? Growth or boost is what I'm thinking, to either churn out crops faster or make the crops bigger, but I'm not sure which one to go for in this situation...