how do you get garden treasure cards and how are they different form normal garden cards
I have gotten a few drops in CL. Not many. They are just as you would buy from the gardening packs (I think, I haven't bought any since things went live). There are a few more higher level spells of the 'prevent pests for 48 hrs' variety I have seen.
I have gotten them from harvesting plants. I have gotten them from killing NPC's. So far they cast spells like "Prevent level x pests for n hours." I have not cast them yet as I am re-designing my garden, but I suspect they will save me a lot of pet energy when I re-start. No pests for 48 hours is a pretty big deal IF you can get everything inside the treatment ring ... ;)