After you buy the heavenly upgrade Cosmic Beginner's Luck (CBL)
and have a level 9 garden (36 plots).
1. Ascend and don't buy the Heavenly Chip Secret upgrade.
-It should start in the vault.
2. Get the dragon aura Mind Over Matter.
3. Get Santa's Bottomless Bag upgrade from Christmas season.
Optional: Get the Dragon Teddy Bear upgrade from petting Krumblor.
With CBL, MOM, and SBB:
You will have a +535% chance at each plant drop!