LOL nice...?
The main problem, from a production standpoint, is that all these cards would have to:
1.) exist (for all intensive purposes in this post, we will assume this is true)
2.) be up for purchase in the bazaar or be a rare. I could probably see Seed, Plant, Tree, Desert Tree, and Mangrove all for purchase in the bazaar, with the other three as rares. Or just Seed and Plant in the bazaar with the other six as rares.
As for the upgraded versions of these cards? I would probably make the purchasable cards either cost less or have more health. The upper level cards are powerful already, and making them cost less wouldn't have much of an effect aside from having to recast them if they get RT'd. I would probably make their abilities cost less, from four quanta to three.