Balancing the Plant 'pet'

While considering the scripts for max's work on the quest pets, I was struck by an idea.
The plant wall is generally considered a bit overpowered, so I've had a few ideas. Firstly, the nursery is just too sparse to begin with, so I figured that early in the quest it could be populated by a variety of other plants that grow from a vanilla 0/1 defender to a 0/2 defender with a basic ability over 2 upgrades. I imagine their abilities with a cost of tap<1/card.self> tap<1/creature.other> indicating another creature using part of the plant to prepare a ritual or something. Later in the game you would be able to purchase the current plant pet as I think its almost crucial against some later challenges.
My other idea is to create the sense of having to maintain the plants. Initially I thought that every X matches you would have to buy plant food or something otherwise the plant would downgrade, but that would have to be hardcoded and I want to avoid that. So I thought another solution that would work flavorwise is to have a system similar to levellers. The plant would start each game as a 0/1 defender, then at the beginning of each upkeep you put a growth counter on it. Then the abilities would be scripted as for levellers. This would mean that the final iteration of the plant (each would still be individual scripts with different level caps) would only be a 1/4 life-gaining-deathtouching-killir on turn 4 which seems far more fair. No more relying on that alone while you get your combo pieces out.
The two ideas could also be combined obviously.
Sorry about the massive post
but let me know your thoughts on the matter. I'll throw a script together in the morning to better illustrate it.

The plant wall is generally considered a bit overpowered, so I've had a few ideas. Firstly, the nursery is just too sparse to begin with, so I figured that early in the quest it could be populated by a variety of other plants that grow from a vanilla 0/1 defender to a 0/2 defender with a basic ability over 2 upgrades. I imagine their abilities with a cost of tap<1/card.self> tap<1/creature.other> indicating another creature using part of the plant to prepare a ritual or something. Later in the game you would be able to purchase the current plant pet as I think its almost crucial against some later challenges.
My other idea is to create the sense of having to maintain the plants. Initially I thought that every X matches you would have to buy plant food or something otherwise the plant would downgrade, but that would have to be hardcoded and I want to avoid that. So I thought another solution that would work flavorwise is to have a system similar to levellers. The plant would start each game as a 0/1 defender, then at the beginning of each upkeep you put a growth counter on it. Then the abilities would be scripted as for levellers. This would mean that the final iteration of the plant (each would still be individual scripts with different level caps) would only be a 1/4 life-gaining-deathtouching-killir on turn 4 which seems far more fair. No more relying on that alone while you get your combo pieces out.
The two ideas could also be combined obviously.
Sorry about the massive post
