Is the stat debuff permanent like the ability? If so I would suggest making both spells permanents so it's more obvious, plus it adds balance since the opponent can get rid of it.
The card names seem a tad off after the changes, an ensnaring forest should have a much larger debuff then scrub or shrub or w/e but the larger debuff causes balance issues. Perhaps the upgrade should be restraining brush or something? Plants of similar size to scrubs/shrubs logically have comparable debuffs but the quantity allows it to affect all the opponent's creatures.
Other than that, I think it's an interesting card, spreads ability control to another element at least.