Compost: This is fine. No matter if you go the minions route or not, everyone using this character should be forced to use uproot. It damages towers outside of their range. Though I would argue your points are best spent somewhere else. But for the uproot/shambler folk, this ability should definitely be used
Mulch/Shamblers: Fine how they are if you believe minions are worthwhile.
Open/Close: Open has all her good abilities, close has shield and +10 m/sec regen, with a small boost to hp regen, armor and aoe damage. You should be closed while you are picking at creeps, open to take out players
Spike Wave: Key skill for taking out players. She doesn't have stun, she has this. It slows them down enough so you can keep picking at them while they run away. This combined with spikes drops their armor to 0 or close to, giving you full damage on your ranged attacks.
This character is, as is, overly powerful. The ability to take out waves of creeps with 1 ability, lvl 1 bramble shield gives 700 free health, she has a slow and a way to remove your opponents armor.. not even taking into account she has the ability to take out towers, while being out of the tower's damage range. What more do you want, a big hat? Sure she wants mana items. The +1040 mana +10 m/sec regen helm is her key item. you get that and you are set. Get her the boots if you wanna have even more of an advantage with her range and spike wave. Only takes a few kills to get her items and then you can pump all your gold into the citadel.
if you play her and use minions, you are on your own.