Do they need upgrades?

It's desirable. Dancing with the Wind will provide you with very decent defense, and you can divide the High Druids (or regular Druids if you don't have High Druids) into several stacks and attack with lightning (when dividing, the total damage is higher + the enemy also often divides + this increases the likelihood that at least some of the Druids will defeat the enemy). And most importantly, survive until you get Ents; then it will be easier, especially if you actually get regeneration in your castle.