No; non-Nature spells besides the standard auto-includes are useful but not required for every Druid strategy.
Raptor Vine, Vine Tree, Druid's Leaf Ring, Tanglevine, Acid Ball, Surging Wave, Bloodspine Wall, Tarok, Galador, and Thornlasher make a good base.
Dragonscale Hauberk, Renewing Rain, Tarok, Galador, Acid Ball, ...
I still have 2x Power Strike in my Druid book.