Here is the full list of all 23 Gnomes Garden 3: The thief of castles achievements.
For collecting all trophies
For restoring Stonehenge
For speeding up construction
For constructing a building
For completing 5 levels with 3 stars
For completing 15 levels with 3 stars
For completing all levels with 3 stars
For defeating the evil warlock
For growing your first tree
For growing your second tree
For growing your third tree
For growing your fourth tree
For growing your fifth tree
For growing your sixth tree
For growing your seventh tree
For restoring a plant
For restoring the signal fires
For getting rid of a Gremlin
For growing a lily pad
For speeding up workers
For clearing one roadblock
For stopping time
For activating an altar