Here is the full list of all 18 Grow Up achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Complete all challenges
Complete the game 100%
Unlock all Telerouters
Take a Critter to the moon
Complete a challenge holding a Critter
Throw 100 seeds whilst gliding
Collect all crystals
Flower all STARPLANTS
Ride two Sporchids simultaneously for 400m
Plant 10 Champolines on top of each other
Discover the bull and the sheep
Discover letter block P
Blast a Critter 100m
Bounce on a Youch 7 times without touching the ground
Orbit the entire planet in BALL mode
Rescue MOM
Unlock all seeds
Visit all biomes