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