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