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