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