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