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