Here is the full list of all 14 Flower achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Play the game after a week long break.
Bloom 10,000 flowers.
Beyond all flowers lies another room.
Completely awaken the city.
Journey to the city unscathed.
Light a darkened pool.
Play with the windmills and ride the wind seven times.
Use the grass as your canvas and paint the ground with three different colors.
Reminisce for three minutes before returning to the room.
Release all of the names to the sky.
Take a ten minute break between any dreams.
The dream has just started...
Life could be simple...
Find and bloom a secret flower.