You can't forget Papaver Somniferum. No flower garden is complete without it! ;^)
/sarc
Red rose shining in the sun
Rosa alba white as snow,
Gillyflowers pink and white
Thus will my sweet garden grow.
Johnny jumpups in the spring,
Sunflower in the summer sun,
Daylilies stretched out in a line,
Thus will my sweet garden run.
Crabapple blossoms in the spring,
Red fruit shining in the snow,
as my roses sleep till spring
Thus will my sweet garden go.