Flower Match
Cut out several flowers with different number of pedals on them. Have your children put them in order of number of pedals or match the ones with the same number of pedals. Additionally you can cut them out of several colors and have your children match them by color. 
Outdoor Garden
If you have the facilities make a real garden for your children in a small swimming
pool (punch holes for drainage) They will love to work it just like it's a real
flower garden.
Clear Garden
Let your children see how flowers grow sprouts and then form root systems. Wet
paper towels and put them in clear plastic cups. Finally sprinkle the flower
seeds on the paper towel until the seeds are clearly visible. Set the cups in
the sun and keep the towels moist, you will have growth in no time
Planting Flowers
Cut several (ten or more) flower shapes form construction paper or wallpaper
scraps and glue the cut outs to craft sticks. Print the numbers one through
ten on index cards. Put sand in a flower pot. Have your children draw the number
cards and then plant the number of flowers that the card indicates into the
sand.
Flowers Food
Put a white carnation in a cup of colored water (darker color the better) and
let your kids see how flowers drink water (the flower will take get its color
changed as it takes in the water)