In the next version you will be able to build Stone Planters from the Workshop. For 25 Stone, you can place one of these Planters around your garden. When any seed is dropped into a planter, it will begin growing 10 flowers of that type, this makes fulfilling requirements for flowers much easier.
At any time during the growth cycle you can drop a new seed into the Planter to change the flower type, but growth will start over from the beginning for all flowers in the Planter.