Edible flowers should ideally be harvested in the cool, morning hours. If you're not going to be using the flowers immediately, cut them with the stems intact and keep them in water. You could also store them in damp paper towels in the refrigerator.
Make sure your container has drainage holes; cover the holes with a pottery shard or a piece of landscape fabric.
Use a good potting soil; we used Miracle-Gro Organic Choice.
Add a time-released fertilizer such as Scotts Osmocote Multi-Purpose Plant Food to the potting soil.
Pot your plants into the container and water thoroughly.
Place it in a spot that has a good amount of sunlight.