Could some of you pros tell me exactly how the flower head on a zinnia should look when I cut it? Is there a best time for doing this? Or, as long as the flower still looks good it's okay to cut? What does an old flower look like? What about vase life? Are any of you seeing 7 days on the zinnias? One more question: Do you have suggestions for preservatives in the water in the cutting buckets? These flowers are for my market. Thanks for your help.