Ideally flowers should be cut in the early morning or early evening when their stalks show maximum water retention. Heat is anyway stressful for the plants and they will wither sooner if cut in midday. Tactfully enquire from one of the guys working at the florist about the time when they usually cut the flowers. The answer will give you an indication of the freshness.
You can also note the kind of instrument the florist uses to trim the edges of the flowers. Scissors should never be used as they damage the water channels. The correct choice is a sharpened knife. Knowing that the florist uses the correct instrument will tell you that the quality of flowers from the shop is also likely to be good.
It’s best to order in season blooms as they will be far less expensive. Ask your florist to get you luxuriant local blooms that go well with the colour scheme and the overall theme of your event. Each stylist will have their own discounts on the flowers of the month
If the event is an outdoor one then ask your florist whether water can be drawn inside the petals even if the stem is cut. Make a list of such flowers and make sure that they are placed at any event where no regular watering is possible. These kinds of flowers are apt to last longer. Apart from this ordering in lots of off season blooms is very taxing to the environment and upsets the delicate balance of nature.
References: Finding The Right Affordable Photo Booth