Question
Gina how are you thanks for helping me the last time.I am going to be getting 800.00 fresh roses and greenery on tuesday of next week, what can I do to preserve the flowers and also have the bud open up quickly I am going to be using them in an event on saturday to make floral arrangments for the event. how many roses would make a very large and tall arrangment and how many would be good for a very low arrangment.thanks so much for your help

Answer
Conditioning flowers when you get them in from the wholesaler is imperative to their success!  

With roses, you want to remove them from the grower bulk wrap and remove the thorns and foliage from the lower two thirds of the stem.  

Make a clean angled cut on each stem and submerge the stem right up to the base of the bloom in cool water.  

Keep the roses like that in a cool dark place for the first 24 hours.  

After the first twenty four hours, remove the roses, make another clean cut and submerge halfway up the stem into room temperature water with a floral preservative powder added.

This is the "finished" conditioned roses that you would see in the floral shops for retail.

As to the number of roses, "large" is subjective; I've made huge table arrangements using 6 to 9 roses along with a lot of other materials and I have made relatively small ones using more than a dozen with no other material.  Worry about the scale and balance of your piece rather than the number of blooms!  If you allow yourself 9 roses per arrangement and have greens you should be fine.