Locate a flower shop either online or an actual shop you can walk into. Most online shops don't deliver single flowers, so instead of wasting time calling around, try a local flower store first.
Tell the florist what you are looking for and discuss any fees or store policies with him. Some stores have a minimum purchase for delivery, and others do not. Find out how much you must purchase in order for the shop to send the flower. You might get lucky and find a store with no minimum purchase.
Look around the shop for the perfect flower you want to send. Most florists have a cooler where they keep large vases full of single flowers. They use these flowers in their bouquets, but they also sell the flowers by the piece.
Find out if the florist requires the single flower to be sent adorned with baby's breath and fern. Sometimes a florist will wrap up the flower in cellophane and a ribbon. Any additional flowers or wrappings means additional cost.
Make sure to add up all additional costs so you aren't surprised by a final cost higher than expected. To send a single flower alone is probably inexpensive. Ask about different prices before finalizing your order.
Fill out a purchase order making sure to print clearly the delivery address. To send a single flower means accuracy. If there is a date and time or a particular person to receive the flower, include that information on the order. And don't forget to fill out a card so the recipient knows who the flower is from.