Tall wedding vases or stands need to be designed as separate units,with the floral arrangement being attached to it's base at the venue. Trying to deliver totally assembled vases risks arrangements toppling over, breaking tall flower stems (or the vase!) or having the arrangements slosh out water or having the mechanics come apart in the delivery vehicle.
As a professional wedding designer for many years, I always preferred to design in silver containers, which disguise the green foam in the bowl. Silver always reflects light, so any glimpse of the bottom of the arrangement has a clean finish viewed by seated guests at the reception tables. I like to attach flat bottomed containers (clean and dry) to the top of the vase surface (also clean and dry). Rim the vase with a new strip of white floral clay. With the stand still on the floor, lift the floral arrangement up and position it over the center of the stand and push down firmly onto the clay lining the lip of the stand.
Fresh floral clay has a strong grip and it must be twisted hard later to remove the flowers and container later. Floral clay holds strong and with a tight seal, even with water or dampness is splashed on it. I recommend the steel bowls because the combination of fresh flowers and wet florist foam is HEAVY!
Keep in mind that the arrangement must be balanced. That means a heavy stand and a wide base to support a fresh flower arrangement. I normally use a large table mirror to stabilize the arrangement. Before attaching the flower container to the stand, place a few rolled balls of clay under the foot of the stand. Then press the stand firmly, attaching it to the table mirror with clay. This is the secret that gives the arrangement a wider support base that in turn keeps tall wedding vases from toppling over!
You have to think ahead for the whole package - including plans for the design, the assembly, delivery and setting up of the tall arrangements once you arrive on site. You need the stand, the steel container, a large block of foam, fresh floral clay, waterproof tape and a large table mirror.
Tower vases are popular because that's what brides see the most, but I actually prefer the heavy metal candle stands because they are more solid and usually screw apart for easy shipping and storage. The metal stands don't have the danger of breakage and are generally more sturdy on the tables. Check out the ones below that come in sets and are actually more affordable than you think!
Keep all your delivery boxes. This makes the vases or candle stands easy to re-pack and sell on E-bay or to a local bride after your own event is over. I did this for both my daughter's weddings and actually ended up MAKING money on the designs. Be sure to take good pictures with the flowers on the table and the tall wedding vases will sell themselves after the wedding is over.
For tall glass vases, I still use shallow, rounded steel bowls (with lips that lay on the mouth of the vase. Read carefully and be sure you order the correct size bowl to fit on the top of the vase! Again, design in the containers at home, then transport vases and arrangements separately, transport, then rim the top lip of the vase with fresh floral clay and lift the steel bowl up, setting it onto the vase that is on the floor, and press down hard, sealing the silver bowl to the top of the vase. Rounded silver bowls look better in the clear vases than the flat bottomed bowls used on candle stands.
Another (cheaper) option is to use clear acrylic dishes that are slightly larger than the vase mouth to hold your arrangement. Just be sure the greenery dips down to conceal the green foam in the container at the top of the vase.