I would buy what ever one you think is the prettiest. As for me since I'm a flower farmer I have to go with what will last the longest. But what I do is what is recommended by Swan Island Dahlias for conditioning dahlias and that is after you just cut the stem put it in 160 F water with flower food. They say that makes them last longer. I also know dahlias really dirty the water so change it often. Cut early in the morning also. Other than that a lot of farmers use Karma dahlias for longevity. Others just go with what they like.

Happy New year.

Some dahlias have floppy stems; that is, they will not hold the bloom up nicely. If one needs nice long cutting stems, then disbudding and/or de-branching is necessary.

I have found the best cut flower dahlias for me seem to be the waterlily, poms and balls. My flower stand is outside and in the sun part of the day. I have found that most cactus and fimbriated type flowers do not hold up well to this. The really huge dahlias tend to last for fewer days but are beautiful for special occasions. Anenome and orchid types tend not to hold up as cuts though there may be some exceptions. Other then that, trial and error will show you which ones have the substance to last for 5 days. That is all I would expect from even an excellent cut flower dahlia. Its what I tell my customers.

It must be the climate differences between us, lizalily. Waterlily types just melt for me after about 5 days. I guarantee all the dahlias that I take to my customers for a week.

GrannyM, I am amazed! But I am sure different climates to have major effects. I had just not thought of the differece!
So what holds up best for you?