Just tried using clematis in a vase this year. All of them lasted over a week . . . just snipped them and put in water. Gillian Blades, Blue Ravine, Harlow Carr, Betty Corning, Huldine and another one that might be Niobe are the ones I used. Have some new ones blooming now so I'll see how they do.

To make any cut flowers last longer bleach your vases out between uses and change the water daily. Give the stems a fresh cut with a sharp knife daily too. Scissors and pruners smash the cells that take up water. Don't hammer woody stems either despite what Martha says, she is giving very old advice.

Using commercial floral preservatives at the directed strength will be beneficial but folk remedies such as aspirin and seven up aren't.

Commercial floral preservatives contain anti bacterial ingredients and nutrients but in the wrong ratio to water they can be worse than not using at all. Many florists still don't know this and don't measure properly and are actually hastening the death of the flowers they sell.

Sad but true.

(I was a florist for over twenty years and unlike many I actually read my trade publications and attended seminars and paid attention the information coming out of the Ohio State University and Flower Council of Holland)