Sugar will only speed the decay of delphinium or any other cut flower unless you also add a little bit of bleach and some lemon juice. Use commercial floral food instead. Here is an article about extending the life of cut flowers. https://www.mastergardeners.org/picks/extendlife.html
I am a certified floral designer and a Master Gardener. I would never use straight sugar in my arrangements.
Sugar will only speed the decay of delphinium or any other cut flower unless you also add a little bit of bleach and some lemon juice. Use commercial floral food instead. Here is an article about extending the life of cut flowers. https://www.mastergardeners.org/picks/extendlife.html
I am a certified floral designer and a Master Gardener. I would never use straight sugar in my arrangements.