The high point of growing dahlias is enjoying the flowers. They may appear any time in July, depending upon the varieties and types you're growing. To use dahlias as cut flowers, cut the blossoms when they are fully open. Use sharp shears or a knife to cut a long enough stem for the use intended. Plunge the cut ends into warm water immediately. When you're ready to arrange the flowers, cut off about1/4inch of the stem base and place the stems in warm water. Be sure to use a sharp knife or shears. Using floral preservatives or changing the water every 2-3 days will increase the life of cut flowers. Another useful technique is to place the basal inch of each stem in boiling water for 1 minute while shielding the leaves and upper stem and flowers from the steam and heat.