These are some simple techniques you can use to extend the life of your cut flowers from days, to over a week.
1) In the morning or early evening, harvest the flowers when the buds are just starting to open.
2) Cut each stem to the desired length. Use sharp scissors to cut the stem at a slant, increasing the area for water uptake.
3) Immediately put the stem in a bucket of tepid water to prevent the cut end from sealing. If the cut end should seal, the flower would not be able to take up water.
4) Once indoors, strip off any foliage on the stems that would be underwater in your display vase, to prevent rotting leaves in the water.
5) Transfer to a vase with lukewarm water to a depth of halfway up the stems.
6) Flowers with hollow stems such as lupines, delphiniums and hollyhocks tend to dry out quickly, after which they will not take up water at all. To prevent this, invert the stems, fill with water, and plug with cotton or soft tissue. Hold the plug in position while placing each flower in the water.
7) The best-proven additive is the commercially prepared powder available from your local florist. Favorite old-fashioned water additives to preserve fresh cut flowers include: 1⁄2 cup lemon-lime soda (non-diet) or 1 tsp. sugar to provide food, and 1/4 tsp of bleach or vodka to inhibit bacteria.
8) Be sure to change water completely every 2 days. This is more important than any additive you could use!
9) Finally ... keep the vase out of direct sunlight and away from fruit (which releases ethylene gas, which encourages wilting.) Though these steps may seem like fussy tasks, the reward of longer-lasting cut flowers fresh from your garden will be well worth the effort!