Cut flowers have a charm that makes summer sing. If you are interested in cutting blooms for arrangements, follow these tips and your blooms should look their best for a long time.
When to cut
Cut flowers early in the morning, says Mark Erickson of the Society of American Florists. If you cannot gather flowers early, your second-best choice is to cut at the end of the day when temperatures are cooler. Erickson suggests picking flowers still in the bud stage for longer-lasting arrangements. Blooms that are already open will not last nearly as long as partially opened buds.
How to cut
After you cut your flowers, bring them inside and recut them while holding the stem under warm water. This helps to avoid damaging the vascular (water-transporting) system of the plant, which acts something like a straw. If you don't recut stems under water, air bubbles can enter the flower and prevent water and nutrients from flowing up the stem.
Cut at a slight angle so more stem surface area is exposed to absorb moisture. Always use a very sharp knife or clippers because a dull tool can crush the stem tubes that carry water and nutrients.
After cutting your stems, leave the flowers in a dark spot for up to six hours. Then, says Erickson, store them in a cool place (temperatures around 35 degrees F are best, but not below freezing) until you intend to use them.
Flowers generally last longer if you add a commercial floral preservative to the water. These are generally acidic and contain sugar-like compounds, as well as a fungicide/bactericide. The sugar provides energy for the blossoms and the acidity helps keep rotting organisms from growing. (Rot will dramatically shorten the life of your flowers. To avoid this, use a clean vase for each arrangement, change the water daily, and be sure that flower foliage stays out of the water.) Keep your vase in a cool place at night to further prolong your flowers' life span, and keep arrangements out of direct sun and away from heat registers or other sources of warm, dry air.
Special situations: Sappy stems
Sappy-stemmed plants such as poppy, milkweed, balloon flower, and euphorbia need to have their stems seared immediately after cutting to keep the flowers looking good in a vase arrangement. To sear a stem, hold the end of the cut stem in a candle flame for several seconds.
For years, gardeners were told they should crush the stems of woody-stemmed plants such as butterfly bush, dogwood, and lilac to make them take up water better and last longer. New research indicates this might not be the case, according to Erickson. Instead, he recommends simply making a clean, angled cut as you would with other cut flowers.
Ethylene is a natural gas that speeds up the aging process in flowers and may darken the flower colors. Ripening fruits (such as apples) and vegetables produce ethylene. Other sources include automobile exhaust and rotting plant foliage (be sure no foliage falls below the waterline in the vase). Some of the flowers most sensitive to ethylene are said to be yarrow, agapanthus, lady's mantle, snapdragon, monkshood, lily, and delphinium.