Always use clean vases and clean water. This inhibits bacterial growth, which can block the capillaries in the stem. You can wash your vases with chlorinated cleaners.

Place flowers in water immediately after cutting the stems. At the cut surface, a wound response is induced which can block the capillaries again within as little as 1 minute when exposed to air. Roses are especially sensitive to cavitation(air bubbles in the stem) caused by cutting. It is best to cut roses under water. It is best to cut the stems at an angle with a very sharp knife or purpose built under water cutter.

Hard (alkaline) water generally reduces vase life. If your area has hard water, use a deionizer or some citric acid. Too much sodium (Na) in the water is toxic for carnations and roses. Fluoride (F) is very toxic for Gerbera, Gladiolus and Freesia. Never underestimate the effect that different water characteristics can have on flowers. European flower handlers have complete water conditioning systems, which alter the characteristics to provide the purest water possible.

Sometimes the use of warm water is recommended. However, this can be very damaging to some species. The use of hot water is ALWAYS damaging. Never place dry, cold flowers in warm water. Always let the flowers warm up a bit first.

In most cases, the addition of cut-flower preservative gives substantial improvement to both the vase life and flowering. This is partly the result of the food supply, but also because these additives inhibit bacterial growth and delay senescence. Worldwide available preservatives are from Pokon & Chrysal or Floralife. A quality florist will always provide this with a purchase. Some cut-flower species require special preservatives.

Avoid major temperature differences when you bring your flowers home. Especially in winter, the flowers will benefit when they can adjust for several hours in a cool (15 C, 60 F) place.

Never leave flowers in a closed car, in the sun, or in places that are too hot. Avoid extended periods of warm dry transport. Too much dehydration will induce air bubbles in the stem capillaries (a process known as cavitation) which will block any further water uptake in the stem.

Similarly, avoid exposure to freezing temperatures. Some flowers will die in seconds at these temperatures.

Most cut-flower species have had a pre-treatment directly after harvest. This treatment is usually mandatory before auction and gives a substantial quality improvement for the consumers. It is based on extensive scientific research in The Netherlands. The treatment may cause some discoloration at the bottom of the stems. This is nothing to worry about.