How long should cut flowers last in the vase? Cut-flower growers who sell at farmers' markets joke that the ideal vase life is 6 days — just long enough so the customer buys them each week. In truth, most growers aim for the longest vase life possible so customers will see their flowers as good value and come back again and again.

Here are the top 5 factors that determine vase life:

1. The variety itself. Some flowers last a day, some last 3 weeks. Even within species, there can be big differences in vase life among types and cultivars. For example, single-stem sunflowers last several days longer than branching varieties. Various products are available to increase vase life, but there is, nevertheless, a maximum longevity for every variety. The Flower Farmer lists vase life for 100 commonly grown flower varieties.
2. Stage at harvest. Most flowers can and should be picked before they are fully open, after which they continue to open in water. Picking at the optimally early stage gives the end-user a longer vase life than waiting until the flower is fully opened. Floral preservatives can help in this regard because they contain sugar, which helps sustain the flower as it continues to open and develop good color.
3. Time of day at harvest. Flowers should be picked in the morning or evening; picking during the heat of the day makes it more difficult for the flower stem to uptake water, resulting in shorter vase life.
4. Temperature and light after harvest. Flowers that are exposed to heat and direct sun after harvest will suffer. Some, though not all, can be stored in a cold cooler to prolong vase life. All will benefit from being held in an air-conditioned room, out of direct sunlight.
5. Cleanliness. Once flowers are cut, they take up water through their stems. Bacteria can clog the stems, reducing water uptake and causing them to wilt prematurely. Therefore, it is imperative to reduce the chance of bacterial contamination. Anything that touches the flowers must be extremely clean — clippers, water, buckets, vases. Scrub everything before every use with soap and bleach, and let tools dry in the sun. If stems are dirty (after a heavy rain, for example), let the soil wash off in the picking bucket, then transfer the stems to a bucket of clean solution. Floral preservatives contain a biocide that kills bacteria, and can be used if cut flowers don't last long enough.

For more in-depth information, read our article on Cut-Flower Harvesting & Post-Harvest Care • Best Practices & Wisdom from the Slow Flowers Community …