Cut flowers for your flower arrangements early in the morning before heat, sun and wind dry them out. Although you can't always wait for ideal conditions, flowers collected after a period of rain last longest.
Select flowers that are almost open. The best stage of maturity for cutting depends on the type of flower, but most flowers last longest when they open in the vase.
Cut the stems on a diagonal and immediately place them in a bucket containing a few inches of warm water.
Recut the stems of your flowers 1 inch above the original cut while holding them under water. This assures that the stem doesn't have an air bubble which will prevent the uptake of water.
Seal hollow stems like those found on poppies, zinnias and most bulbs by dipping them in boiling water or holding them over a candle flame for a few seconds. This prevents the plant's store of nourishment from oozing out the stem.
Peel back an inch of bark from the end of woody stems and then lay the stem on a solid surface and hit the peeled area with a hammer. One sharp rap will do. This increases the stem's ability to take up water.
Split hard green stems on plants such as roses and other shrubby perennials while holding the plant under water. Using a sharp knife, make a vertical split from the end of the stem about 1/2 inch long.
After preparing the stem, immediately return the flowers to the bucket of water.
Remove the foliage that would otherwise be under water in the vase.
Dump the water from the bucket and add several inches of fresh water. Add a floral preservative prepared according to the package instructions.
Return the flowers to the bucket and allow them to soak in a cool, shaded location for several hours or overnight.