Put an aspirin tablet in the vase

put a little sugar in the water

That is what i’ve always heard too, an aspirin in the water.

For cut roses: Cut the stem at an angle before putting them in a vase.

For rooted roses: plant them as soon as possible in good well draining soil in an area where excess water can drain off, and water them often enough so that the soil is damp but not soggy.

Re-cut the stem while holding the stem in water at an angle with sharp pruner (to avoid crushing the stem). Cutting the stem while it is submerged in clean fresh water prevents air from getting into the stem (that will prevent the water from reaching the blossom).

leave them on the plant ...

you could also use a sprig of willow in cut flowers