Herself’s Houseplants

Buying:
Single stem flowers should have blooms fully open. ( asters, calendulas, chrysanthemums etc )
Branching flowers should just be starting to open. ( roses etc )

Cutting:
Cut early morning for best cut flowers and immediately put into a bucket of water
Blooms that have not yet begun to open often won’t once cut

Containers:
Should be clean
Fill with warm water
Place in a cool room away from direct sunlight

Prep:
Remove leaves that will be under water
Cut the bottom inch off of each stem

Water:
I just add 1 tsp of vinegar
A more common recipe is: ( 1 tsp sugar, 1 tsp bleach, 2 tsps lemon or lime juice, 1 quart warm water )

More information:
Cut-Flower Care: How to make Your Fresh-Cut Flowers Last
The Kindest Cut

Thanks for the image!