Has the sweet aroma of lilacs tempted you to cut a few twigs for the house? Lilacs and other woody flowering shrubs can be disappointing in an arrangement unless they receive special treatment before they go in the vase.
As you cut the branches, place them in water. When you get them in the house, submerge the branches up to the flower in coolish water let them sit for 30 minutes or so, this is a sort of curing step and is very important. Before putting the lilacs into the new water, strip all but the most necessary leaves, and then break the stems at the bottom. They should be split at the ends to open the capillaries so water can reach the flowers. Ideally you should cut the flowers early in the morning, as that is the best time to cut and then don’t arrange them till later in the day. When you are ready to put the branches in a vase add a tiny bit of bleach and a little sugar to the water, its best if this water is also cool.
Then just enjoy them. Add more water daily keeping the level high and change it if the water gets cloudy or smelly, but the bleach should keep this from happening. Also moving them to a cool location at night, like a back porch helps even more. Processing woody branches takes more time but it is worth it in the long run.