What you do in the first few minutes at home makes a real difference to how fresh flowers settle in. You do not need special kit. A clean vase, a sharp knife or pair of secateurs, and fresh water will do.
Unwrap gently
Take off the paper and ties while holding the bunch near the base, so the heads do not knock together. Have the vase ready before you start. Cut stems seal up when they sit out of water, so the aim is to get them drinking again quickly.
Start with a clean vase
Bacteria in a dirty vase cloud the water and cause stems to rot. Wash the vase in hot, soapy water, using a bottle brush for narrow necks, and rinse it well. Fill it about three-quarters full.
Recut every stem
Use a sharp knife or secateurs. Blunt blades crush the stem and make it harder for water to travel up it. Take a little off the end of each stem, around a centimetre or two, with a clean, angled cut and no jagged edges. The angle exposes more of the stem to the water. Put each stem into the vase as soon as it is cut.
Strip the lower leaves
Remove any leaves that would sit below the waterline. Leaves left underwater rot, discolour the water and feed the bacteria that clog stems.
Add the flower food
If your bouquet came with a sachet, stir it into the water, following the instructions on the packet. Cut-flower food gives the flowers sugars to feed on and contains an antibacterial agent to help keep the water clean.
Choose a cool spot
Find a place out of direct sunlight and away from radiators, fires and draughts. Keep the vase away from the fruit bowl too. Ripening fruit gives off ethylene gas, which can stop buds opening, dull petal colour and shorten the life of the flowers.
A note on tulips
Tulips behave a little differently. Their stems keep growing after they are cut, and over a few days some may stand noticeably taller than the rest. They also bend toward the light. Give the vase a quarter turn each day to keep the stems more upright, and if a few grow taller than you like, lift them out and trim them shorter. A stem that has curved tends to stay curved, so turning early helps.
Keep it fresh
Every two to four days, lift the flowers out, wash the vase, refill it with fresh water and flower food, and recut the stems. Top up the water in between, because a full vase drinks faster than you might expect. Take out any blooms as they fade, along with leaves that have dropped into the water, and the rest of the arrangement will stay clean and bright for longer.