I bought a gorgeous bouquet of sunflowers and zinnias from the farmers market three Saturdays ago. By Sunday afternoon in my 78-degree kitchen, half of them had wilted so dramatically they looked like they were auditioning for a tragedy. Twelve bucks. One day. It stung.

The woman who sold them to me — a flower farmer who has been doing this for thirty years — gave me a list of tips the next time I saw her. I have been following them ever since, and my flowers now last a full week even when the house is warm. Some of this is basic, but two things surprised me.

Cut them right, right away

As soon as you get flowers home, cut the stems at a 45-degree angle under running water or submerged in a bowl of water. The angle keeps the stem from sitting flat on the bottom of the vase (which blocks water uptake), and cutting underwater prevents air bubbles from entering the stem.

Use sharp scissors or garden shears. Dull blades crush the stem instead of slicing it, which damages the xylem — the tiny tubes that pull water up to the petals. Crushed xylem equals flowers that drink poorly and wilt fast.

Re-cut the stems every two days when you change the water. Each fresh cut reopens the drinking channels.

The water matters more than you think

Warm water, not cold. Lukewarm water (about 100°F) gets absorbed faster than cold. The exception is bulb flowers like tulips and daffodils — those prefer cold water. For everything else, think warm.

Add the flower food packet that came with your bouquet. If you threw it away (I always did), mix one teaspoon of sugar, one teaspoon of bleach, and two teaspoons of lemon juice into a quart of warm water. The sugar feeds the flowers, the bleach kills bacteria, and the lemon juice acidifies the water so it flows better through the stems.

Placement is everything in summer

Keep flowers away from direct sun, air conditioning vents, and fruit bowls. Sun and AC vents both dry out petals. Fruit — especially apples and bananas — releases ethylene gas that causes flowers to age faster. The same gas that ripens avocados murders peonies.

Also, do not put flowers on top of the refrigerator. It is warm up there, which speeds up wilting, and the vibration from the compressor is apparently bad for stems. The flower farmer told me this and she was very intense about it, so I listen.

Nighttime fridge trick

If you really want to stretch them — like for a dinner party the next day — put the vase in the refrigerator overnight. Florists keep flowers in coolers for a reason. The cold slows down respiration and ethylene production. Just make sure the fridge is not so cold it freezes the petals. Remove any fruit first (see above: ethylene).