Some of my fondest childhood memories are of times I went to the farmers' market with my family, when they let me bring home a bouquet of sunflowers. I've continued this tradition into adulthood by keeping fresh-cut flowers around my home -- sometimes sunflowers, but oftentimes whatever beautiful bundles the local farmers' market down the street happens to be selling.But even after years of buying flowers weekly, I still get sad when the petals start to wither and brown and drop. Whether you bought flowers for yourself at the local supermarket, or you received a special bouquet in honor of a celebration or milestone, you'll want to extend the life of those flowers for as long as possible. This story is part of Try This, CNET's collection of simple tips to improve your life, fast. I talked with two floral experts to round up tips for buying the freshest flowers and how to keep those blooms lasting longer. I'll also share common myths that horticulturists say don't work. (For more tips, here's the best location for your plants, and here's the best indoor plants for low light and clean air.) What to look for in cut flowers Upgrade your inbox Get cnet insider From talking fridges to iPhones, our experts are here to help make the world a little less complicated. You're in the store, ready to purchase flowers for yourself or a special someone, but which bouquet should you pick from the dozens on the stand? Believe it or not, this decision can impact the longevity of the flowers you buy.Joe Guggia, owner of JP Designs Floral based in Santa Maria, California, has worked for over 45 years in the floral industry. He told me many floral bunches are shipped from Ecuador or California, so it's important to closely examine each stem and leaf to make sure you're not buying flowers that are older or were damaged during shipping. @cnetdotcom Do these 3 things to make your #flowers last longer. #trythis #lifehack #motherday #flowertok #flowerhacks #tipsandtricks original sound - madonna Next, once you pull the bushel from the display, check to make sure the water is clean and the leaves aren't yellow, spotted or drooping. You'll also want to be sure the stems aren't slimy or broken. Lucy Bradley, a consumer and community horticulture professor at North Carolina State University, told me you need to check for fuzzy gray mold and drooping, damaged petals."Extend the vase life by selecting flowers that are just beginning to open," Bradley said. "For roses and other single flowers, select blooms that have only one petal unfurled. For gladiolus and other spike flowers, choose stems with only the first two or three flowers open. For daisy-type flowers, like sunflowers, select flowers with centers that are still greenish." Your in-store buying decisions can impact the longevity of your bouquet. Tom Werner/Getty ImagesCut-flower tips that will actually workWhile there's a slew of myths surrounding flower care, Guggia and Bradley broke down some tricks that are guaranteed to work.Change the water -- and do it oftenAdding fresh, lukewarm water to a clean vase is a sure-fire way of keeping flowers healthy longer."That's the key for people who get vase arrangements, is to replace the water as frequently as they can," Guggia said. "If they just hold the whole bunch out, pour the water out and put fresh water in, and put the arrangement back in that'll keep them days and days and days."Why? Bradley explained that simply dumping out water will get rid of any bacteria growing in the vase water, which may clog the flower stem, preventing water uptake.Trim the endsGuggia and Bradley both agreed that recutting the stems of the bunches as soon as you bring them home is key for longevity. But don't even think about reaching for those blunt kitchen scissors!Bradley said the best practice is to grab a sharp knife or shears for trimming flowers to prevent damaging the stem and reducing its ability to take up water. Wipe the tool off with alcohol first and then carefully make fresh cuts on all stems at a 45-degree angle at least half an inch from the end of the stem.Cutting at an angle results in most of the base of the stem being off the bottom of the vase. It removes clogged tissue that no longer transports water to the flower, Bradley said. Be sure to trim the ends of the stems before putting flowers into a vase. Photo and Co/Getty ImagesAdd pennies, but take note of its ageYou've probably heard of the penny method or maybe you've already tried tossing a penny into your vase with the water and flowers. But before you go digging around in the bottom of your purse or jean pocket, you need to know that only pennies minted before 1982 will work. Those are the ones with the natural antimicrobial properties, which come from the copper."Originally pennies contained copper, which is a fungicide that prevents disease," Bradley said. "However, pennies are now made of mostly zinc, so are no longer effective."Some cut-flower tips don't really workWhen it comes to flower care, there will also be debate over which methods do and don't work. Maybe you've tried some in the past -- no judgment here! That said, the experts I spoke with broke down some of the biggest myths when it comes to keeping cut flowers fresher longer.Add sugar to the flower vase?If you paid attention through a high school science class, then you may remember flowers benefit from the sugars produced through photosynthesis. But this mostly applies when the flower or leaves are still attached to the plant, so think twice before dumping an entire Sprite into your vase water. While sugar can work to extend the life of cut flowers, those little packets of floral preservatives work much better. BloomsyBoxBradley explained that sometimes adding a teaspoon and a half of sugar per quart of water or using half water and half carbonated lemon-lime drink in the vase water can act as plant food to extend the bloom, but none are as effective as a commercial floral preservative.Floral preservatives are those little packets that often come with your floral arrangement. They often contain sucrose and a biocide -- an antibacterial agent -- that gives the flower energy, helps the stems absorb more water and prevents bacteria from growing.Does bleach help flowers stay fresher?As the saying goes, a little goes a long way when it comes to bleach. Bradley explained that a few drops of bleach (1 teaspoon per gallon of water) can help kill bacteria and fungi, but adding too much -- which is all too easy -- will also serve to kill plant cells.Can vodka, vinegar or aspirin extend the life of your blooms?There are many, many tricks on the internet about how to keep cut flowers longer involving vinegar, aspirin, vodka -- you name it. And while these methods may work on a case-by-case basis, our experts don't recommend these tricks since they're based on anecdotal evidence rather than backed by science. Clean water is key to prolonging to life of your floral arrangement. David Watsky/CNET"Truthfully, I wouldn't do any of those things because in most cases the arrangement is going to be a mixture of types of flowers, which may be susceptible to not accepting whatever that item is that you're putting in the water," Guggia said. "Keeping the water clean is the best thing."More tips for you:FAQs Why shouldn't I put vodka, aspirin, vinegar or other substances in the mixture I give to my flowers? While vodka, aspirin and vinegar might help prevent certain flowers from wilting away, many bouquets are composed of several different types of flowers. What works to keep one type of flower alive could harm or kill other flowers, so you'll either need to research the mixture's effect on each flower or keep it out of the bouquet. Should I put sugar into the vase with my fresh-cut flowers? While adding some sugar to the water you use for your plants can help promote their health and keep them alive, it doesn't do much for plants cut from the stem. You could try adding sugar to supplement the other tips -- but don't expect it to do very much for the bouquet.