Plastic flowers are great for outdoor use because the material is naturally waterproof and durable. You can buy artificial daisies at Walmart for under $18 for a bunch of eight. They're a generous ball of flowers. They come in five colors (fuchsia, orange-red, purple, white, and yellow) and are UV-resistant. If you plan to hang the ball somewhere outside but want it protected from the weather, if you're making it for a special occasion, or if you don't mind taking it down every time you come inside, buy a fancier fake flower. Get romantic with pink and cream silk peony flowers. You can buy them at Hobby Lobby for about $9 a bunch. (They also come in lots of other pretty colors.)
Can I use fresh flowers? Unless you can find flowers with very sturdy stems, it will be difficult to use fresh flowers. Plus, the bouquets won't last long, and the styrofoam balls inside can't be reused once holes are poked. You can use dried flowers, though. The stems are strong, and the flowers will last just as long as plastic in the right conditions. You may need to poke holes with a bamboo skewer and use glue beforehand (more on this later). This is a great idea for anyone who wants to reduce the amount of plastic they use in this project. You can buy flowers, or you can save money by learning how to dry and style your favorite flowers from your garden.