Field of sunflowers growing against a blue sky with white clouds. - Thing Nong Nont/Getty Images Giants among flowers, sunflowers (Helianthus annuus) can grow up to 12 feet tall. Their round heads ...

A bouquet of cut sunflowers can easily brighten up a room. However, most sunflower bouquets will only last a short time in a vase before they begin to wilt. That is, unless you know how to correctly ...