By Terril A. Nell, Ph.D., AAF
Research Coordinator at the American Floral Endowment
Professor Emeritus of Floriculture at the University of Florida
Summer provides a host of seasonal cut flowers to expand the palette of flower colors and forms. Many summer flowers may be available locally, so wholesalers and retail florists are encouraged to establish relationships with local growers where products may be purchased and picked up at the farms or possibly delivered directly without shipping costs. Because freshness is so important, it’s best to obtain these flowers right after cutting rather than buying them from markets where they might have been subjected to higher temperatures and less-than-ideal conditions.
As with any cut flowers, growers may need to use special treatment solutions to avoid ethylene damage and prevent premature leaf yellowing. Retail florists should become familiar with locally grown flowers and learn the best method of optimizing vase life.
Let’s look at some of the most popular summer flowers and how to care for them.
Allium offers flowers in white and blue-purples, with flowers lasting 14 to 20 days, depending on the species. Growers should treat these flowers with an anti-ethylene product because they are sensitive to ethylene. It is best to use a holding solution (low-dose flower food) for optimum vase life. Allium is sensitive to cold temperatures and, therefore, should be held in a floral cooler at 36 F to 41 F for no more than three or four days, or their vase life will be reduced.
Celosia should be harvested when the flowers are just beginning to open. For initial hydration, plain water is fine, but it does not hold the flowers for long periods. Retail florists should use a flower food solution. Vase life may exceed two to three weeks if flower food solution is used (with or without floral foam).
Dahlia is a popular garden flower that can be harvested for use in arrangements. Today, Dahlia flowers are locally grown for the retail flower market. They may have a short vase life, so it is important to hydrate and place them into a floral cooler at 36 F to 42 F quickly after harvest. Storage should be for a short period because some research shows that refrigerated storage decreases vase life. Hydration and flower food solutions are recommended to achieve a vase life of five to 11 days.
Echinaceae (coneflower) offers a wider range of colors than most cut flowers—purple, red, pink, orange, yellow, green and white. The petals may last only four to seven days, but the cones have longer vase life. Flowers should be harvested when the petals begin to open and placed into a hydration solution and stored in a floral cooler at 36 F to 42 F. Flower food solution is recommended.
Eustoma/Lisianthus is a popular cut flower that is available in many colors, including white, pink and blue-purple, and flower forms, including single and double flowers. Growers should treat these flowers with an anti-ethylene product because they are sensitive to ethylene. Flowers are harvested with only a few flowers open, so the use of flower food is needed to promote flower opening and maintain flower color. Flowers are best held in a floral cooler at 36 F to 40 F.
Gladiolus is a traditional cut flower that may be locally grown in some locations during the summer. Breeders have developed new varieties with improved vase life and many flower color choices. Purchase Gladiolus with no more than one-third to one-half of the flower buds showing color. The use of hydration solutions and flower food is recommended to help the buds open properly. The top two or three buds can be removed to encourage the other buds to open.
Helianthus (sunflower) is now available in yellow and orange-yellow varieties that are mostly pollenless and seedless. Purchase sunflowers when a few petals have just begun to unfurl and the center disk is still firm. Leaves can be removed because they yellow quickly. Always first use a commercial hydration solution, followed by a holding solution (low-dose flower food), to lower the solution pH and reduce the microbial growth in the stems. Maintaining clean solution in storage containers and vases is critical to get the best vase life with sunflowers. Hold the flowers in a floral cooler at 36 F to 41 F.
Paeonia (peony) is a popular flower that may be locally grown or produced internationally and shipped to flower markets in the U.S. One major summer production area is Alaska. Peonies must be harvested at the proper flower stage, depending on the variety. These flowers are not ethylene sensitive. FloraLife has established that hydrating peonies with flower food or bulb-flower-specific food for 36 hours increases the vase life and bud size of all varieties tested; therefore, peonies should be held in flower food solutions in retail stores.
Viburnum (snowball) varieties offer a wide range of flower sizes, with some varieties having fragrance and colorful fruit. The variety ‘Silver Dollar’ is one of the most popular varieties for cut flowers due to its small flower size. Wholesale and retail florists should hold these flowers in commercial flower food, at 36 F to 40 F.
Zinnia is a traditional garden flower that is easily converted to use as a cut flower. Always use a commercial hydration solution first, followed by a holding solution (low-dose flower food), to lower the solution pH and reduce the microbial growth in the stems. Zinnia may produce dirty vase solutions, so maintaining clean solution in storage containers and vases is imperative. Store these flowers in a floral cooler near 40 F.
Summer flowers bring new looks to your flower designs and seasonal appeal for your customers. Get to know your local growers so that you get the freshest products, and use flower food solutions to get the best results with these flowers.
The flowers described above are just a small select group of summer flowers that are often available from “local” growers. Research reports on AFE-funded research at North Carolina State University are available on the AFE website (endowment.org/afe-research-reports-post-production-series-400).
If you are not familiar with specialty cut flower growers in your area, the Association of Specialty Cut Flower Growers (ascfg.org) offers a list of local growers and flowers available throughout the U.S. In addition, ASCFG has published a book, Postharvest Handling of Cut Flowers and Greens, that provides detailed information on more than 175 cut flowers and greens (ascfg.org/shop/books).