Growing Cut Flowers Year Round

August 20, 2007 - 07:15

Who decided to have Valentine’s Day in February? Obviously, it was not a cut flower grower since growing flowers in the dead of winter is a daunting task. Many of the winter and early spring flowers available for sale were grown outside this country, but U.S. growers have a few tricks up their sleeve for year-round cut flower production.

 

The Structures

Obviously, the best and most common way to produce cut flowers year round is in a fully heated greenhouse. Smaller flower growers often don’t want to invest in these structures, so they use other options: Hoophouses, high tunnels and cold frames are all what grower Bob Ambrose, Ridgeview Acres Farm, Stahls-town, Pa., calls “protected growing structures.” They have no heat or some supplemental heat, rarely any cooling system other than roll-up sides, and are short or tall depending on the crop.

Protected growing structures offer season extension and crop protection. Season extension includes everything from forcing bulbs out of season to producing cut flowers in winter to eliminating frost damage from late-maturing crops in fall. Early and late flowers demand higher prices. Unheated or minimally heated hoophouses provide a month’s jump on planting and harvesting in spring and another month in fall to get those last-minute flowers cut.

While we usually interpret crop protection as protection from late-spring frosts, it also includes heavy winds, rain and hail. All this protection equals a big plus for cut flowers. Stems grow taller in protected structures, partly because of their sheltered environment but also because of reduced light transmission. Shade cloth is more easily placed over a greenhouse or hoophouse than in the field, which causes further elongation of stems. Support structures may be easier to set up in a protected structure as well. Quality is also improved, since it is easier to control insects, diseases, wind damage and the other “ne’er-do-wells” that plague cut flowers.

 

Turn Down The Heat

Rather than leave a hoophouse completely to the elements, several growers choose to add some heat. Even a little heat goes a long way. In work conducted in Oklahoma, John Dole, North Carolina State University, and grower Vicki Stamback, Bear Creek Farms, Stillwater, Okla., experimented with keeping night temperatures between 35 and 55° F for cool spring crops such as lupines and stock. They concluded that 40° F gave them the best of both worlds: They saved fuel and produced excellent quality flowers without slowing down growth too much.

Eliot Coleman, Four Season Farm in Harborside, Maine, grows vegetables in Zone 5, and believes he gets two zones of protection by using floating row covers inside an unheated low tunnel. Researchers at the University of Arkansas found this system worked for cut snapdragons. In the study, they pulled floating row covers over the plants on nights forecast to drop below 32° F, which happened only eight times during their Zone 6 winter.

 

Christmas Holidays

The holiday season is the busiest sales period for most retailers, and cut flowers make great gifts. Cut poinsettias have been around for a few years but few consumers are familiar with them. Ecke Ranch developed the cultivars ‘Renaissance Red’ and ‘Renaissance White’ especially for cut flower production. At North Carolina State University and the University of New Hampshire, plants were grown in 8-inch azalea pots and were ready for sale by the first week of December. Plants produced 20 to 24-inch stems in 20 weeks. Cut poinsettias must be grown in a heated greenhouse, since they cannot take temperatures lower than 50° F during the production phase. They can also be grown in ground beds.

Cut poinsettias have a terrific vase life of three weeks. Stems are still a novelty item and look best in mixed arrangements. They are often combined with white and green for holiday bouquets.

 

Valentine’s Day

Is there any flower more perfect for Valentine’s Day than bleeding hearts? In research conducted at the University of Nebraska by Ingrid Mallberg and Laurie Hodges, pre-chilled bleeding heart crowns were planted in January and given 35° F nights and 65° F days. Red bleeding hearts grew well in 1-gal. containers filled with a standard potting mix and produced two or three high-quality stems their first year when given 63-percent shade. White bleeding hearts produced an average of seven stems when grown in 5-gal. plants with no shade. The harvest period lasted 5-6 weeks. Vase life for bleeding hearts is also excellent: Red flowers lasted 12 days and white flowers lasted 17 days. Later plantings could yield flowers for Mother’s Day and June weddings.

Although there are pink cut poinsettias, the market has yet to accept them for Valentine’s Day. But one major February crop is tulips, which can be grown without any soil at all. Grower Tom Wikstrom, Happy Trowels Farm in Ogden, Utah, produces hydroponic tulips from pre-chilled bulbs. These are placed in plastic trays that allow nutrient water circulation throughout. They are grown for 2-4 weeks at 40° F before being moved into a warm greenhouse. Harvest is simple: The bulb is pulled out of the tray when it is ready. Flowers are cleaner and earlier than those grown in soil or soilless mix.

 

Spring And Summer Annuals

Grower Joe Caputi of Charlotte’s Garden in Louisa, Va., gets a month’s head start on springtime flowers with his two hoophouses. They are unheated with a single layer of poly, with plants growing directly in the ground. He grows tulips, ranunculus, anemone, sweet peas, poppies, larkspur, bupleurum and sweet William. This provides him with early spring flowers so he can have a good diversity for early markets. But the fun doesn’t stop there.

Caputi double crops his hoophouses in summer, planting annuals such as zinnias, ageratum, sunflowers and celosia. He is able to plant these 2-3 weeks earlier than the same species in the field.

 

Isn’t It Crate?

Lilies are great moneymakers for cut flower growers, and they attract customers like no other crop. Lilies are easy to grow in plastic bulb crates. There are two sizes of crates: 14½ x 22 x 8 inches (small) and 25½ x 15½ x 10 inches (large). Either can be used, although large crates are preferred for lilies (small crates are great for tulips and other smaller bulbs).

Producing lilies in bulb crates is easier than field production for several reasons. Weeds are not an issue, and water, fertility, temperature and drainage are easy to control. Crates can be moved around, placed on benches or pallets, and it’s easy to keep track of staggered plantings. Maryland grower Dave Dowling, Farmhouse Flowers and Plants, Brookeville, Md., produces all his lilies in crates, planting between 15 and 18 bulbs in each. He wouldn’t be able to grow lilies otherwise, since he has limited space.

In research conducted at the University of Maryland, Stanton Gill used a crate system and planted bulbs as early as mid-February in heated greenhouses. He says planting in early August provides growers with harvests late enough to catch Thanksgiving and even Christmas shoppers. Crofton Sloan and Susan Harkness at Mississippi State University produced Oriental, Asiatic and hybrid lilies in Zone 8 in crates in unheated hoophouses. They were able to plant in late March and harvest the first week of June.

Numerous bulbs are well adapted to the crate system. Ornithogalum or Arabian star flower can be planted in October for Easter sales. It’s a great crop for a cool greenhouse, since plants produce excellent quality flowers and 3- to 4-ft. stems when given 50° F night temperatures and day temperatures below 75° F.

Grower Harry Wilfong, Wilfong Greenhouses, Newton, N.C., produces lilies, snapdragons and callas in containers. He plants four lilies or snaps in a 6-inch standard pot. Support netting is added as required. Callas grow in 2- to 3-gal. pots placed on extruded metal benches. Plants are large, but if one contracts Erwinia, it can be quickly extracted.

 

Well Grounded

Crates are great space-savers, and bulbs often fit well into this scheme. But many growers see a decrease in quality when plants are crate grown. This is also a big problem for hydroponic tulip growers.

Stamback produces most of her greenhouse crops in the ground because quality is greatly improved. She gets larger flowers, taller stems and fewer insect problems with ground-grown tulips than with crate-grown ones. Her winter crops include typical cool-weather crops such as freesia, snapdragons and lupines, but she also grows sunflowers all winter long in 1801 flats. These produce nice “bouquet” sunflowers, Stamback said. Greenhouse production also enables her to grow species she couldn’t otherwise, such as trachelium and delphinium. These can’t be field grown at all due to high winds and short stems. One of Stamback’s favorite sayings is, “I just need two more greenhouses!”

Many growers agree with her, since greenhouses, hoophouses and high tunnels offer a way to compete with imported cuts. In her book “Flower Confidential,” Amy Stewart makes the strong point that most cut flowers bought in this country were not grown here. South American growers have started adding more specialty cuts to their mix and they can grow year round. But, as discussed here, U.S. cut flower growers are still in the game, with many choosing to extend their seasons into late fall, early spring or even year round.

About The Author

Lane Greer, Ph.D., is based in Portland, Ore., and is working on her first book. She can be reached at lanegreer@msn.com.

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