Once you’ve had a great year selling cut flowers, you may experience the temptation to extend your season by growing flowers in a heated greenhouse. For growers in most parts of the country, that’s the only way to get into the market in time for the big flower holidays of Easter and Mother’s Day, let alone the biggest flower day of all, Valentine’s Day.

But if your ambitions are pointing you in the direction of greenhouse growing, slow down and proceed with caution. Profits are not guaranteed, even if you succeed in producing beautiful flowers. Heating costs can quickly eat up any money to be made. Although fuel prices are currently lower than last year, they are not stable and a price hike in the middle of your production cycle can wreak havoc.
“You don’t want to sink a lot into it,” advises Vicki Stamback of Bear Creek Farm in Stillwater, Oklahoma, who has been researching winter production for five years. “Start small and see what works for you.”

In three recent studies, several species of greenhouse-grown cut flowers lost money because of heating costs. A few other species were profitable. It’s difficult to draw any hard-and-fast conclusions from these studies because there are so many variables that make each farm different. Weather, latitude and light intensity, greenhouse construction and scheduling will all have an effect on cost of production. The market price for flowers when the crop is ready will affect revenue.

Within all those variables is the potential for some growers, especially those in the South, to make money this winter. Here are summaries of the three research projects that point out the potential and pitfalls:

Dutch iris
Throughout much of the South, tobacco farmers have greenhouses that are used for a short period in spring to produce tobacco transplants, but sit empty the rest of the year. Researchers at Virginia State University in Petersburg were seeking a crop that could use those tobacco greenhouses in their down time to generate cash for the farmers. Carl Niedziela Jr., Extension horticulturist and research scientist, tried growing Dutch iris in a tobacco greenhouse.

Precooled bulbs of the varieties ‘White Wedgewood’ and ‘Ideal’ were planted October 19 and 20 in four different growing systems: in lay-flat bags; in bulb crates; in 32-cell Speedling float trays; and in 10-inch bulb pots. The plants were grown at 50-55°F and fertilized weekly with calcium nitrate at 400 ppm. There were some problems with plants coming out the wrong holes of the lay-flat bags and out the sides of the bulb crates, but in general, all systems worked well.

The iris bloomed from December 20 to January 31. Stem length was over 20 inches under all systems, with the tallest stems from the ‘Ideal’ iris grown in bulb crates. The lay-flat bags were quickest to harvest. And the plants grown near the edges of the greenhouse, where it was coolest, were the slowest to bloom. About 98% of the bulbs produced a marketable flower.

Heating fuel that year ranged from 87 cents to $1.77, with an average of $1.29 per gallon. Dividing the cost of heating the greenhouse by the number of stems it could produce (based on smaller samples), Dr. Niedziela figured that heat cost 18 cents a bulb. The bulbs themselves cost 13-14 cents each. Adding in all the other costs of production, including the cost of purchasing the pots, trays, etc., resulted in the following cost per stem for each type of growing system:

Lay-flat bags – 52 cents per stem
Bulb pots – 63 cents per stem
Bulb crates – 64 cents per stem
Speedling float tray – 65 cents per stem

Unfortunately, at that time the wholesaler was paying 25-50 cents per stem for Dutch iris. Retail florists were paying 40-80 cents per stem. Selling to a wholesaler at those costs and prices would cause a grower to lose money; even the highest prices from retail florists made the endeavor minimally profitable.

Dr. Niedziela cautioned that several factors might have inflated costs in this project above what other growers could experience. “This tobacco transplant greenhouse was double poly,” he said. “However, the side curtains were very leaky. So that cuts into the energy efficiency. The end wall in this house was single-layer polycarbonate. That is another negative. We could probably do some things to increase the efficiency such as inflatable side curtains, etc. “We also may have over-estimated our costs with respect to some of the reusable items such as containers.” Even with those caveats, this study is a red flag for anyone considering doing a relatively cheap cut flower such as Dutch iris in a heated greenhouse.

Snapdragons
In another project by Virginia Cooperative Extension, researchers found that low market prices and high heating costs made snapdragons extremely unprofitable. In 1996-97, the researchers grew 18,681 snapdragons in a 30×200 foot tobacco transplant greenhouse. With a 90% yield of saleable stems, they produced about 1,700 bunches of 10 stems. At $4 per bunch on the wholesale market, the crop was worth $7,200.

Production costs, however, were $9,417, not including labor. The biggest problem was the cost to heat the greenhouse. Researchers had estimated it would cost $800; in reality it cost $3,481.
Even if the price for snapdragons had been $5.50, the flowers would have produced a net return of less than $500. With labor estimated at 200 hours to plant, grow, harvest, sleeve and deliver the product, that comes to an hourly wage of $2.50 for the grower.

Some of the expenses in this study seemed inflated. An experienced grower would probably grow this crop for much less money; you can find a table of expense estimates to figure out if you could do better:http://www.ext.vt.edu/news/periodicals/fmu/1997-04/flowers.html.

Other flowers
Valuable cut flowers such as lupines, delphiniums and anemones can cost more to produce than they generate in sales. But some flowers can be profitable with no heat or minimal heat and a few are such great producers that it may pay to heat the greenhouse to 50°F.

That’s the mixed bag of results obtained by Dr. John Dole of North Carolina State University. He conducted the research when he was at Oklahoma State University, with the help of graduate student Todd Cavins and professional grower Vicki Stamback of Bear Creek Farm in Stillwater, Oklahoma. The results were published in HortTechnology in October-December 2000.

The research was done over two years, and involved eight types of flowers – anemone, snapdragon, larkspur, delphinium, sunflower, lupine, stock and pansy. In the first year, plants were grown in an unheated greenhouse and a 55°F greenhouse. They were planted mid-December and harvested beginning in late March.

In the unheated greenhouse, Lupine ‘Bright Gems’ and pansy ‘Oregon Giant’ were slightly profitable. Snapdragon ‘Animation’ was quite profitable. Anemone, Delphinium, Larkspur, and stock all lost money because production was low. One 22°F night inside the unheated house killed delphiniums and set back other plants, but in general the temperature inside the unheated house did not go below freezing.

In the 55°F greenhouse, only lupine ‘Bright Gems’ was profitable. Anemone, delphinium, larkspur, pansy, snapdragon and stock all lost money because of the cost of heating.

In the second year of the study, greenhouses were heated to a minimum night temperature of 36°F and 50°F. Anemone, larkspur, lupine, snapdragon, stock and sunflower ‘Sunrich Orange’ were grown in both houses. Plants were sown in mid-September this time, and harvested from 49 days to six months later.

In the minimally heated house at 36°F, larkspur and snapdragon were quite profitable. The others lost money.

In the 50° greenhouse, larkspur, lupine and snapdragon were profitable. Larkspur performed equally well in both houses, but was more profitable in the minimally heated house because of the lower heating costs. Snapdragon yielded better and had a shorter crop time and was consequently more profitable in the 50°F greenhouse. However, stems were about 5 inches shorter in the warmer greenhouse.

Although this project is tantalizing in showing crops that will perform well in unheated or minimally heated greenhouses, it’s important to note that Oklahoma’s weather is much milder than many places in the U.S. It’s in USDA Plant Hardiness Zone 7, with an average low temperature of 0 to 10 degrees. The winters when this research was conducted were typically mild, and therefore required less fuel than growers in other parts of the country would need to use to heat greenhouses to acceptable temperatures.

Better choices
Since that research was conducted, Vicki Stamback has gone on to build three greenhouses of her own where she grows flowers in winter. “From all that work, we found out that something in the middle is best; unheated wasn’t good and heating to 60° wasn’t good,” she said. “What I finally settled on was 45° at night. It’s warm enough that it doesn’t slow down the production schedule, but it’s not so warm that it eats up fuel.”

Vicki now focuses on five winter crops: ranunculus, sweet peas, snapdragons, freesia, and lupines. In a future issue of Growing for Market, we’ll tell you more about Vicki’s winter production.