Exploring Alternative Growing Structures for Extending the Season and Improving the Quality of Organically Grown Cut Flowers

Exploring Alternative Growing Structures for Extending the Season and Improving the Quality of Organically Grown Cut Flowers

Summary

1. Project name and contact information
Evaluating various tunnel structures and covers for use in extending
the cut flower season
Janice Blomgren, Windflower Farm
585 Meeting House Road, Valley Falls, NY, 12185
518-692-3188, windflowerfarm@earthlink.net

2. Goals
Our goal in this project was to evaluate the performance of ten cut flower varieties in five kinds of tunnels at two to three planting dates.

3. Farm profile
Windflower Farm, owned and run by Jan and Ted Blomgren, is situated on 38 rolling acres in the Taconic Hills of southern Washington County, New York. We grow 10 to 15 acres of organic vegetables and cut flowers for sale to about 350 CSA shareholders in New York City and to shoppers at the Saratoga Springs Farmers’ Market. We also grow strawberries and raise a small laying flock.

4. Participants
Jan and Sue Kilpatrick, an employee of Windflower Farm during the 2004 growing season, were the primary researchers in charge of this project. They did all the plot work, including planning, planting, data collection and photography. Laura McDermott, a horticulture agent with Cornell Cooperative Extension (CCE) in Washington County, was a consultant on the project.

5. Project activities
Much of the trial, as described in the original proposal, was planted in the spring of 2004. A significant hailstorm and heavy rains in late May, and an unusually wet and cool 2004 growing season, hampered our progress with the project. Ruined plantings and flooding inside structures eliminated some of the plots from analysis, and wet field conditions prevented us from erecting the multi-bay tunnel. Nevertheless, much of the trial was out of harm’s way, and a fair amount of data was collected. In summary, the data we gathered reflected the performance of five to ten cut flower varieties, on two to three different planting dates, and in three to four different tunnel structures, depending on the variety.

We gathered temperature and relative humidity data from four different tunnel structures and the out-of-doors. We did not collect rainfall data, but note that outside crops were never wanting for moisture during the wet 2004 season, and crops under plastic were irrigated once or twice each week, as needed. Rainfall and other weather data (possibly including light levels) will be collected in 2005. We gathered quantitative floral quality data (e.g., stem and inflorescence length, stem number per plant, and stem girth) on five cut flower varieties (including stock, godetia, larkspur, snapdragon, and bells of Ireland), out of a total of ten that were planted, in three to four different kinds of tunnels. Of the remaining five flowers in the trial (including China aster, Asiatic lily, delphinium, sunflower and lisianthus), we made observations regarding their performance in the tunnels, but collected little quantitative information.

We’d like to repeat specific portions of the trial during the 2005 season. Specifically, we’d like to clarify the list of crops suitable for the Typar-covered tunnel by growing them again under Typar and under plastic. Among the list of flowers we’d like to include are early spring-planted larkspur, stock, snapdragon, and godetia, and late spring-planted lisianthus, bells of Ireland, China aster, and celosia. For the early spring plantings, we’ll use low tunnels inside the field tunnels for added protection during the first four weeks of growth, and we’ll replicate this planting in the high tunnel for an additional comparison. For the late spring plantings, we’ll include Covertan-covered low tunnels and field production in the analysis.

6. Results
A. Tunnel Environment
1. Temperature. In May, the highest temperatures recorded were inside the un-vented Typar-covered structure. The plastic-covered structures were ventilated, and remained cooler. The walk-in tunnel warmed more quickly in the morning than the high tunnel, although both were covered in plastic, because of the walk-in’s smaller size. Nighttime lows were similar in all tunnel/cover combinations, and these were only about one degree F warmer than the outside. The Typar-covered tunnel was opened along its east side during late May (the west side remained down the entire season), but still remained several degrees warmer than the high tunnel during most June days, and was the quickest to become warm in the morning. Among the plastic-covered units, highs were higher and lows lower in the walk-in tunnel compared with the high tunnel, again, probably because of the size (air volume) difference. In June, nighttime lows were lowest under Typar, which were similar to outside temperatures. The sides of the Typar tunnel were opened very high at the end of June, which improved air flow and lowered daytime temperature highs. The plastic-covered walk-in tunnel was generally the hottest during July, although it remained about one degree F cooler than the high tunnel during the night. The temperature patterns established in July also prevailed during August, with the exception that daytime highs were often lower inside the tunnels than they were outside. Shading, in the case of Typar, and condensation build-up on the plastic-covered units probably explain this.

2. Relative Humidity. In May, relative humidity was highest inside the plastic-covered units, intermediate in the out-of-doors, and lowest under Typar. In June, relative humidity was always highest in the high tunnel, and generally lowest under Typar (even when compared to outside RH). In July, the increased ventilation in the Typar unit increased the relative humidity under that cover. Relative humidity was lowest under the plastic-covered walk-in during July and August, which was similar to the outside.

B. Flower Performance
1. Stock stem length was greatest in the high tunnel (34 to 35”), lowest in the low tunnel (12“), and intermediate in the other structures (17 to 21”). Stock inflorescence length was generally shorter in earlier plantings compared to later plantings in the same tunnels. Inflorescence length was consistently greatest in the high tunnel. The Covertan- and Typar-covered tunnels produced intermediate results with respect to inflorescence length, and the plastic-covered field tunnel produced variable results.

(Tables with data are available from the SARE office in Burlington. They could not be posted with this report)

2. Larkspur stem length was similar across all the tunnels (42 to 48”). Inflorescence length was greater in the high tunnel (12”) than in the other structures (7”). The number of stems per plant (4) was similar across tunnels.

3. Snapdragon stem length was greatest in the earliest plantings, and longest in tunnels covered with plastic (32 to 39”). Covertan- and Typar-covered structures produced slightly shorter stems (27 to 28”). Snapdragon inflorescence length was shortest in the high tunnel (7”), and ranged from 9 to 12” in the other structures. The number of stems per plant ranged from two (in Covertan-covered low tunnels) to five (in Typar-covered field tunnels), with the high tunnel producing three stems per plant.

4. Godetia stem length was greater when grown in the high tunnel (36”) than in either field tunnel, regardless of the cover (plastic, 26 to 27” and Typar, 24”), but the long stems produced in the high tunnel were not as sturdy as those produced elsewhere. Plants grown in low tunnels under Covertan produced very short stems probably because of the wind and relative cold. The planting dates we used did not influence stem length.

5. Stem length in Bells of Ireland was greater in the high tunnel (45”) than in either field tunnel (Typar, 34” and plastic, 32”). The number of stems per plant was greatest in the field tunnel covered with plastic (6), and lowest in the Typar-covered field tunnel (3). Inflorescence length and stem diameter were similar across the tunnels. (Statice and Bupleurnum were substituted for Bells of Ireland later in the trial.) Statice performed very well in both the Typar- and Covertan-covered tunnels, which outperformed the field-grown crop. Bupleurnum performed very well in the plastic-covered tunnel (30”), and moderately well in the Covertan- and Typar-covered tunnels (18”). These flowers were not grown in the high tunnel.)

6. Lisianthus performed best in the high tunnel (good stem length, a high proportion of marketable flowers, and an excellent second harvest), fairly well in the plastic-covered field tunnel, reasonably well in the Typar tunnel (but losses to Fusarium, a soil-borne fungus, were highest in this structure), and poorly in the low tunnel because of shorter stems and ruined blooms from rainy weather. The number of stems per plant was similar in all structures.

7. China aster performed well in the high tunnel (>36” stems) and in the plastic-covered tunnel (>36”), fairly well in the Typar-covered field tunnel (>24”), although they suffered from aster yellows in this structure, and reasonably well in the low tunnel (about 24”), but they performed poorly (about 18”) when left uncovered in the field. Stem and blossom number per plant was similar across treatments.

8. Sunflowers grew too tall in most tunnel structures, regardless of the cover, and produced over-sized stems and undesirable flowers. Sunflowers grown in the low tunnel performed well, although stem size was still a bit large. The cover was removed when the plant reached the top of the hoop, and the plant went on to produce good blossoms. Sunflower quality was best when the plant was grown in an uncovered, unmulched environment. In the past, we have successfully grown sunflowers in plastic-covered field tunnels, and attribute our problems here to excessive compost rates.

9. Asiatic lilies performed well in the high tunnel and in the field tunnels, regardless of the cover, with stem length in the 30” range. Stems were 6 to 12” shorter in the low tunnels and in the field.

10. Delphinium performed fairly well across all tunnels, ranging in height from 24 to 30.”

7. Conditions
As noted above, a significant hailstorm in late May, accompanied by heavy rains, and an unusually wet and cool 2004 growing season, greatly influenced our ability to carry out the project as planned. Ruined plantings, flooding inside structures, and wet field conditions eliminated some of the plots and one type of structure from analysis, but much of the trial was successful. Good information was gathered on several of the flowers we were interested in, grown in a variety of structures. As we noted under section 5, we intend to repeat portions of the study during the 2005 season, and these results will be incorporated into our final report. The information we gathered in 2004 was impacted by growing conditions, but probably no more than is usually the case with field trials. A more “normal” season would have favored the Typar- and Covertan-covered structures, but this experience pointed out that the plastic-covered units do a better job of reducing weather-related risk.

8. Economics
We have identified several cut flower species that lend themselves to season extension using tunnels, and we’ve identified an economical field tunnel that produces high-quality cut flowers when covered with plastic. The economic ramifications of these findings are hard to state, but we’ll do our best for the final report. We’ll also provide a comparison of the costs of these structures and various covers.

9. Assessment
On a general level, we are seeking information that will help us match tunnel structures, covers and crops. Basically, we are looking for the least expensive combination of structure and cover that will give us the desired result (long and numerous stems and earliness) with our cut flower crop. We are beginning to gather the kind of information needed to make informed decisions of this kind. Numerous trials of this sort will be needed before a useful database can be developed. Nevertheless, this project has helped us to arrive at the following conclusions:

Covers. Plastic-covered tunnels have generally been superior to Typar- and Covertan-covered tunnels, regardless of the structure, and Typar and Covertan, in turn, have been superior to growing in the out-of-doors. These covers provide protection by degrees, with Covertan providing less day time warming, cooler night temperatures, and less wind protection, than Typar or plastic. Typar-covered tunnels have been little-researched, and not all cut flowers are suited to the unique environment inside a Typar tunnel. The cut flowers we’ve found most suitable to Typar tunnels so far are China aster, lisianthus, and bells of Ireland (if trellised) – all of which do well in a warm environment. Cool-loving crops such as stock, larkspur, and snapdragon have performed poorly in Typar tunnels unless the sides have been open for added ventilation or planting is done very early in the spring.

Structures. Low tunnels easily become too hot when covered with plastic, and probably require too much labor to ventilate economically. Even the walk-in tunnels covered with plastic can easily become overheated. The low tunnels covered with Covertan were probably too cold and windy in the spring to give good results. High tunnels have provided the best horticultural results. This may have had most to do with the material used to cover them, but the slightly superior results of these units compared to plastic-covered walk-ins shows that the size of the structure is important. The field tunnels have been nearly as good as the high tunnels when covered with plastic, and similar to the low tunnels when covered with Typar. One of the key advantages of high tunnels over plastic-covered field tunnels is the capacity of the high tunnel to withstand significant snow loads.

In the future, we will focus on plastic-covered field tunnels. In particular, we will be looking into various walk-in and drive-in (or tractor-accessible) single- and multi-bay structures to identify units that are cost-effective and relatively easy to manage. We will also look into clarifying the list of flower varieties and planting windows that are most suitable for Typar-covered structures.

10. Outreach
We have undertaken the first steps in our outreach plan. We have created a PowerPoint presentation that provides an overview of season extension for cut flowers using tunnels and a summary of our research findings. A presentation of some of these results is scheduled for the NOFA conference in 2005. More of these results will probably be presented at the New England Vegetable & Berry Conference in December of 2005. A newsletter article summarizing our findings will be written for CCE newsletters. And, in June of 2005, growers will be invited to an open house at our farm where they can see the tunnels themselves.

Submitted by Jan Blomgren, Windflower Farm, March 2005

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