Energy-Efficient Annuals: Ageratum & Cosmos

Slideshow: Ageratum & Cosmos

Scheduling annual bedding plants in flower for specific market dates is of increasing importance to many greenhouse growers. During the past several years at Michigan State University (MSU), we have performed experiments with many seed propagated annuals to quantify how temperature and daily light integral (DLI) influence flowering time and plant quality. In the fifth article of this series, we present information on ageratum and cosmos and then use crop timing data to estimate greenhouse heating costs at different locations, growing temperatures and finish dates.

Materials and Methods

Seeds of ageratum (Ageratum houstonianum ‘High Tide Blue’) and cosmos (Cosmos sulphureus ‘Cosmic Orange’) were sown in 288-cell plug trays by C. Raker & Sons, and then grown in controlled environmental growth chambers at MSU at 68°F (20°C). Inside the chambers, the photoperiod was 16 hours and the DLI was 9 to 11 mol∙m¯²âˆ™d¯¹.

When plugs were ready for transplant (27 days after seed sow for ageratum and 16 days for cosmos), they were transplanted into 4-inch pots and grown in greenhouses with constant temperature set points of 57, 63, 68 and 73°F (14, 17, 20 and 23°C). At each temperature, plants were grown under a 16-hour photoperiod with two different DLIs provided by a combination of shade curtains and different light intensities from high-pressure sodium lamps.

Ageratum does not require long days for flowering, but plants flower faster if long days are provided. Cosmos ‘Cosmic Orange’ is a day-neutral plant and flowers in the same time if provided with short or long daylengths. However, some cosmos varieties flower faster when grown under short days.

The experiment was performed twice to obtain average DLIs that ranged from 3 to 19 mol∙m¯²âˆ™d¯¹. To give perspective, a DLI of 3 mol∙m¯²âˆ™d¯¹ is received in a northern greenhouse on a cloudy day in the winter. A DLI of 19 mol∙m¯²âˆ™d¯¹ is typical for a mid- to late spring day. The flowering date was recorded for each plant when ageratum had two open flowers and petals of cosmos were fully reflexed. When each plant flowered, plant height, number of leaves and branches and number of flowers and flower buds were recorded.

Crop timing data was used to develop mathematical models to predict flowering time and plant quality under different temperature and DLI conditions. The scheduling models were validated by growing ageratum and cosmos at three different constant temperatures to compare predicted flowering times with actual times. The Virtual Grower software (available free at www.virtualgrower.net) was used to estimate the cost to heat a 21,504 square foot greenhouse (about half an acre) to produce each crop for different finish dates and at different locations in the United States.

Results

In both ageratum and cosmos, time to flower decreased as average daily temperature increased and DLI increased. For example, time to flower in ageratum ‘High Tide Blue’ grown under a DLI of 10 mol∙m¯²âˆ™d¯¹ decreased from 61 days at 58°F to 27 days at 73°F (Figure 1). We were a bit surprised by the substantial flowering delay when ageratum was grown cool because many consider it a cool-growing (cold-tolerant) crop. Flowering time of cosmos ‘Cosmic Orange’ was similar: It decreased from 66 to 31 days as temperature increased from 58 to 73°F (Figure 2).

In both crops, higher light levels accelerated flowering more when plants were grown cool than at warmer temperatures. For example, as DLI increased from 3 to 8 mol∙m¯²âˆ™d¯¹, time to flower in ageratum grown at 58°F and 73°F decreased by 15 days and seven days, respectively. There was no acceleration in flowering when the DLI exceeded 10 mol∙m¯²âˆ™d¯¹ for ageratum and 7 mol∙m¯²âˆ™d¯¹ for cosmos.

Using this crop timing data, we identified dates that 288-cell plugs need to be transplanted for two different market dates when grown at different temperatures (Table 1).

Temperature and DLI had different effects on the number of flower buds at first flowering in cosmos and ageratum. In ageratum, flower bud number was primarily influenced by temperature, whereas in cosmos, flower bud number was primarily influenced by DLI. For example, ageratum had six more flower buds when grown at 58°F versus 73°F (Figure 1). In cosmos, plants grown at 63°F and under a DLI of 15 mol∙m¯²âˆ™d¯¹ had 15 more flower buds than plants grown at the same temperature, but under 5 mol∙m¯²âˆ™d¯¹.

In both crops, as the DLI increased from 3 to 19 mol∙m¯²âˆ™d¯¹, the number of lateral branches at flower increased by two to four. Therefore, although plants did not flower faster as DLI increased above 10 mol∙m¯²âˆ™d¯¹, plant quality improved because plants had more flowers. Plant height at flower increased as constant temperatures increased from 58 to 73°F. Under a DLI of 10 mol∙m¯²âˆ™d¯¹, ageratum and cosmos were 2.6 inches and 5 inches taller, respectively, at a constant temperature of 73°F versus 58°F.

Heating Costs

We can use this crop timing information with Virtual Grower to determine if it is more energy efficient to transplant a crop earlier and grow cool versus transplanting later and growing warm. For example, to produce an ageratum or cosmos crop for April 1 in Grand Rapids, Mich., New York, N.Y., or Cleveland, Ohio, heating costs per square foot would be 27 to 42 percent lower at 73°F versus 58°F (Table 2).

In contrast, to produce these crops for the same market date in Charlotte, N.C., and Fort Worth, Texas, a production temperature of 63 or 68°F would consume the least energy for heating. San Francisco was the only location tested that had lower predicted fuel consumption when crops were transplanted early and grown at 58°F for a market date of April 1.

At some locations, the production temperature that had the lowest heating costs per square foot per crop varied between market dates. For example, ageratum grown for April 1 in New York had the lowest predicted heating costs when grown at 73°F. In contrast, for a market date of May 15, estimated fuel costs were lowest if grown at 63, 68, or 73°F. In this example, because there is no difference in heating costs to produce ageratum for May 15 in New York at 63 to 73°F, other factors such as plant quality, availability of labor, overhead costs and opportunity costs could be considered when selecting a growing temperature.

Leave a Reply

More From Plant Culture...
More and more people are employing a landscape service, but that doesn’t mean they don’t still garden

September 2, 2015

Under Siege? Not Really, Just Go For A Walk

I have no trouble with people buying chocolates or wine instead of flowers to celebrate anniversaries, birthdays or peoples’ lives. We should all have choices. However, the other night I felt like I was entering the Republican caucus. I was minding my own business by the television set and became more than a little upset. A website called insteadofflowers.com came on the screen. It provided serene music and wholesome images of busy women doing busy things. It turns out that such busy women enjoy a small token of appreciation, but apparently their enjoyment, according to the voice-over, does not include flowers. This website delivers meals to the house, anything from beef brisket to beef bourguignon. It is a fine website with a good idea. But why pick on us? Why not use “insteadofbaloneysandwiches.com” or “insteadofgrilledcheeseandsoup.com,” “insteadofburgerdoodle.com,” or a dozen other things. When did flowers get to be the whipping boy? […]

Read More
Triathlon BA container shot

September 2, 2015

OHP Launches Triathlon BA, Offers Marengo SC In Smaller Size

Triathlon BA biofungicide/bactericide is now available to authorized OHP distributors for shipment to states where product registration has been approved. State registration information is available here. A next generation preventive biological fungicide, bactercide Triathlon BA is labeled for use in both organic and conventional production on a wide variety of fungal and bacterial diseases on ornamentals, fruits, vegetables and herbs and spices. With the active ingredient Bacillus amyloliquefaciens, Triathlon BA provides preventive control of many foliar and soil-borne diseases such as botrytis, powdery mildew, downy mildew, rusts, leaf spots, alternaria, pythium, phytophthora, rhizoctonia, fusarium and bacterial spot. Triathlon BA, an aqueous suspension formulation, prevents establishment of disease-causing fungi and bacteria on the plant tissues. Depending on the target disease, users can foliar-apply or soil drench Triathlon BA. Repeat applications may be made at three- to 28-day intervals. Under environmental conditions that are conducive to disease development, users may apply at three- to […]

Read More

September 2, 2015

Delegation Is Key To A Successful Greenhouse Operation

In a packed room at Cultivate’15, speaker Bernie Erven presented key steps growers need to take to improve their delegation skills, the benefits of delegating and the dangers of not learning how to delegate. This is a skill, he says, that everyone needs to learn. “For all of you who are part of a family business, you are choosing not to do things the easy way,” Erven laughed, as he presented a list of ways to know whether or not you’re an effective delegator. The owner of Erven HR Services, LLC, Erven has been working with and observing family businesses for many years. In his presentation, he said, he didn’t share anything that he hasn’t seen first-hand. You might not be a good delegator if you: Tend to be a perfectionist Work more hours than anyone else Lack time to explain clearly and concisely Are often interrupted Enjoy what you used to […]

Read More
Latest Stories

August 19, 2015

Greenhouse Growing Recommendations For Lobularia

Modern-day Lobularias are garden classics with good vigor and long bloom times. These growing recommendations will help keep your crop in prime condition.

Read More
Mike McGroarty, owner of Mike’s Backyard Nursery

July 29, 2015

Backyard Success: Mike McGroarty Educates Aspiring Grow…

Mike’s Backyard Nursery sits on a long, narrow, 5-acre property located in Perry, Ohio. There, customers can find a variety of flowering shrubs available, all in 2-quart pots, and all for sale for $5.97 each. Owner Mike McGroarty, a lifelong resident of Perry, says the town has a lot of plant nurseries, including 100 wholesale growers within a 10-mile radius of his house. That doesn’t discourage McGroarty, because he knows that while there are a lot of nurseries in his area, no one else is doing what he is doing. McGroarty has learned about plants — and marketing them to his audience — through decades of experience. He has never hesitated to pass along his knowledge to other growers looking to start their own backyard operations, and has created an entire program to educate aspiring growers. McGroarty Likes To Practice What He Preaches McGroarty’s operation serves as the laboratory for […]

Read More
cannabis, marijuana plant

June 27, 2015

Concern Grows Over Unregulated Pesticide Use On Cannabi…

As most growers know well, the federal government regulates all insecticides, fungicides, herbicides and other commercial chemicals used on agricultural crops. Therein lies the problem with use of chemicals on cannabis crops – so far, the feds want nothing to do with legalized marijuana. According to “Concern Grows Over Unregulated Pesticide Use On Cannabis,” a June 17 article on the National Public Radio (NPR) network by Agribusiness Reporter Luke Runyon, the lack of regulated chemicals for cannabis has left growers to experiment on their own. “In the absence of any direction the subject of pesticide use on the crop has just devolved to whatever people think is working or they think is appropriate,” said Colorado State University Entomologist Whitney Cranshaw in the NPR report. “Sometimes they’ve used some things that are appropriate, sometimes unsafe.” Denver officials held tens of thousands of marijuana plants earlier this year due to safety concerns, but […]

Read More
Great-spangledFritillary

June 16, 2015

The Butterfly Effect: Insect’s Wings Key To Azalea Poll…

A researcher from North Carolina State University (NC State) has found that in the case of the flame azalea (Rhododendron calendulaceum), all pollinators are not created equal. In fact, due to the flower’s unique reproductive structure, butterflies — and specifically, their wings — are the key to pollination. The flame azalea is commonly found in the Appalachian Mountains, ranging from as far north as New York to Georgia in the south. Like most azaleas, the flowers are large, and have an unusual structure: both the anther (male) and stigma (female) parts are very elongated and separated from one another. NC State biologist Mary Jane Epps was interested in how the azalea’s flower structure affected its pollination. “In order for a plant to reproduce, a pollinator — usually an insect — has to spread the pollen from the anther to the stigma,” Epps says. “In the case of the flame azalea, […]

Read More
Bee on a Sedum

March 17, 2015

4 Key Pollinator Research Projects To Be Funded By Hort…

The Horticultural Research Institute will grant $125,000 in financial support for four key projects as part of the Horticultural Industry Bee & Pollinator Stewardship Initiative. The Initiative has three primary goals. First, to convene a task force to develop a bee and pollinator stewardship program, including creation of best management practices for plant production. Second, to identify and fund research that will help answer key science questions and fill gaps needed to design and refine the stewardship program. Third, to seek to positively position the horticultural community and its customers by collaborating with other compatible groups interested in augmenting pollinator habitat and protection.

Read More

March 11, 2015

Pollinator Initiative Promotes Bee-Friendly Talking Poi…

AmericanHort and the Society of American Florists are working tirelessly with the ornamental industry's Pollinator Stewardship Initiative on a number of new projects.

Read More

February 11, 2015

Infusion Technology Boosts Seed Performance, Study Sugg…

Seven-year-old wheat seed germination can increase by as much as 83 percent, according to a Vital Force Technology Study that looks at the effects of energy infusion technology on plant vitality.

Read More

February 3, 2015

American Floral Endowment Accepting Research Pre-Propos…

If you are pursuing a floriculture research project, now is the time to apply for funding through the American Floral Endowment. Research pre-proposal applications for 2015-2016 funding are due to AFE by June 1, 2015.

Read More

January 27, 2015

Marijuana’s Trajectory And Ascent To Horticultural Cr…

Marijuana growing is poised for change as growers and researchers focus on improving production practices.

Read More

December 9, 2014

Greenhouse Production: Two Years Of Basics & Beyond…

Greenhouse Grower's Basics & Beyond articles cover some of the latest news and research going on in greenhouse production. Here are article links for the last two years.

Read More
GrowIt! App Wins Gold At Design100 2014 US Mobile & App Design Awards

November 24, 2014

GrowIt! App Wins Gold At Design100 2014 US Mobile &…

The social garden app GrowIt! takes the Gold Winner award at the design100 2014 Mobile & App Design Awards.

Read More

November 10, 2014

The Perennial Farm Joins HGTV HOME Plant Collection

The Perennial Farm joins the HGTV HOME Plant Collection growers' network for 2015.

Read More
AmericanHort

November 4, 2014

AmericanHort Publishes Revised American Standard For Nu…

AmericanHort announces the revised American Standard for Nursery Stock (ANSI Z60.1) is now available for industry use. The Standard reflects the consensus of the industry regarding how nursery stock — living plants other than annuals — should be specified and sold within the trade.

Read More

September 26, 2014

Master The Art Of Watering

Watering is elemental to healthy plants, but one of the hardest concepts for new employees to master in the greenhouse. Recommend these tips to start them off right.

Read More

September 16, 2014

Ball FloraPlant’s Las Limas Facility Provides Gro…

Ball FloraPlant’s Las Limas farm in Esteli, Nicaragua, is one year away from full production, but sales and quality from the two-year-old facility are right on track.

Read More
Erysimum 'Cheers' from Darwin Perennials

September 15, 2014

Darwin Perennials Takes Production Offshore In Bogota, …

With its recent purchase of a farm in Colombia, Darwin Perennials is ready to amp up supply of its perennial genetics, to provide growers with tried-and-true varieties and comprehensive production specifications.

Read More

July 23, 2014

Plan Now To Prevent Bract Edge Burn On Poinsettias

Reduce fertilizer and water, and allow your poinsettias to develop slowly during the final four weeks of production to avoid bract edge burn.

Read More

July 11, 2014

Growing Your Crops Above Their Base Temperature

Lowering temperature set points in the greenhouse may help you combat rising heating costs.

Read More