The new ‘smart’ greenhouses The first crops of tomatoes and cucumbers grown inside electricity-generating solar greenhouses were as healthy as those raised in conventional greenhouses, signalling that “smart” greenhouses hold great promise for dual-use farming and renewable electricity production. “We have demonstrated that ‘smart greenhouses’ can capture solar energy for electricity without reducing plant growth, which is pretty exciting,” said Michael Loik, professor of environmental studies at the University of California, Santa Cruz, and lead author on a paper that appears in the current issue of the American Geophysical Union’s journal Earth’s Future. Electricity-generating solar greenhouses utilize Wavelength-Selective Photovoltaic Systems (WSPVs), a novel technology that generates electricity more efficiently and at less cost than traditional photovoltaic systems. These greenhouses are outfitted with transparent roof panels embedded with a bright magenta luminescent dye that absorbs light and transfers energy to narrow photovoltaic strips, where electricity is produced. WSPVs absorb some of the blue and green wavelengths of light but let the rest through, allowing the plants to grow. WSPV technology was developed by coauthors Sue Carter and Glenn Alers, both professors of physics at UC Santa Cruz, who founded Soliculture in 2012 to bring the technology to market. Loik’s team monitored photosynthesis and fruit production across 20 varieties of tomatoes, cucumbers, lemons, limes, peppers, strawberries and basil grown in magenta glasshouses at two locations on campus and one in Watsonville, California. “Eighty per cent of the plants weren’t affected, while 20 per cent actually grew better under the magenta windows,” said Loik. Tomatoes and cucumbers are among the top greenhouse-produced crops worldwide, he added. In additional experiments, small water savings were associated with tomato photosynthesis inside the magenta glasshouses. “Plants required five per cent less water to grow the same amount as in more conventional glasshouses,” he said. “I thought the plants would grow more slowly,because it’s darker under these pink panels. The colour of the light makes it like being on the Red Planet,” said Loik. “Plants are sensitive not just to the intensity of light but also to colour. But it turns out the plants grow just as well.” Reducing the energy consumed by greenhouses has become a priority as the global use of greenhouses for food production has increased six-fold over the past 20 years to more than nine million acres today – roughly twice the size of New Jersey, according to Loik. “It’s big and getting bigger,” he said. “Canada relies heavily on greenhouses for vegetable production, and their use is growing in China, too.” Plastic greenhouses are becoming popular for small-scale commercial farming, as well as for household food production, he added. Greenhouses use electricity to control temperature and power fans, lights, and other monitoring systems. “This technology has the potential to take greenhouses offline,” said Loik, who specializes in climate change, plant physiology, water resources and sustainable technologies. Cost per panel of WSPV technology is 65 cents per watt – about 40 per cent less than the per-watt cost of traditional silicon-based photovoltaic cells. “If greenhouses generate electricity on site, that reduces the need for an outside source, which helps lower greenhouse gas emissions even more,” said Loik. “We’re moving toward self-sustaining greenhouses.” Additional coauthors include Catherine Wade, who participated as a graduate student, Carley Corrado, who participated as a postdoctoral researcher, and undergraduates David Shugar and Devin Jokerst, all of UC Santa Cruz; and Carol Kitayama, senior grower at Kitayama Brothers Growers. Jennifer McNulty is the strategic communications director/social sciences writer at the University of California, Santa Cruz. FOR MORE FEATURES ON ‘ENERGY MANAGEMENT,’ VISIT GREENHOUSECANADA.COM. Coreopsis Li’l Bang Daybreak is a long blooming perennial for sunny areas. Perennials are a modern gardener’s dream – that’s what more and more garden centre customers are realizing. “You only have to plant them once of course, and they are low maintenance,” says Dena Gavin, a professor in the school of Environment and Horticulture at Niagara College in Ontario. “You usually only have to touch them once or twice a year. They are economical and attractive, with lots of colour and texture now available. A properly planned perennial bed will bloom all year.” At outlets of Sheridan Nurseries across southern Ontario, sales of perennials continue to grow, notes president and CEO Karl Stensson. “They are being planted where once shrubs and evergreens were planted en masse,” he explains. “Grasses especially, as well as long-blooming lilies such as Stella D’oro, are planted everywhere in the landscape here in Toronto.” The places perennials can be planted are also expanding, notes Stensson. “In our market, backyards are becoming smaller,” he says, “and more people are incorporating many shapes and sizes of containers into their landscape.” The demand, therefore, for smaller, more compact perennials continues to be strong, but Sheridan Nurseries is also selling perennials in much larger sizes than in the past,accommodating gardeners with more space who don’t want to wait a year or two for their plants to fill out. “Nowadays we hardly sell any fourinch potted perennials,” Stennson says. “The norm is one gallon but it’s not uncommon to see two and five-gallon perennials.” Brighter colours in foliage or flower is also a current trend, along with longer bloom times, notes Mark Cullen, who heads the gardening division at national retail chain Home Hardware. The explosion in popularity of hydrangeas, he says, well illustrates how much consumers like low maintenance and long-lasting colour, as does the growing demand for different coloured varieties of Black-Eyed Susan (rudbeckia), echinacea, Russian Sage and other plants. Brian Minter, the co-owner of Minter Gardens in Chilliwack, B.C., agrees that colour vibrancy across the spectrum is what today’s garden centre customers want to buy and bring home. “They want contrasts in colour and texture in their gardens and especially in containers, so that every plant adds value to the other plants in the grouping,” he notes. “Carex grasses are becoming more popular – Everillo especially with its nice gold colour. And people want perennials that are going to look good longer (over the season), with repeat flowering, earlier flowering,versatility in terms of where you can plant them (sun/shade).” This year, Minter Gardens sold an increasing number of giant hibiscus (suitable to zone 4), a large plant that offers ongoing flowering of huge blossoms. While they get going relatively late in the season, Minter says these perennials provide a fresh new “wow.” NEW WAYS OF MARKETING In terms of perennial marketing trends, Cullen notes that signage, direct sales help and good merchandising are all very powerful in steering customers towards great performing plants such as rudbeckia ‘Goldstrum’ or shasta daisy ‘Becky.’ Displays that highlight the best attributes of new perennials are also important. “People buy colour,” Cullen explains. “Larger format plants (very few four-inch plants) such as lots of gallon and two-gallon stock equal better displays, more colour, greater impact.” Cullen adds that tags on perennials need to follow suit – needing to be larger and more colourful. They should also provide detailed information, such as “when the plant is out of bloom,” he says, because “customers often base their buying decision on the tag.” Stensson adds that at Sheridan, they have chosen to display perennials by their common name, making it easier for customers to be sure of what they’re buying. Minter, however, asks “how inspiring is a small green plant with a tag showing it in bloom?” He would like to see Canadian greenhouse operators enable garden centres to radically change perennial marketing following the Denmark model, where perennials arrive having been forced into bloom so that people can see them at their fullest beauty and therefore be more inclined to buy them. Minter asserts that “perennials should all be in bloom in the spring and they should be larger and ready to make an immediate difference in customers’ gardens. Our thinking is still too traditional in that we are pre-judging what people want. Price is secondary to people these days, and it is how perennials are presented that really matters.” For his part, Stensson believes that retailers who want to successfully market perennials need to shift their perception of them from being only garden/landscape plants to being “impulse buys” like annuals are. He says when in bloom, plants such as campanulas, echinaceas, rudbeckias, leucanthemums, phlox and veronica can be just as enticing as potted geraniums or begonias. Lastly, Stensson believes marketing through “collection” branding is here to stay. “From Big Bang Coreopsis and Dolce Heucheras to Sunsparkler Sedums, collections are becoming the norm, and they are competing for bench space,” he explains. “They provide retailers with a good story to tell their customers, but the challenge is deciding which one to embrace and which ones to leave behind.” Our thinking is still too traditional in that we are pre-judging what people want. NATIVE PERENNIALS Breeding native perennials to be prettier is also a strong current trend in Gavin’s view. Consumers have been exposed to a great deal of media coverage about reduced bee and monarch butterfly populations, she notes, and they want to do something about it. There are so many types of echinacea, lobelia and rudbeckias now, she says, adding that “I attended the annual symposium of the International Perennial Plant Association this summer and butterflyweed was chosen as plant of the year.” Minter, Cullen and Stensson all agree that concerns over pollinator populations has resulted in a surge of consumer interest in native species. “Plants such as asclepias, lavandula, monarda and nepeta are increasing in their popularity because of their appeal to these beneficial insects,” Stensson notes. “We have created our own Sheridan Garden Classic groupings of popular perennials such as Low Maintenance, Drought Tolerant, Bird and Butterfly, and new this year is our Bee-nificial collection.” He adds that sedums, echevera and sempervivens along with other drought-tolerant plants are becoming more popular as consumers look to reduce their environmental footprint. In addition, Minter adds that ferns of various textures and colours are a growing sales category, especially for containers, with their soft greens that have a calming, “feel-good” effect on people. A PERENNIALLY BRIGHT FUTURE Everyone believes that perennials will stay in strong demand for some time to come, especially plants that are garden-ready, colourful, well-labelled and well-maintained at the retailer. “The growers who are ready with number one stock when the season opens and the retailers who know how to merchandise and maintain their stock will be the winners,” Cullen says. “Bring on the new varieties, those that bloom longer, are more winter hardy, attract pollinators, and are fragrant. In that order.” However, while Stensson predicts further expansion of perennials into the different areas of the home landscape, he also warns against providing customers with too much choice. Simply put, too many varieties can overwhelm and intimidate, which can cause some customers to shop elsewhere. “While purists want to see hundreds of varieties of hostas, you can have 25 varieties and cover the gamut,” he explains. “Even then, the challenge is not to scare the consumer away with 25 choices of one plant.” He concludes that “we as independent garden centres have made gardening complicated and we need to uncomplicate it.” Treena Hein is a freelance writer in Ontario and a frequent contributor to Greenhouse Canada. FOR MORE NEW VARIETIES,VISIT THE ‘MARKETPLACE’ AT GREENHOUSECANADA.COM. Concerns over pollinator populations has resulted in a surge of interest in native species. Five Advantages of Energy Curtains Not to Miss Energy prices won’t likely go down, so savings are bound to go up. LEIGH COULTER When it comes to adding energy curtains (sometimes referred to as thermal blankets) to a greenhouse everyone focuses on energy savings. And certainly energy savings should be a major factor in any greenhouse grower’s decision to purchase energy curtains. In northern climates, winter growing adds expensive heating costs to the most diligent greenhouse operation. A well designed and properly installed energy curtain can reduce winter heating bills by up to 50 per cent and in some cases more. In turn, energy curtains when used properly in hot summer weather can cut back on electricity needs from fan venting, and help maintain higher nighttime temperatures when the sun goes down. But there are five other considerations worth adding to your analysis when considering the value of an energy curtain in your greenhouse. 1.Greenhouse energy curtains help control humidity: When used properly in conjunction with roof vents, an energy curtain can help balance humidity in the greenhouse by allowing fresh cool air in, while still providing a physical barrier to prevent the cold air from dropping to the crop. Learning how to control the curtains as part of your total environmental control is essential. If the curtain needs to be closed and humidity levels are too high, then opening the curtains a crack and opening your windows will help lower humidity. 2.Energy curtains can be used for summer shading: The flexibility with energy curtains allows growers to shade when the plants need it. By using your greenhouse curtain system to adjust light levels as well as temperature you have one more tool for providing the ideal growing environment for your specific crop. When working with your greenhouse design team to layout the greenhouse curtain system make sure you don’t miss this aspect of environment control, and set your zones according to the differences your crops may need. 3.Energy curtains produce healthier plants by reducing daytime temperature fluctuations: Getting rid of the peaks and valleys in a winter day’s temperature range will most certainly improve the bottom line as far as reducing heating costs. And that is only the beginning. Daytime temperature fluctuations may be causing your boilers to perform lower than expected, which reduces boiler efficiency and affects maintenance costs and lifetime use of a boiler. These rapid temperature changes also add stress to your plants. So by properly timing the opening and closing of an energy curtain with environmental controls that measure outside and indoor temperatures against desired growing temperatures, you can even out the peaks and valleys and provide a smoother temperature transition for healthy plants. 4.Energy curtains may qualify for a government rebate: In many parts of the United States, Canada and Europe, energy savings is high on government agendas. Get involved with your local chamber of commerce, and your regional, state and provincial government, and learn what rebates and tax saving incentives are available for energy efficient upgrades. If there is money available to help improve your business, then knowing what your options are will help you make smart decisions. 5.Energy prices won’t likely go down, so energy savings are bound to go up: When considering the ROI for an energy curtain or any other capital investment, including an assessment of the future makes good sense. Take a look at your energy bills for the last five years and consider trends. How has your price changed? What has your average usage been? If you had a mild winter and dramatically reduced your heating expenses, also consider the harsher winters because the future will have both. Thermal energy curtains are only one consideration that modern commercial growers have available to assist in providing the ideal growing environment for the crop. Additional curtain considerations like shade, or blackout (light deprivation), or double and triple hung curtain options, and truss-to-truss versus gutter-to-gutter operations can also be discussed with a GGS greenhouse specialist. If you have any remaining questions about greenhouse curtains contact us now for a free individual consultation – ggsstructures. com/mj. Leigh Coulter is the president of GGS Structures Inc. and Niagrow Systems Ltd. GGS has been building greenhouses for growers around the world since 1979. Energy curtains produce healthier plants by reducing daytime temperature fluctuations.
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