The cultivation of greenhouse crops is the most intensive form of vegetal production. For instance, the production per cultivated unit area of a greenhouse tomato crop (>50 kg/ m2) is 10 times superior to that of a field crop. On the other hand, investment, labour and energy costs (about 40 PJ of fossil energy in Canada, which represents 12% of the total energy used in agriculture) are greater in this sector than in any other. However, the yield, quality and value of crops are correspondingly high. The greenhouse essentially provides a controlled climate that, in adverse conditions, may be adapted to the needs of particular crops. For example, in northern countries such as Canada, where outdoor cultivation is possible for only about 5 months of the year, greenhouses provide a temperature-controlled environment that shelters plants from low or high temperatures, heavy rain, strong winds, INSECTS and other pests.
Today's greenhouse industry uses the most modern technologies, which allow it to reduce their negative effects on the environment, to considerably improve the energetic efficiency of crops (used energy by unit production) and thus to remain competitive in national and international markets. New greenhouse technologies contribute constantly to increasing the production per cultivated unit area. These include (1) the optimization of greenhouse structures and coverings for better light transmissivity; (2) hydroponic cropping with recycling of greenhouse effluents for optimal growth; (3) the use of high-performance culture media that fulfill the root needs of the plant; (4) the enrichment of greenhouses with carbon dioxide to increase yields; (5) the use of photosynthetic lighting in winter to secure year-round production; (6) the computational management of climate (temperature, light, moisture, Co2), and of irrigation and fertilization control; (7) the use of rootstocks resistant to pathogens and more efficient in using water; (8) the biological control of insect pests and diseases; (9) genetic improvement and genetic engineering for the development of new varieties; (10) the mechanisation of operations to optimize labour; and (11) the conservation of energy and the use of renewable energy. For instance, greenhouse tomato yields increased from 120% to 150% in the last 8 to 10 years and cucumber yields increased from 80 to 100%, while energy use and labour requirements were reduced. Product quality (visual, nutritive, organoleptical and nutraceutical) and safety (eg, PESTICIDE-free crops) are now key elements of the greenhouse ORNAMENTAL and VEGETABLE market.
The greenhouse industry is an important and growing segment of the Canadian agrifood industry, with farm values around $2.5 billion (vegetable crops $1.2 billion) and a total surface of more than 2 000 ha. The major producing provinces by hectare are Ontario (1 044 ha, Leamington and Niagara areas), British Columbia (493 ha, Fraser River Valley), Québec (235 ha) and Alberta (116 ha). The greenhouse industry of the West differs from that of the East in many ways. First, the climate in BC growing areas is quite moderate (coastal climate), whereas the climate in the Eastern provinces is continental, with cold winters, hot and humid summers, and fluctuating light, temperature and humidity. Moreover, the length of day in BC, Ontario and Québec is not the same, and this has an affect on plant growth rates. Finally, the BC industry uses a Dutch model of technology (glass-covered greenhouses), whereas the industry in the Eastern provinces is modelled on a blend of European and North American technologies (glass and double-polyethylene-covered greenhouses).
The main greenhouse vegetable crops grown annually in Canada are TOMATOES (431 ha, 210 million kg), CUCUMBERS (224 ha, 23.2 million dozen), PEPPERS (215 ha, 51.4 million kg) and LETTUCE (9.3 ha, 23.5 million heads). The major species of greenhouse-grown cut FLOWERS are tulips (43 million stems), ROSES (34 million), gerberas (29 million), chrysanthemums (28 million), alstroemerias (18 million), lilies (18 million), snapdragons (17 million), irises (7.7 million), freesias (6.5 million), daffodils (3.5 million) and lisianthus (1.1 million). The industry also produces potted plants: 25 million GERANIUMS, 19 million tropical, foliage and green plants, 16 million chrysanthemums, 12 million African violets, 12 million hanging pots, 11 million miniature roses, 9 million poinsettias, 5.6 million impatiens, 5.2 million lilies, 5.1 million begonias, 4.4 million petunias, 4.1 million gerberas, 1.7 million azaleas, in addition to forest cuttings and transplants (806 million), bedding plants (570 million) and vegetable transplants (465 million).
In partnership with universities and private and public research centres such as Agriculture and Agrifood Canada, the industry is constantly searching for new varieties and sustainable, high-performing and affordable production methods to create higher yields and higher-quality plants, and to reduce the industry's impact on the ENVIRONMENT.
As a result of advertising, research, public education about healthy products and changes in consumer habits about fresh, tasty, biological foods that bring health benefits (antioxidants, carotenoids, lycopene, fibre, minerals, etc.), there is an increased demand for greenhouse products. The demand for products of proximity (food miles) and consumer concerns about the safety and traceability of imported foods also create an important economic advantage for Canadian greenhouses. Furthermore, a growing number of North Americans are spending more money on horticultural plants for gardening. Given the market potential, continuous research and efforts in the application of new technologies, production efficiency and marketability of Canadian products continuously increase. A great deal of marketing, engineering and horticultural crop management is devoted to ensuring the prosperity of one of the most important sectors of Canada's horticulture industry.