GLASSHOUSE / GREENHOUSE HORTICULTURE
Below is an overview of what’s involved in glasshouse/greenhouse horticulture.
Other pages (to be developed) will show work done by Crophouse in various fields.
Protected cropping & controlled environment
Greenhouses & glasshouses provide shelter to crops from adverse weather conditions and they extend the growing season in cooler climates. Due to trapping solar energy, greenhouses generally have an above-ambient temperature. This is an advantage in cool weather, but a complication in hot weather.
Modern glasshouses are high-tech growing facilities that give very high yields of high-value crops, often out-of-season and outside the natural habitat of the plant species.
Modern greenhouse horticulture is intensive in terms of capital, technology, know-how, labour, energy and fertilisers. Unlike field crops, most greenhouse crops are grown nearly year-round. Some crops require work every day and many are picked several times a week.
Nearly all the conditions around the plants can be modified, both above-ground and in the root-zone. Many greenhouse crops, especially vegetable crops are grown ‘soil-less’, either in a growing medium or in a variation of water culture.
Vegetable and fruit crops. Most popular greenhouse-grown crops world-wide are tomatoes, sweet peppers (aka capsicums), cucumbers, eggplant and strawberries. Also very common are green-leaf vegetables such as lettuces, spinach, rocket and herbs such as sweet basil. Far less common are melons, grapes, raspberries and other berries, beans, sprouts, and tropical crops like bananas and ginger. In cooler climates, greenhouses are also used for production of cauliflower, broccoli, leek, radish and the like.
Ornamental crops. Also very important world-wide are ornamentals: cut flowers, potted flowering plants, potted green plants, garden plants, container shrubs and trees, even water plants for garden features.
Special crops include medicinal and pharmaceutical plants, young plants (e.g. tomatoes, capsicums etc.) sold to other greenhouse operators, seed potatoes grown in hydroponc greenhouse systems. Greenhouses are also used for overwintering of containerised trees including cherry trees, or housing algae reactors.
Intensive growing methods & very high yield
The yield (or rate of production) in a greenhouse can be ten times higher than in the field. E.g. top tomato yield achieved in a high-tech cooled glasshouse in Arizona was over 1000 ton/ha/year or over 100 kg/m2/year. In comparison, many field-grown crops or fruit trees produce up to 70-80 ton/ha/year (yield in greenhouses is often expressed per m2, and one hectare is 10,000 m2).
The very high yield is achieved by intensive cropping methods, optimal growing conditions and extended season. Yield must be high to recover the extra costs. Most greenhouse operators do not aim for maximum production but for optimum productIon: they improve the growing conditions not further than where the extra costs are earned back by extra production.
Consumers in most western markets expect greenhouse produce to be high quality. In some cases, improving produce quality is the reason for moving production from the field to the greenhouse. There are different quality parameters for different crops and for different markets. Quality parameters can include: flavour, aroma, size, colour, ripeness, firmness/softness, shelf-life, blemish-free, residue-free, free of signs of plant pests and diseases, with/without leaves, with/without calix, and much more. In western markets, there are more and more requirements for sustainable production methods, low footprint for carbon or water, regional or seasonal production, and more.