Greenhouse Vegetables

WHAT ARE GREENHOUSE VEGETABLES?

The main greenhouse vegetable crops in BC are tomatoes, sweet bell peppers, long English cucumbers and butterhead lettuce. Crops grown in a greenhouse can yield up to ten times as much as crops grown in the field. All of these crops are actually fruit. A fruit is the part of the plant that contains the seeds.

WHERE ARE GREENHOUSE VEGETABLES PRODUCED IN BC?

90% of the greenhouses are located in the Lower Fraser Valley.

HOW MANY GREENHOUSE VEGETABLES DO WE PRODUCE?

Annually, BC produces about 9000 tonnes of tomatoes, 6000 tonnes of cucumbers, 750 tonnes of lettuce and 7000 tonnes of peppers.

HOW ARE GREENHOUSE VEGETABLES PRODUCED?

A greenhouse is a building covered in glass, plastic or fibreglass. Most growing conditions can be controlled by the producer, often with the help of computers. Temperature, ventilation, humidity, light, water and carbon dioxide can all be increased or decreased to produce the best possible growing environment. Greenhouse growers often grow plants in a soilless medium, such as rockwool or sawdust. This minimizes weed and disease problems. Nutrients are given to plants hydroponically (through the water supply). It is important to ensure that the flowers are pollinated in a greenhouse. Greenhouse owners use electric vibrators or air blasts, or place bumble bee hives right in the greenhouse to make sure that pollination occurs.

Tomato seeds are planted in rockwool plugs. Rockwool is manufactured by heating certain rocks and spinning into a fibre. These plugs are quite light and provide oxygen around the roots of a plant even when well-watered. As the tomatoes grow they are transplanted, fertilized, pruned to one main vine and trained to grow up a piece of twine. Electric carts that run on the heating pipes between the row, much like a train, are used for picking, training the plants, and distributing the biological predators. Harvest begins 5 to 7 weeks after the fruit has set, just before the tomatoes start to turn colour. Tomatoes need to be picked carefully so they are not bruised. Bruised tomatoes have a shorter shelf life.

A tomato crop is seeded in November and grown for 12 months. The plant can grow a total length of 10 to 15m. The stems are trained to a height of three metres and the 'old stem' that has had the fruit and leaves removed is trained along the base of the plants. It takes 72 days for a tomato flower to develop into a mature fruit. In the summer, due to better light and temperature conditions, this process can take as few as 45 days.

It is possible to grow 2 to 3 crops of greenhouse cucumbers a year. Cucumbers are very sensitive to environmental factors so care must be taken at all stages of growth. Seeds are planted in plugs, transplanted very carefully to protect their fragile roots, fertilized, and watered. A mature cucumber plant can use 4 to 5L of water per day. Excess leaf growth is pruned to encourage the fruits to form. The cucumber vine is trained to grow up support wires. Cucumber harvest starts 2 to 3 weeks after the seedling were set out. You can tell when a cucumber is ripe because they are smooth with the ribs filled.

Sweet bell peppers are also planted into rockwool plugs, transplanted and pruned to maximize fruit production. The fruit will ripen 7 to 11 weeks after the fruit forms (depending on the time of year). Peppers are harvested when the fruit is at 85% of full colour.

WHAT DOES A GREENHOUSE VEGETABLE LOOK LIKE WHEN I USE IT?

Greenhouse vegetables look a lot like vegetables grown in the field. Because they are grown in more controlled conditions they are often larger and more uniform in size, shape and colour and contain little or no pesticides. Vegetables are an excellent source of vitamins, minerals and fibre. For example, a red sweet pepper contains three times the vitamin C that an orange contains.

WHAT HAPPENS AFTER THE GREENHOUSE VEGETABLE LEAVES THE FARM?

After greenhouse vegetables are picked, they are sold through three designated agencies. These agencies are all co-operatives made up of greenhouse growers. Most greenhouse products are centrally graded. This means the grower picks the product in the morning and ships to the Co-op where it is grade packaged and shipped to consumers in all parts of Canada and the U.S. In fact, 60% of all greenhouse vegetable produce leaves the province of BC for other destinations. The product is promoted in stores with posters explaining its nutritional value and quality.

WHAT CHALLENGES DOES THE GREENHOUSE VEGETABLE PRODUCER FACE?

Greenhouse growers realize that consumers are demanding vegetables grown with minimal pesticide use. For that reason greenhouse growers have been using 'biological predator' (good bugs) to eat 'pests' (bad bugs) for the past 15 years. For example: Aphids, a small green bug that feeds on leaf sap, is a pest of most home gardens and greenhouses. Lady bugs are a natural predator of these pests so growers release adult Covenergent Lady beetles in their greenhouse to attack and reduce the harmful aphid populations to manageable levels. Greenhouse growers are working to be 100% pesticide free in the near future.

WHO'S INVOLVED IN PRODUCING GREENHOUSE VEGETABLES?

• Greenhouse owner and manager
• Greenhouse workers
• Plant product inspector
• Packaging machine operator
• Trucker or transporter
• Vegetable wholesalers
• Retail store employees

Interesting Fact About Greenhouse Vegetables:

To ensure that crops that are grown in greenhouses get properly pollinated, many greenhouse operators place hives of bumble bees in the greenhouse. Bumble bees are ideally suited for this because they seek out every flower when it is at the best stage for pollen setting.

Contacts and other resources:

 

BC Hot House

BC Greenhouse Growers' Association

BC Vegetable Marketing Commission

BCMAL - Greenhouse Vegetable Information

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