What vegetables and plants do best in Canadian greenhouses?
Canada's greenhouse vegetable growers can grow produce throughout the winter. From B.C. to Ontario to Newfoundland, the most popular vegetables across Canada are; tomatoes, cucumbers, lettuce, bell-peppers, green/yellow beans, eggplants and various herbs and microgreens. Of these commodities, tomatoes, cucumbers, and peppers are the main greenhouse vegetable crops grown commercially by larger scale farmers in Canada.
Greenhouse gardening starts with greenhouse vegetables. Canadians have access to greenhouse vegetables that are not available outside of greenhouse production, including tomatoes, cucumbers and peppers. Canada's greenhouse vegetable growers produce tomatoes, cucumbers, lettuce, bell-peppers, green/yellow beans, eggplants and various herbs. Of these commodities, tomatoes, cucumbers, and peppers are still the main greenhouse vegetable crops grown in Canada.
Greenhouse vegetables are different from non-greenhouse vegetables because greenhouse vegetables are treated with extra care by the grower in a more climate controlled environment. The seed for greenhouse vegetables is started earlier so there is more time for root development before being hardened off and potted up. The greenhouse vegetables need to receive enough water throughout their lives but even more during flowering and fruit set periods so they don't drop fruit or flowers due to lack of water. Greenhouse tomato ripening times can be postponed by careful temperature control too, allowing sales long after outdoor tomatoes would have been eaten or smashed on the ground!
The benefits of growing plants and veggies in aluminum polycarbonate or high tunnel greenhouses are numerous. They keep plants from freezing in the fall, and warm over the winter due to improved insulation. They also take advantage of the "Greenhouse Effect" to allow sun to heat the air and ground in a greenhouse. This greenhouse heating effect further reduces greenhouse air temperature swings, meaning plants remain warmer at night and cooler during the day.
Pre-warming greenhouse air in spring can reduce greenhouse air temperature stress on young plants by protecting them from cool nights. It also speeds greenhouse warming in the spring since greenhouse sun light is already hitting greenhouse surfaces. This preheating can be done with high quality (meaning more expensive) propane or natural gas powered greenhouse heaters if an electrical power source isn't available for electric greenhouse heaters. However, using these kinds of greenhouse heating equipment typically require bigger investment.
Greenhouse ground cover materials are also very important to prevent plant roots from heaving out of the soil due to alternate freezing and thawing cycles that take place. Ground cloth is important to keep down weeds also.
Greenhouse greenhouse vegetables are usually planted four to six weeks earlier than outdoor vegetables. The greenhouse season for vegetables is also much longer, often up to sixteen weeks of growing vegetables depending on the greenhouse type and location.
There are many types of greenhouse designs that have been used successfully by Canadian greenhouse growers. This includes large high tunnel commercial greenhouses as wide at 38 feet and 100 feet long. Smaller hobby sized polycarbonate greenhouses are typica of backyard or weekend warrior gardeners. Many will use greenhouse shade cloth or greenhouse plastics as greenhouse covers, roofs over decks or platforms. Some attached greenhouses with different length walls and no walls at all such as our Lean to Grow greenhouse. Some greenhouses also feature sliding doors, self-opening temperature sensitive top and side vents and other accessories for irrigation, trellising and shelving.
The most important part about any kind of greenhouse construction is good ventilation (adding more vents), since plants need CO2 (carbon dioxide). The size of a greenhouse is important to consider. It will depend if you are growing basic food for your family or for a community or selling them to farmers markets. No greenhouse is set in stone, anyone can build a greenhouse and it will depend on the greenhouse if they decide to follow certain guidelines for greenhouse growing vegetables or not.
Building with material such as steel, aluminum or wood needs to be taken into consideration about the type of greenhouse you want and how much you are willing to spend on your greenhouse. The most common greenhouse materials used are plastic, steel frame or aluminum-framed polycarbonate panel greenhouses. Thickness of these greenhouse materials also matter depending on what kind of climate zone your greenhouse is located in.
All greenhouses need insulation to keep heat in during cold months and out during hot months. Insulation can be made from many different types of materials like poly plastic in 6 mil or 5 mil thicknesses. We sell various poly types and rolls to keep out UV rays and also prevent condensation for double wall inflated two layer plastic greenhouses.
Greenhouse vegetables are grown all over the world. The most important factor for greenhouse production is the climate. Different vegetables grow best in different climates. For example, tomatoes grow best in warm climates while lettuce grows well in cooler climates.
In Canada, greenhouse growers use various types of greenhouse materials to suit the climate in their region. The type of greenhouse vegetable production will also depend on what kind of soil is available and how much water the greenhouse can retain.
One of the most popular greenhouse vegetables grown in Canada is cucumber. Cucumbers thrive in a moist environment and do not like sandy soils. They are usually planted near a water source so that they can be easily watered. Lettuce, tomatoes and peppers are also very popular in greenhouses.
Leafy greenhouse vegetables such as: lettuce, celery, and cabbage do well in cold climates. They can be grown all year round and will produce a large crop within a short time frame. Root vegetables such as carrots, onions and potatoes grow best in greenhouse soil that has good drainage.
The greenhouse conditions influence the kind of greenhouse vegetables or flowers you'll plant. To ensure optimum greenhouse vegetable growth you need to know your greenhouse location's microclimate, sun exposure and choose varieties accordingly.
List of Common Greenhouse Flowering Plants in Canada
Carrots, beets and kohlrabi grow best in greenhouse soil that has good drainage.
As greenhouse vegetables need lots of water, greenhouse soils should drain well to prevent root rot.
- Seeds/seedlings: basil, beans, cabbage family (broccoli, cauliflower), cucumbers, eggplants, peppers
- Leafy greens: Asian greens (pak choi, tatsoi), lettuce varieties (romaine), spinach
- Root crops: carrots, beets and kohlrabi
Cucumbers are greenhouse vegetables that do additional well when they're trained on a trellis or netting. This reduces the amount of space the plants use up while exposing them to greater airflow. Saving space in a greenhouse is important.
When growing greenhouse vegetables, pests and diseases can be a challenge. To minimize problems, always use disease-free seedlings and inspect them often for any early signs of pests or diseases. Remove and destroy any diseased plants immediately. Also, keep the greenhouse as clean as possible and avoid over-watering. These practices will help to create a healthy greenhouse environment and reduce the chance of pests and diseases taking hold.
If you're looking to add some greenhouse vegetables to your garden, the ones listed above are a great place to start! For more information on growing vegetables in Canadian greenhouses, please visit Agriculture and Agri-Food Canada's website at www.agr.gc.ca. For more information on polycarbonate and aluminum hobby greenhouses or high tunnel commercial greenhouses, please review our greenhouse section, 2022 greenhouse buyers guide or contact us.