Features Efficiency Energy
Shining light on a production problem

In an effort to keep pace with fierce competition from producers in sunnier, southern climates, an innovative greenhouse operation in Ontario has made a big move to grow tomatoes all year round.

Great Northern Hydroponics in Kingsville, Ont., built a new 14-acre greenhouse that uses high-density light fixtures to extend the growing season and significantly increase its production. Completed in 2011, the greenhouse uses approximately 7,000 light fixtures equipped with high-pressure sodium light bulbs.

Guido van het Hof, president and general manager of Great Northern Hydroponics, says expanding to year-round production from the conventional timeframe of nine months was a logical next step for the company.

“If we stand still, then we move backwards,” says van het Hof, referring to the intensifying competition from greenhouse tomato producers in the southern United States and Mexico. “And producers there have natural advantages over us in terms of climate, lower energy dependency and high natural light concentrations, resulting in an extended growing season.”

These competitive advantages are significantly impacting the market in a negative way for Ontario greenhouse tomatoes. During the conventional greenhouse season in Ontario, the crop is harvested from March until December. The volume of domestic production declines in the fall and winter months. As the Ontario production drops, van het Hof says producers in the southern U.S. and Mexico are able to move into the market. What’s more, they can capitalize on higher prices because the overall supply is usually diminished during this time period.

“In the spring, once we come on with significant volumes again, we have to buy our position back on the shelves. And that’s a problem,” says van het Hof.

To offset these advantages and to enhance its competitive position, he says the company needed to respond. “We had to come up with better technology and new, innovative solutions on how we’re going to offer retail stores the same thing,” adds van het Hof.

Great Northern borrowed a page from producers in northwestern Europe who faced a similar situation 10 years ago. They installed lighting technology to compete with growers in Spain, Morocco and the Canary Islands. “We took that technology and we emulated it here to our circumstances and our climate zone,” says van het Hof.

After September, the daylight diminishes to the point where there are not enough light units to sustain production through the next few months. Great Northern uses the lighting system to add light in the morning and then again in the afternoon or early evening, thereby increasing the day length to a certain amount of hours. The number of supplemental lighting hours increases as the days wind down to the shortest day of the year in December.

As the daylight increases again, the supplemental lighting hours are reduced. “That way we can almost balance out the total amount of light units that we dose to the crop during the course of the year,” says van het Hof.

The lights can also be used if the natural light levels fall below a certain intensity level during overcast days.

In addition to installing the lights, Great Northern also had to be innovative when designing the greenhouse. The high-pressure sodium lights emit a lot of heat. As a result, a buffer needs to exist between the plant heads and the bottom of the light fixture. To accommodate this buffer, the company built a seven-meter structure – approximately a meter and a half higher than a conventional structure.

Two curtain systems – one for heat retention and the other for light abatement – were also installed.

“You can imagine with this capacity of light installed that in the coldest part of the year – and you have really clear nights – you don’t want to project a lot of light to the surrounding area,” notes van het Hof. “So we have the ability to close a top curtain that has a 99 per cent light retention capacity. The walls are equipped with that as well.”  

The double-curtain system also increases the energy efficiency from a heat perspective inside. And because heat rises, vertical fans have been installed to take the warm air generated by the lights and re-distribute it to the bottom of the crop.

“We have a constant, maximized air flow and we have no temperature differences from a vertical aspect. That gives us a better growing plant,” he says.

Great Northern is using the new greenhouse to grow two varieties of tomatoes – beefsteak and cocktail tomatoes. Workers were picking the first winter crop produced in the new structure in late January.

“We’re very excited. This is really a first trial for us and so far it’s working out at least as expected, if not better,” says van het Hof.

The crops are grown using an intercropping method to allow for continuous production year-round. Under the system, five crops are planted over a three-year period. Young crops are planted as the older crops mature.

Van het Hof says they’re achieving a substantial yield increase over the conventional system. “If you measure it from 12-month production figure, we’re targeting about a 40 per cent increase in yield output.”

The lighting system is one of many innovative projects Great Northern has completed over the past few years. Faced with shortages of predators to control whitefly, it worked to establish its own dicyphus colony. It has also installed a state-of-the-art, 12-megawatt cogeneration system. The province gets a clean and reliable electricity source, while Great Northern Hydroponics gets the heat and CO2.

For van het Hof, the innovations are part of doing business in the highly competitive industry.

Noting that producers in Mexico still have some logistical hurdles to overcome, he says those barriers are offset by diminished energy input costs, significantly lower labour costs and the production potential offered by their geographic location.

While quality has been questionable, van het Hof says they have been investing in technology and retaining experts.

“We need to stay alert, vigilant and innovative in order to stay ahead of the curve,” he says of the competition. “We never stop thinking and I think that it is crucially important. We’re always looking to raise the bar.”