Robot-raised lettuce

COALDALE, Alta. — At first, people thought the massive greenhouse being built east of this southern Alberta town was destined for marijuana production.

The timing seemed right, 18 months ago, when talk was rampant about cannabis legalization.

Today, an estimated one million plants flourish under 5.5 acres of glass.

They are lettuce plants — leafy, luscious and as lovely as lettuce is ever liable to get.

The operation is called Whole Leaf, and it markets 19,000 to 33,000 heads of lettuce per day, depending on the season and its available sunlight. That is eight to 10 million heads of lettuce each year.

Most of them are labelled as Inspired Greens. They are the lettuces, roots attached, that are now seen in grocery stores across Western Canada and the United States Pacific Northwest. A wider distribution, to Eastern Canada, the U.S. eastern seaboard and Texas is in process, said Rindi Bristol, senior director with Whole Leaf.

Construction is underway to double the size of the growing space, expected to be ready in 2019.

“We’re also going to be the largest greenhouse lettuce producer in North America once this side opens,” said Bristol, indicating the mirror-image greenhouse being built on the current building’s southern side. “And we’ll probably have the most annual production in North America.”

The hydroponic, automated systems within the greenhouse are state of the art and one of a kind, using robotics, sensors and a unique, proprietary system of heating, cooling and humidification.

Robotics are used to seed and later transfer the growing plants to larger spaces so they can reach the desired size of about 225 grams of leaf weight, depending on variety. Each plant is in a separate peat pot and separate slot within a gutter system so its leaves never touch surfaces that might affect quality.

The entire facility is automated to the point where no human hands touch the plants until harvest and packaging for shipping. That’s how such a large operation can function with one head grower, two assistant growers and about 50 other employees.

The number of varieties of lettuce available can come as a surprise.

Bristol said there are four main varieties most popular with consumers, “but we are trialing extensively just because this is the only greenhouse like it in the world, so we’re trying to figure out exactly what our plants need and what our climate is.

“Right now I think we probably have 30 different varieties and 25 different combinations…, which is way too much, so we’re trying to scale that down and really figure out what the market wants and what the consumer wants and what grows best for us.”

Whole Leaf is owned by Saskatoon-based Star Group and an additional group of Saskatchewan investors. Southern Alberta was chosen as a location for the $60 million operation because of its many hours of sunlight, the second highest in Canada, and access to water delivered through the St. Mary River Irrigation District. It lies along Highway 3, a main east-west route, and is close to other major highways north and south.

“It’s easy access to the U.S. population and it’s a quick hop to Calgary as well, which is a major hub of economic activity,” Bristol added. “We’re right in the heart of where we need to make sure that we can hit all of our customers. People are well aware that we’ve got a pretty unique facility right here in southern Alberta.”

Water is key to the operation, given that lettuce is 98 percent water.

“The quality of the water and the taste of the water can really affect the taste of your plants,” said Bristol.

She said it takes one to 1.5 litres of water to grow one head of hydroponic lettuce. In the outdoor operations in California and Arizona, it takes more than 80 litres per head because of flood irrigation.

When the irrigation district shuts off the water delivery system in winter, Whole Leaf uses large water tanks and also collects condensation. The water is cleaned and filtered before flowing back into the gutters for use by the plants.

“Pretty much the only water that leaves the greenhouse is actually in plant material. Everything else is getting recycled back through the system.”

The greenhouse also has a co-generation plant to capture waste heat and carbon dioxide.

A hybrid lighting system includes LED (light emitting diode) and HPS (high pressure sodium), which provide additional ultraviolet light and heat. Lettuce prefers temperatures of 18 to 21 C.

The greenhouse is lit for about 18 hours a day in winter, with amount adjusted with the solstice so plants get as much natural sunlight as possible.

Production is higher in summer. Bristol said the slowest variety growing now takes 44 days “from seed to sleeve”, while the fastest variety takes 36 days. In summer, growth accelerates so a fast variety can be ready in 27 days from seed to salad.

As the plants mature, the automation system moves them through the greenhouse to the eastern end where harvesting occurs. Fertilizer is all water-soluble and there is no need for pesticides.

“We don’t use any pesticides, mainly because we have complete control over our climate as well as our inputs,” said Bristol.

Once harvested, the lettuce is cooled to 3 C, which puts it into dormancy ready for shipping. Upon arrival at the store, retailers are directed to display it at ambient temperatures without misting.

“We’ve been working really hard with the stores to change their methodology,” Bristol said. “Because we have the roots and the peat and this mass that comes with it, we had a lot of stores that were actually drowning out plants.”

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