Perfect conditions
Greenhouse growers say it’s a simple matter of controlling every variable

by Emily Leeson

Yes, the weather outside is frightful, but inside it’s quite delightful. Save for the low-grade cacophony of various machinery in the den Haan greenhouses in Lawrencetown, N.S., the atmosphere is downright pleasant. Despite recent school closures here in the Annapolis Valley due to heavy snow, freezing rain, and high winds, it’s business as usual for Luke den Haan.

The first crop of beefsteak tomatoes is already in – 17,000 double-stemmed, grafted plants. The cucumbers are going in today, rounding out some seven and a half acres of indoor growing space developed by this farm family. The facility is hard to miss; from Highway 101, two connected greenhouse units are visible. The shorter block was built in 1999, and the taller portion was added in 2012.

Though they are months ahead of field crop producers, Luke and his wife Jodi are a little behind schedule. The seedlings, supplied by a grower in Ontario, were a bit delayed. Once they’re all transplanted, a whole different set of variables comes into play, leading up to harvest time.

“The devils are in the details,” says Luke. “I learned very early on that you can manage the picking, the packing – this and that – but if you don’t have the tomatoes, none of that falls into place.”

He has plenty of experience to draw on. His family was involved in the greenhouse business back in the Netherlands, before his grandfather immigrated to Canada. Jac den Haan was originally aimed at Ontario, but when he arrived at Pier 21 in Halifax, he ended up tagging along with other newcomers who planned to settle in the fertile farmlands of the Annapolis Valley. Initially he took any agriculture work he could. He founded den Haan Greenhouses in 1963, and started making a name for the family as premier tomato growers in Atlantic Canada.

“He worked hard, my father worked hard, and now it’s just down to me,” says Luke.

The Netherlands has long been a leader in greenhouse growing. The country now has more than 12,000 acres under cover, and producers there continue to lead innovations and technological advances in the industry. This is because the Dutch only had so much space, and they had to make the most of it, says Luke. Their route to success involved finding creative ways of working within limitations – and that is precisely how he is running his business today.

The family used to have a garden centre on a small parcel of land along the old Highway 1 in Lawrencetown. In 1999, when they built the first half of their new block of greenhouses, they moved tomato production away from that site, with an eye to future expansion. At the new location there was room to grow, making it worthwhile to invest in infrastructure that would make the business more competitive. The garden centre was shut down in 2012 when Luke’s parents retired and handed over the reins to him.

The new greenhouses, designed by the Dutch company Venlo, are the fully-glassed, gutter-connected type. Ease of maintenance was the main reason for switching from the freestanding, poly greenhouses that stood at the old site. They were vulnerable to tearing, or ice and snow coming through the walls, recalls Luke. Loss of light was another weakness. “Every layer of plastic on the double poly is a loss of 10 percent of light, so you’re losing 20 percent of the light on a double layer plastic system,” he explains.

“Even in an ideal situation with plastic, you still have to replace it every three years,” adds Jodi.

“This is forever,” says Luke “This greenhouse was built in 1999, and it is just as good as the day it was built.”

With glass, maintenance is a simple matter of cleaning the inside with a spray solution every few years. Snow is melted as it gathers in the gutters, using the same hot water system that heats the space.

WOOD HEAT

Earlier generations of den Haans relied on steam heating, which allowed for no downtime when something went wrong. “In those old greenhouses, you’d have one hour, and it would be getting cold. They were complicated boiler systems too – Dad pretty much lived in there,” says Luke. “I feel so grateful that I don’t have to deal with that, because I can go away for a couple of days. I can change settings, reset things from home.”

Back in 1999, they started off with a propane system, but that was short-lived. “We built it, and the price of propane skyrocketed right after that,” says Jodi.

On top of the high fuel cost, the system did not supply quite enough heat for the operation. “It was cold, it was stressful,” says Luke.

Installing a wood biomass boiler dropped their heating costs by two-thirds. Within the past year, they’ve switched from wood by-products to hardwood chips that they produce on site. Luke purchased his own log truck and chipper, and added a fuel storage building. “It’s the same price, and three times the BTUs,” he says.

They now meet their entire heating demand with hardwood purchased from suppliers within an 80-kilometre radius of the greenhouses. “We spend $300,000 to $350,000 on just the logs themselves,” says Luke. “If we were buying oil, that money would flow to Saudi Arabia – the Middle East – but that money is now going into the local community. We take pride in that.”

The boiler heats a thermal storage tank with a total capacity of about a million litres, serving to buffer fluctuations in heat demand. The water, maintained at 90 degrees C, is circulated through the greenhouses as required. The entire system is electronically controlled, and Luke only has to make the odd late-night trip over to the site when something goes awry with the boiler. “It’s like flying a plane – I just put all the settings in,” he says.

The system goes through about 12 cords of wood a day during the winter, and there is some heat demand even in summer. “Greenhouses use a lot of energy all year round,” Luke says, explaining that cooler nighttime temperatures need to be moderated during the warmest months. Daily temperature fluctuations cause condensation on the plants, potentially resulting in mould problems. It’s better to have consistent heat. Drier conditions also ensure that the roots are constantly taking up water, which is how fertilizer is delivered to the plants.

“The moment you have your roots not taking up water, they start to die,” Luke says.

COCONUT HUSK

Today the planting crew comprises about 20 workers – half the number of employees on hand during peak harvest season. They are transferring the cucumber plants into tidy rows, nestled into coir – coconut husk fibre – imported from Sri Lanka. As a growing medium, it’s the most environmentally friendly choice the den Haans have found. It can even be repurposed after the crop is harvested – purchased by local gardeners who use it as a soil amendment.

Luke says that employing the right people, and focusing his own energies, have been essential to growing the family business. “Getting a mechanic and a labour manager was a big step for me,” he says. “My main job is growing the crop – looking at the water content, light level, climate computer, energy management, CO2 levels. Jodi looks after the selling of the product, so my job is to make her job as easy as possible, so she doesn’t have a mess to sell. It all starts right now, and if there’s a problem, then she has to deal with that problem all year.”

The den Haans put in one planting of tomatoes per year, and two plantings of cucumbers. Cucumber harvesting starts in mid-January, and the first tomatoes will be available in March.

By switching to tomato plants with double heads, the den Haans have more than doubled productivity. “Back when my father was growing, they were using one root stalk, one head, and they were getting 15 kilograms per square metre. Now we do one root stalk, two stems, and we get 63 kilograms per square metre,” says Luke.

Currently the greenhouses are producing fresh vegetables 10 months of the year, which is an impressive feat, especially amidst the snow and ice outside – but the den Haans have their sights set on year-round production.

“We want to maintain 800 watts of light per day, every day, but in the wintertime we’ll probably have a day with 50 watts of light, which is nothing, so if I’m able to top that up with artificial lighting, I will be able to achieve all that,” says Luke. “That’s where the future is.”

“Lights for year-round production will mean that we aren’t in and out of the market,” Jodi points out.

LIVING ECOSYSTEM

In addition to controlling heat and light to create the ideal environment for plant growth, the den Haans have to decide what other elements of the natural world to let in, and which to keep out. A high level of control is an essential defence against some of the worst-case scenarios of modern agriculture.

“Things like that Romaine lettuce problem – we don’t get things like that,” says Luke. “We have the roof to keep the bird waste from falling on the plants, we can control all of the labour as they go through the rows, and there’s no E. coli coming in on the fertilizer.”

Even with glass walls, some pests make their way indoors. Back when he was working for his father, Luke had his first experience with Spider mite – a common threat to cucumber plants. One Friday he noticed a small spot of infestation, but not wanting to spend his weekend spraying, he said nothing and let it go. “We came in on Monday, and that greenhouse was just white – little spider webs all over the place,” he remembers. “The plants were toast. I’d never seen anything like that in my whole life.”

Now he doesn’t let anything fly under his radar. In addition to Spider mites, the main adversaries of the cucumbers are thrips and whiteflies. For the tomatoes, it’s primarily whiteflies. Instead of seeking an environment devoid of insects, Luke is just striving for the right balance.

“We create a little living ecosystem – good bugs, bad bugs,” he says. “That’s kind of the secret to it, having a good balance, right in the middle – the sweet spot. Not too much of either. If you don’t have any bad bugs, there’s nothing for the good bugs to eat.”

Even as the cucumbers are being planted, the greenhouse workers are preparing one of the bio-controls they use. Luke shows off a handful of the little thrips-hunting insects he’s introducing. Already in place among the tomatoes are parasitic wasps known to lay their eggs inside the eggs of the whiteflies and hatch out in place of them. “You don’t start your control when you have a problem,” he says. “The first day of planting is when you start your control.”

The den Haans also bring in specially-bred bees for pollination. They’re delivered by Purolator on a regular basis. “We have to keep adding them,” says Jodi. “In the summer the bees will fly out the window.”

With all these variables controlled, Luke says he expects 100 percent success from his crop. Once picked, the produce will head immediately into the packing and processing building they built recently. Kept at 15 degrees C, this is where the cucumbers will be wrapped in plastic to reduce moisture loss, and the tomatoes will be boxed in cartons. From there, the vegetables go to Loblaws and Sobeys stores across Atlantic Canada. The den Haans have their own truck for deliveries to small stores, restaurants, and farm markets along the Valley.

Even on planting day, Luke is thinking about those transactions with customers. Foresight and vigilance are essential in this business. “It’s like the tomato and cucumber plants – if you don’t know what you’re doing, it can quickly become a big bushy mess, but the secret is to nip things off at the bud before they become a big problem,” he says. “We just have to make sure that everything is always perfect.”

(Emily Leeson is a writer and the editor of the Grapevine newspaper, a community-driven arts and culture publication serving the Annapolis Valley. She lives in Wolfville, N.S.)