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What Does 24 Hours Of Light Do To Plants?

What Does 24 Hours Of Light Do To Plants?

The midnight sun is great for growing veggies, but not so good for the trees in the forest
By Elaine Anselmi
Jun 14
2017
From the June Issue Issue

By early March, day is equal to night and staff at Arctic Farmer Nursery in Yellowknife have started seedlings and readied the greenhouse for growing season. By early April, when the hours of total darkness are few, a layer of sparse green has covered the tables, and sprouts peek over the edge of colourful hanging baskets that line the ceiling.

During the longest days of summer, watering the crop is a full-time job. “The sun hits that wall first,” says co-owner Carine Pattin, pointing to the west side of the 5,000-square-foot greenhouse. “It moves along through the day. The plants you started out watering are dry by the time you get to the other end.”

They’ll water three times a day, and sometimes again late in the evening. The plants also require a lot of trimming. Because of the endless light, plants grow fast and become leggy, rather than filling out.

It makes for long days, says Pattin, but that’s the reality of growing in the North. The nursery will supply bedding plants to homes and businesses across the city, and colour the streets with baskets of flowers. Sweet peas, haskap berries, vegetables and herbs start off in the greenhouse, to be transplanted into gardens throughout the city.

Yellowknife’s rocky terrain is tough for gardening, so baskets, pots or beds built into the ground or above are the fix for taking advantage of the short-lived season of relentless light. 

It takes surprisingly little expertise to reap bushels of
kale and spinach, veggies and herbs from a Northern garden—just a lot of water and, depending where you are, bags of imported soil. 

In Iqaluit’s community greenhouse, a temperature regulation system had to be installed to fend off the intense heat that comes with endless sunlight. In the summer months the temperature inside the all-glass structure can climb to 50 C, despite dropping to around zero at night. Similar greenhouse facilities have been built or repurposed across the North—an old arena in Inuvik or geodesic dome in Naujaat, Nunavut. 

In Dawson City, the soil situation is more favourable, but the short summer still plagues gardeners. “You are growing things inside longer than other places in Canada,” says Katie English, the city’s community garden coordinator in early April. “I have started a lot of my plants already, some at the end of February and all throughout March and April and I will not be able to plant out until the first week of June, which is typically our last frost date.”

But once the plants are outside, they’re speeding through the natural growth cycle, constantly doubling or quickly going to seed. You have to be vigilant about clipping the tops of herbs and other plants to encourage new growth below. “I think we Northern growers are working so hard to extend our seasons but at the same time, with the 24-hour light that speeds our plants through life cycles, we are also working hard to slow some of them down,” says English.

This isn’t quite the case in Northern forests.

The North isn’t known for its lush wilderness. There’s the treeline, which cuts through the northern portion of the Yukon, down half of the Northwest Territories, and through the southwest corner of Nunavut. But even below the treeline, the forest is mostly made up of spindly conifers with a few aspen, poplar or birch peppered in. The heartiness of trees improves as you move farther south into better soil and less dramatic seasons of light and dark.  

“You’d think with 24 hours of light—or close to that—productivity would be much higher. We see that a little in vegetables, but gardens are very different than the natural forest,” says Stephen Biggin-Pound, a forestry instructor with Yukon College. “There are different factors that [living things] need. Light is one for sure, but there’s also water and nutrients and temperature.” Limited and poor soil is an issue in the North—one reason being the cold temperatures most of the year inhibit the decomposition of organic matter that holds nutrients. And the sky offers only a small amount of rain, as evidenced by the harsh forest fire seasons in the last few years. “Greenhouses perfect that balance for nutrients, water and light,” says Biggin-Pound. “Our wild ecosystems aren’t really able to maximize that light availability.”

When fungus met algae

Lichens—sometimes colourful and feathery; sometimes dull and brittle—cover rocks, trees and soil across the North.
And it’s a love story for the ages.

Lichen is made up of fungi and algae. The latter photosynthesizes sunlight (working around the clock during summer months) for the team, while the fungus component absorbs water and nutrients. During winter, the whole organism goes dormant. Writes biologist Jeff Hollett: “I like to think of lichens as fungi that have converted to solar energy.”

A lone icon

The semi-arid cold climate in Yellowknife means it’s hard up for hardwood trees, even one of Canada’s most iconic: the maple tree. But there is at least one. A single maple tree was planted some years ago outside the Monkey Tree Pub in the city’s uptown. And it’s still standing, offering just a few square-metres of shade while the sun
circles overhead.