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Science Insider

Chasing Fireweed

- May 1, 2020 - Alison McAfee - (excerpt)


Fireweed offers a premium, late-season nectar flow for beekeepers who can handle its unpredictability

In 1920, when Frederick Dundas Todd, British Columbia’s first provincial apiculturist, toured the remote valley near the village of Telkwa, he left with the awe of a prospector who had just struck gold. Telkwa is located in a sparsely populated region of BC, just several miles southeast of Smithers and about as far north as the southern tip of Alaska — too far north for sustained agriculture.

“I left the valley with the feeling,” Todd wrote, “that I had seen a region that some day will be the heaviest honey producer of the continent, a district where a man could put down all the hives he could personally manage in one spot and get a big crop from them all.”1

The crop he was referring to is fireweed honey. Fireweed, which is one of the first plants to colonize after logging or burning, can be marvellously productive. Todd illustrated this with an impromptu flower dissection: On a drive through the mountains, he stopped to pinch the flower’s delicate petals, splitting it in half to see what reward is offered by its nectaries.

“Just look at that blob,” he wrote, “a big drop of nectar caught at the bottom of the stamens and pistils; it must be itself a load for a bee.” But despite lucrative yields at around 200 lbs. of water-white honey per hive that year, a few years later, honey production from the same region was “practically a failure.”

What gives? To this day, the fireweed crop is frustratingly unpredictable, and Telkwa never did become the “heaviest honey producer of the continent.” Unlike staple flows from robust, invasive plants like the Himalayan blackberry or Japanese knotweed, fireweed has the fickle flow of a sensitive, native plant. Add to that the fact that it thrives in remote alpine regions accessible only via rough logging roads, which also happen to be prime grizzly bear territory, and chasing fireweed starts to look like a risky gamble.

“We cannot find any indicators that [the fireweed] will yield nectar other than putting hives there,” says Liz Huxter, a long-time beekeeper in Grand Forks, BC, where she runs her business with her husband, Terry. Some beekeepers place sentinel hives in the mountains, and move the rest up if they start putting on weight. But the Huxters’ approach is to chase fireweed only when the expected opportunity cost is low.

“When it looks like the valley is going to be really hot with little chance of nectar flows, we try putting some hives in the fireweed,” Liz says. The fireweed flow is late in the season, from mid July to mid August. When they can catch it, it offers a beautiful honey that sells at a premium, owing to the effort, uncertainty, and perhaps an element of alpine terroir.

One reason why yields are difficult to predict is because it depends on many different environmental factors.2 Early springs are bad, because the plant invests too much energy in new shoots which may just be wasted in a subsequent cold-snap. Cold, wet springs are bad, because it is harder for the shoots and leaves to develop, causing the plant to burn through its energy stores and be less able to invest in sexual reproduction (flowers) later on. Low soil moisture in the summer is bad, because osmotic pressure is necessary for both blooming and nectar secretion. But too much soil moisture is also bad, because the plant will disproportionately invest in foliage, rather than flowers.

According to the late John Davidson, a former botanist at the University of British Columbia, a heavy winter snow paired with a mild spring, or light snow paired with warm rains in May or June, should tickle the fireweed’s fancy.2 The melting of a deep snow pack can provide moderate soil moisture well into summer, but in its absence, summer rains should do the trick. Unfortunately, it’s not uncommon for those conditions to be met, and to still have a poor fireweed crop.

“To try and predict a good honey flow with fireweed is a bit of a toss up,” says Rudi Peters, a beekeeper in Terrace, BC, not far from Telkwa. He has been targeting fireweed for almost a decade and agrees that ground water and summer rain are important, but that in his experience, ambient temperature is the dominant factor. “You don’t want temperatures above 24 C [75 F],” he says. Otherwise, “the nectar will dry out during the midday, allowing only for a couple of hours in the morning for collection.”

Fireweed is such an important flow in Canada and the Northern United States that some researchers have tried to better understand what triggers nectar secretion. In 1989 and 1990, J. P. Michaud — a then-graduate student at Simon Fraser University, now a professor at Kansas State University — conducted a series of experiments to see what made fireweed tick.

In the field, Michaud observed that average ambient temperature and the amount of sunshine correlated best with nectar production.3 When he varied the temperature of potted plants in the laboratory, he found that ….