It's raining elm seeds in Edmonton

Edmonton gardeners may be tempted to add vacuums to their landscaping arsenals as elm seeds rain down across the city. 

The pesky, papery-brown pods are piling up in yards and gardens by the truckload.   

It's a "banner year" for the seeds because the city's elm trees are in distress, said Jim Hole, owner of Hole's Greenhouses and a certified arborist.

"We've been kind of inundated with seeds everywhere in the city," Hole said in an interview with CBC Radio's Edmonton AM. 

"The trees go through periods of masting … and normally when they're under a bit more stress, they'll tend to shift more toward production of seed." 

Elm trees typically begin to overproduce elm seeds following a drought, Hole said. 

"It's not like they're on their last legs but it's nature's way of making sure they pass on their progeny and their genes if things go sideways, weather-wise."

Hot, dry conditions, a lack of precipitation, and the spring onslaught of road construction can all put added stress on the species.

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"It all has an impact on the trees," Hole said. "Somehow we think that tree roots grow like carrots, straight down. They don't.

"They spread out laterally so anytime the soil is disturbed and roots are removed then the tree is stressed out."  

'They're going to need some help'

Hole said the fluffy seed pods can become a problem for gardeners. If they manage to germinate, the seedlings can quickly take root in gardens, lawns or any crack or crevice with suitable soil. 

"That little innocuous-looking elm seedling that pops up, people think, 'Ah well just leave it. It's fine.' But next thing you know, they're growing around the house," Hole said.  "They want to become a tree, so they can become a pretty weedy species. And you want to make sure you clean that up." 

Water is the magical thing.- Jim Hole

Edmontonians can ensure trees on their property remain healthy with plenty of water. Aerate the soil and irrigate the roots if necessary, Hole said.

"The trees are getting to the point where they're going to need some help," Hole said.

And if homeowners are really desperate to save their trees from drought-like conditions, they should consider scrapping their lawns — which will compete with trees for scarce moisture in the soil. 

"Water is the magical thing," Hole said.