"They're really to try and nurture those roots and keep them moist so the tree will actually reach down into the ground as opposed to spreading the roots on the surface," said Howard Normann, manager of urban forestry and specialty parks for the park board.
The green slow-release bags can hold 15 gallons of water and wrap around the base of the tree. There are two holes on the bottom that drip water and can last anywhere from nine to 18 hours.
Normann says there are five water trucks that go around the city, five days a week in double shifts and inject water into the roots.
"But we find sometimes in dry years that's not enough," said Normann.
Last year the city planted 11,000 new trees and are hoping to plant a similar number this year.
Normann is confident the public will get onside with this new initiative as it benefits the city as a whole.
"I think people in Vancouver are very passionate about their trees and they look for ways to help us. A majority of people — we are hoping — will buy into it, go out, fill up the bag and hopefully help that tree grow for a long healthy life."
To hear the full interview with Howard Normann, listen to the audio labelled Thirsty trees.