"If you see the leaves curling, on the edge, or you see brown on the edge and the tree looks like it's stressed and you haven't seen one of our crews there, we would really appreciate your help," said chair John Coupar.
The city has planted 15,000 trees in the past five years and these saplings are especially prone to dry weather as they haven't established strong roots yet.
City workers set up slow-release water bags around the base of 500 young trees in early June in an effort to stave off any negative effects from the heat.
"There are two very small holes in the bottom of the bag and it just drips right into the ground. It's a good way of watering and not wasting water," said arborist Bill Manning.
The city is asking members of the public to fill the green water bags if they notice an empty one outside their home.
There are approximately 140,000 trees in Vancouver, and the city plans to add 150,000 new trees by 2020.