Re: Hydrangea with yellow, wilting leaves
Going partly by appearance of soil surface around it, including low plant growth it appears the planting site may be too moist and/or leached. Dig around to see if the soil is sodden beneath the surface. If soil is instead too dry beneath (common here at this time of the year) then should also become apparent when poking around in it - you may be greeted by unexpected dustiness. And take some steps to address infertility, leaves are pale regardless of burning. Don't know what is available in Vancouver but here optimum situation would be soil sampling and testing, with assistance from Cooperative Extension network.
After possible moisture and very likely infertility issues addressed, as with most other garden plants results liable to be much enhanced by mulching the soil around the hydrangeas.