Where can I buy a prunus lusitanica about 7-8 feet tall in the Vancouver area, all I can find are much smaller trees, and we need a tree for privacy so do not want to wait for a small tree to grow.
There's a big difference between nothing and 8 feet tall. You may find a smaller one provides adequate relief, once in place. You might also consider erecting a pre-manufactured panel or trellis either with or without the new plant, to get the desired immediate effect.
Field grown laurels are rarely produced hereabouts...and then they are usually the oft-planted Otto Luyken sort that is not what you need. Container stock will be up to 3/5 gallon size, which might be what you've already seen. Best chance would be from a retailer who also does a lot of wholesale/landscape supply...several in Richmond would be the closest options for you in Vancouver...Bloom and Art's Green Tree have pretty good stock there. Only place you'd get a 7 footer is digging it out of someone's yard who doesn't want it anymore.
