First, these are not MY choices - they are recommended by the California extension service for the poster's area. Generally, these bodies take into account problematic species and are not inclined to suggest or recommend known invasives for a specific area. It is always appropriate to remember that invasive characteristics are typically determined by regional and climatic factors and are not universal in their application. As a major agricultural state and with a great deal of public and private undeveloped land, California is very aware of invasive species and rather proactive in their restrictions. And "fast" is a relative term and also carries with it the caveat that a fast growing tree often displays unfortunate charcteristics that have other, less desireable outcomes. Shade is not instantaneous and patience is a huge virtue when it comes to planting and gardening. If instant shade gratification is required, it often makes much better sense to select a more mature, larger sized tree that has a moderate or slower rate of growth than one that will rapidly achieve too great a size or exhibit weak wood or other drawbacks typically associated with rapid growth.

Thanks! I've heard of the purple hyacinth vine too, but is there any possibility of getting it NOT as seed? Or scarlet runners? Even something that will make it partway thru the summer would be better than nothing. I was thinking about tomatoes in a couple of big containers -- hoping to find some Celebrity -- but I hadn't thought of growing them up the wall. My main criteria for back there is "green," so getting some tomatoes (or ANY tomatoes) out of it would be a bonus. Will tomato vines live through the summer here, even if they aren't setting fruit? I'll check out okra, and sunflowers might be cool. You've got me thinking outside the box now. Heck, maybe I'll try some corn back there, or some other type of bean or pea. Direct sow and see what happens. Again, if it doesn't do "all that well" or gets fried or eaten or makes a bit of a mess back there I won't be heartbroken. I just want a bit of a screen that won't be a nightmare to get rid of later. One other option would be something viney that is quick and long-term but controllable -- if it would stay on the wall behind the roses and not try to eat them, that would be completely acceptable. I just don't want cat claw or something horrific like that.

Hey there, I think a couple shoots of Clematis Ligusticfolia var ligusticfolia (common name 'Western White Clematis') will set you right up. It grows bushy and huge, climbs easily, covers itself in sweet-scented white blooms that turn to fluffy seed heads that will stay through the winter, it's fine in full sun (or part sun, or shade, or anywhere, really), it's hardy in USDA zones 4-8, is disease resistant and likes moisture (it usually grows near stream beds and such). AND it's a North America native plant! Sounds crazy but it's true. Here's some links to prove I'm not just making it up: The Alberta Nursery where I first heard about it: http://www.bowpointnursery.com/online-catalog/vines/western-white-clematis/ A comprehensive description of it on the University of Texas wildflower site: http://www.wildflower.org/plants/result.php?id_plant=CLLI2 USDA native plant information: https://plants.usda.gov/core/profile?symbol=CLLI2 Description on the Montana native plants site: http://montana.plant-life.org/species/clematis_ligu.htm Description on the Pacific Northwest Wildflowers site: http://www.pnwflowers.com/flower/clematis-ligusticifolia British earth-hugger site with details on propagation and care: http://www.pfaf.org/user/Plant.aspx?LatinName=Clematis+ligusticifolia And here's an image I found of it on a site called Rooted in California http://rootedincalifornia.blogspot.ca/2010_04_01_archive.html

A wisteria would do, if it's sturdy enough, (wood stalks about 4+ inches thick in diameter would. Anything less, and the Wisteria would demolish it with it's trunk like base. A silver lace vine would also do, but it doesn't have showy flowers like a wisteria does. My third thought would have to be Carolina Jasmine, it's fast growing, showy flowers and doesn't take over like English Ivy does. It's hardy enough for Ontario's winters too. Good luck!