OK, I just found a potential tree for you! How about a Black Alder tree? I was researching Nitrogen Fixing trees and found this, then I thought about you :) http://advancedtree.com/tree_blackalder.htm "The Black Alder grows vigorously and has a central leader tendency. Its leaves remain dark, glossy green late into the fall. The Alder converts nitrogen from the air into its own fertilizer, producing a growth rate of up to 6 feet per year. With a total growth of 60ft by 20 to 24ft, it can be used as a screen or shade tree. (For Screening and windbreak plant trees 6 to 10 ft. apart.) The Black Alder needs plenty of moisture to get established and will grow in heavily compacted soil if a moderate amount of water is available. Alder will grow in extremely wet conditions." It grows in zones 4-7. I'm thinking of planting this in my side yard to replace a giant old Spruce that was uprooted during a Nor'Easter last month. I need some fast privacy and the soil is pure clay. 25 feet wide is perfect, and 60 ft. high isn't bad either. You will have a hard time finding something that fits your height requirement that doesn't require maintenance, so this seems to fit the bill best.

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.

Chinchette, Could you mean viburnum odoratissimum 'awabuki', i.e. mirror-leaf viburnum? I have a few of these as screeners and really like them. Very carefree. I let them grow tall and have their natural shape; read: no maintenance. I love the shiny leaves, and even the tiny flowers and red berries are nice. The birds and squirrels appreciate them. I would describe it as a moderate grower, but mine are in quite a bit of shade. Anything you plant will take a couple of years to get to the size that will give you good screening. Even bamboo. I think I would invest in plants. Cuttings will add on about an extra year for most things. Bamboo is a great idea too, and the clumping ones have very little to no maintenance. Anna

I was just going to ask this- then noticed I asked this and forgot! Passiflora isn't quite hardy here, well not in this exposed location... but thanks for the idea. Any other ideas? I'm still wishing for grapes and hops but it is pretty dry. Silver lace vine would also work but every time I buy them they seem to winter kill - even though they are supposedly hardy here. Maybe if they weren't in the pot over winter would help!