To really be helpful, you should post this in the CA Gardening forum. I think only bahia is CA-based here. Also, we need more specifics:

What part of Northern CA are you in? Some of us are frost-free and others are not; e.g., you could be in Sunset zones 13-17, which is a very wide range.

What's your exposure? Sunny, shady, or in-between? Does it get hot west-facing sun or gentler east-facing sun?

What's the soil like?

How much water will you be giving it? Which leads into: What's going to be around it? You'd want to group plants of similar water requirements together.

This is especially true since the rumor is that there will be a 50-85% water REDUCTION, mandatory, by the State of CA if we don't get some substantial rains in the next few months.

Hello, Edel, welcome to the world of gardening, and to the Landscape Design forum. As a new gardener, your life will be easier if we suggest something 'easy' for your conditions, but in order to do that, the extra information requested by jkom is needed.

If you visit the California forum, type "screen" into the SEARCH feature and you will probably find many discussions on this subject.

One idea: if you don't mind shaping a shrub a couple of times a year, take a look at Tecomaria capensis, or Cape Honeysuckle. The ferny leaves are dark green, and it's almost always in bloom. It doesn't require much water once established, and hummingbirds will fight over the tubular orange flowers. But it is very important to do the maintenance or you will have a gangly bush throwing out long whiplike branches; nicely trimmed, it's a beauty.

Yes, but I have never seen bamboo look good without water, and in year 3 of our drought, unless the OP has unlimited access to well water it probably won't work as a good screen.

I can second tecomaria in the right siting, you can get the orange flowered (most common) or yellow flowering types. Very fast grower, too! Tends to need iron, at least in my garden.

Actually, a good many bamboo species are exceptionally drought tolerant once established - Fargesia, a clumping variety, is just one. These are just large ornamental grasses and most appreciate conditions similar to those preferred by their lower growing cousins - sun to part shade, well draining soils (bamboos can get root rot if in too wet a situation) and minimal fertilizer.

And it is important to remember that drought tolerance is not immediate. Even very xeric or low water use plants will require some initial period of regular watering to become well established.

I'm sorry, gardengal, I don't mean to get into an argument with you. But I still don't think bamboo is the best choice here. Yes, it's drought-tolerant, but in certain areas of Northern CA they just won't look any good without more summer water than some other plants would require. In Contra Costa Cty it isn't at all unusual to see Asian restaurants with bamboo in outdoor planters, and in summer they look pretty pathetic without regular irrigation.

We in CA have to face the fact that we are pretty much high desert country. This is the time to establish new plants as even in a drought year like this, we are getting some rain - it's raining right now, and scheduled to shower occasionally over the next 5 days.

But there are some plants that once established in the winter/spring, can really get through our bone-dry summer/fall season with very little water and still look good. I water very little compared to most gardeners, and I've seen a big difference between plants that barely survive 6 mos. without help, and plants that still look good (or even thrive) on the same very minimal watering.

I'd pick tree roses, oleanders, nandina, rhaphiolepsis, rhamnus, coleonema, and a whole bunch of other plants over bamboo. However, I live in the Oakland hills with very few frost days, and conversely very few 80+ degree days, so what I use might not be appropriate for the OP.

I didn't say it was the best choice, only that it shouldn't be discounted solely because of its reputation as being an overly aggressive spreader. The OP expressed an interest in it but was concerned because of that reputation. And there are a number of species that are considered quite drought tolerant once established. Several Bay area nurseries grow and recommend them. Any plant grown in planters or containers - drought tolerant or not - is going to require supplemental irrigation. That is just the nature and physics of container culture. Plants established in the ground present a far different situation. And establishment takes more than a single growing season in any case. Planting now - in what could pass as your rainy season - will not guarantee any degree of establishment or drought tolerance for the coming summer months.

There are literally dozens of plants that could work in this situation. I've attached a link on California waterwise planting that includes several rather good lists that also include a lot of native choices. I will say that based on my experience (and I've gardened and designed in SoCal as well as in the PNW, a repeating summer drought area), some of these plants are not nearly as drought tolerant as others. But it does make a good starting point. Just scroll through the nonsense at the top of the link until you get to the plant lists.

Here is a link that might be useful: California drought tolerant planting

Gee, "blocking the window" is still way too vague for me, even beyond the zonal issues.

In addition to light and soil conditions, can the OP give more info about the layout--spacial issues, how far away is house, how high is window, what else is on property, etc, before recommending species? Because you would first need to identify a general "form," or several options, that would give the right effect--is it to be narrow, tall, billowy, how deep, full-height screen, dense scren, eye-distraction screen, or whatever.

I have to admit, my first thought is to get window coverings for your own window(s). No worries about how quickly it will grow, the perfect angle to hide it, water use, whether you can keep it alive as a first time gardener, etc. Then you can concentrate on what else you want for your exterior spaces. I am guessing that if you are in NoCal, you probably don't have a lot of space to work with, and I'd hate to have privacy be the only consideration when rushing into plantings that you may regret later.

Plants possibly are not the only solution to provide privacy. You might not need to establish a complete screen, but have some opening.

I would first do a layout of the space, like elevations and distance. I had such a problem once and could not find any plants which would have grown fast enough to provide privacy soon. I designed a blind towards a (very nice) neighbor, who from all side windows and even his front porch and entrance could observe my back patio. With that 9 ft blind - and you can do it artistically - I gained a new room for entertaining and barbecue.

Bernd

Arborvitae shrubs are fast growers and used as screens/buffers and are much more attractive then italian cyprus, and good for all zones.

But we still don't know what kind of space the OP is working with or willing to give up for a living screen. If we're talking virtually no yard space with livingroom windows or a patio door opening out directly in the face of the neighbor, a set of drapes or vertical blinds would be the easiest/quickest/best solution... at least until the arborvitae really put on some size. :-)

Can I assume that you can also see into the neighbours window as well? How much time do you spend each day doing this? Do they spend more time looking at you? Perhaps not cooking while naked would solve the prob.

There is some good gardening advice in this thread that I can use now. I have been moving to California recently (San Diego area) and starting to build a garden. I'd like to grow tomatoes and other vegetables. Bamboo and flowers on the other side of the garden would also look good. Do you have any further recommendations?

I think that podocarpus (fern pine) would be good there, because it is a pretty narrow tree. It's wider than Italien Cypress, but it is pretty narrow. I think you need an evergreen, because you would want the screening all year long. You probably don't need to have something as high as a two-story house to put between you and their window. It just needs to be somewhere in between the height of the two windows.