A fence is quicker than a hedge.

The only thing I can think of is clumping bamboo, and even that takes a while. The previous owner of our house put in a bamboo "hedge" to screen our backyard from the neighbor's two story house. The hedge is supposed about seven years old, and along most of its length it is two stories high. I wish I knew what variety it is, but since we didn't plant it, I have no idea! Also, I am zone 8... so I have no idea if bamboo can do zone 4.

Take a look at columnar buckthorn. My parents had it between our backyard patio and our neighbor's driveway. It made a nice hedge and is relatively narrow.

If I had remember what they used, I would have used it in my yard as well, but I planted dogwood instead. my loss could be your gain ;)

How about shades or curtains or interior shutters?

Not trying to be facetious, but a good solution until something green and growing gets going. 4' wide limits your choices. Don't know where you are in MN, but Bachman's seems to be one of the biggest players in the Cities/Metro area and they'd have some recommendations for your requirements, I'm sure.

Columnar Buckthorn (Rhamnus Frangula) aka Alder Buckthorn, European Alder, Fen Buckthorn, Glossy Buckthorn, as well as Rhamnus Cathartica (common Buckthorn) are on the Wisconsin and Minnesota invasives list - not to be purchased, planted, or spread.

How about a bracket trellis over the top of your window on the outside? Plant a five-leaf akebia (vine) and you'll have a screen over your window. Akebia is easy to train and trim -- get a 3 gallon pot and you'll be in business in one year. It's easy to cut off as the tendrils just wrap around things. Meanwhile, the trellis gives you some screening. It's the fastest, easiest solution for the space.

See examples in the link (I have one of these over my garden gate).

Here is a link that might be useful: bracket trellis examples

Would an awing work on the top of your window?

We used the Aussie willow for the outer rows in our windbreak. Talk about fast growth- 8-10 feet in single year. Trim back and it will bush, giving thicker & better screening. In the long run, plant something that's going to be thicker right to the ground. I don't know if it'll grow in MN, but how about good old privet?

"Columnar Buckthorn (Rhamnus Frangula) aka Alder Buckthorn, European Alder, Fen Buckthorn, Glossy Buckthorn, as well as Rhamnus Cathartica (common Buckthorn) are on the Wisconsin and Minnesota invasives list - not to be purchased, planted, or spread."

Wow, I had no idea. Thanks for the info :)

You might want to look at Manhattan Euonymus. It"s a fast grower with dark green leaves. 6 to 8 ft. tall and about 5ft. wide. It reqires full sun . It is a great hedge and excellent for privacy

Wow! Thanks, great ideas! I'll have to put some more thought into this! Amy

Good luck on your privacy fence project. I came across this post as I'm doing my own research to build a privacy fence too. Thinking of going with a cedar fence, but working out the details still.

Unless you have the bathroom window open a lot during hot weather you could use translucent glass that admits light while obscuring visual details. If that is not adequate maybe you could even use one-way glass, like some people have on their cars.

Euonymous 'Manhattan'-evergreen and our three plants are now about 7'-8' feet high, thick, and providing excellent screening. It has a really pretty green leaf and small, inconspicuous flowers. I really like it for the purpose of screening a couple of windows from our neighbors and the street.

Well, there is screening windows, and there is screening bathroom windows. And whether you already plan to use curtain/shade but just want some additional fuzzing-out of you and your neighbor's views of each other (from either direction).Depends also on window location and angles and whether you may spend time at night (lighted interior/dark outside) naked in front of the window! I wouldn't rely on some plants for that kind of privacy that close to another house. That's when you might need glass block or other translucent material as noted above. Also whether the window otherwise has a good view, located so you can leave window uncovered much of the time, provides key light for an adjacent room, and so on, that would lead you to preserve clear glass at all costs. So it's a balance between being able to go in and out of your BR without fear, and preserving windows when you can.