This is probably the most difficult question. How to go up buy not out. And only 4 inches soil wide at the top and down a ways. So you will have to start with very young plants.

Then the problem of the neighbor's house being close. So if you were to get some 'standards' established their upper spread could cause dissension.

I would look for a near thornless 15ft climbing rose that is sold in a band (narrow container). Zephrine Drouhin comes to mind. Would require pruning maintenence as will anything with height.

A few years back Sinai posted an added height solution. It was a wood fence. At intervals a 4x4 was attached. It looked to be 2 ft. taller than the fence. Near the top of each 4x4 a hole had been drilled that allowed a heavy chain to pass thru, which was allowed to drape (not touching the top of the existing fence) before passing thru the next 4x4 post's hole. The climbing rose canes were to be attached to the chain creating the privacy height. Maybe this avoided any local rules about fence height?

I am a fan of Trachelospermum jasminoides for narrow drought spaces. But it would need support as it doesn't cling.

Here is a link that might be useful: Hoovb's narrow screening part I

Thanks for those insights, iris_gal! You're suggestions are nice looking, but seem to either require too much maintenance for my plan, or have flowers that will drop a lot of petals. I'm tenuously leaning toward the dreaded bamboo, after further research - of course, only the clumping varieties! Not sure if this will be where I end up (I'm one of those people who love to over research things before I make a decision, so goodness only knows where I will eventually end my search!)

Right now, these are the varieties Im thinking about:

-Dwarf Malay variegated bamboo (Bambusa heterostachya)
-Murray Island Bamboo (Schizostachyum)
-Alphonse Karr
-Golden Goddess
-Fargesia dracocephala 'Rufa'
-Thamnocalamus tessellatus
-Bambusa multiplex
-Umbrella bamboo

Anyone have thoughts on the matter?

I adore bamboo. Thanks for those names on 'clumpers'. I was given some black bamboo and warned not to put in the soil. Use a large pot I was told. Best advise I ever got.

Looking at the photo, unless your neighbor stands on a ladder inside his house, he'll have a hard time looking into your yard.

This being California, maybe he does stand on a ladder and look into your yard.

A short wrought iron "fence topper" with a vine growing up to and along it would be the most narrow solution that would allow you free movement along the side of your house. Unless the bamboo is a very vertical grower, it's going to be slapping you in the face and dropping crap into your neighbor's yard, which he may not appreciate.

If you don't like that pink wall, cover it up with Parthenocissus tricuspidata, common name Boston Ivy (it's not Ivy). It's easy to manage.

Unfortunately, there are no plants like the one you need (everyone in Southern California needs that plant!)
The problem with bamboo is that it is really messy, and it will not grow straight up, it will lean into your narrow walkway.

If your neighbor doesn't mind, you could put a series of long terra cotta planters on top of the wall with a drip system and plant asparagus ferns.

I am guessing that the wall is the legal limit for a permanent structure and you can only go higher with a temporary support of no more than 2 feet. If that is so, I would suggest you add what is approved and plant two Clematis armandii. They are evergreen and will cover the whole wall easily within a couple of years, require no care, and bloom in the spring, with enough fragrance for the whole neighborhood. Al

espalier? I could have sworn the OP asked for "low maintenance".

Actually, I think they are very low maintenance. They are quite easily kept flat due to their form. You don't need to fuss with them as is the case with most espaliers. My three plants take less than 15 minutes per MONTH to keep in line during the growing season. When the root system gets well established (maybe after 5 years or so) they can bounce back with vigor. But they tend to grow flat and up rather than out. So I just cut off 3-4' at one time from the top when they reach that stage.

Only 2-3 plants would be needed to cover the 20' section.

Edited to add some photos. This full shot is of a plant that has not been pruned recently, because it was in bloom. It shows how the branches are still rather flat against the supporting wall.

This post was edited by Gyr_Falcon on Wed, Nov 27, 13 at 17:02

These photos show the branching form.The top part shows an unpruned branch. As you can see, it by nature does not have a lot of width. The bottom section of the photo shows how the form of the side branching is almost completely to the sides, so the branches stay rather flat against the support. Yes, there are some branches that will send out growth into other directions, but they are the exception for this plant, rather than the growth habit that is normal for most shrub plants. So there is not a lot of pruning required to remove them.

Now, I am not saying you cannot get this plant to form a round shrub with pruning. But it is rather unique in that when it is used as an espalier, it naturally wants to remain flat due to its flat branching pattern.

The OP said they have 12" to plant NET. They clearly said it looks like more than 12" but that 8" has a footing underneath. The picture clearly shows 20" of dirt between the wall and sidewalk. Compare the dirt width to the 16" long cement blocks.

They did NOT say they had 12" of dirt, 8" of which had the footing underneath.

I think I got that from another post on the thread and didn't check and recalculate from the OP's information. Moot point, it seems. The original poster doesn't seem interested in the thread anymore.

Gyr,

Even if the OP doesn't come back to participate, you have helped other gardeners. I was very interested in your recommendations. I saved the info and sent links to a friend looking for a solution to a similar problem. Your pics and plant info are saved in my permanent reference folder.

Thanks for the info and pics!

Yes, Gyr, very helpful post. I had been deliberating on using it this past summer, and choose Pittosporum Heterophyllum instead, but seems grewia would have been an excellent choice.