With that width restriction, and with you wanting access through the "Alley", it's NOT going to be easy to plant trees. Since that's a property line, are you aware that any part of a tree with roots on your side of the line that extends over the line then belongs to your neighbor? He can cut it off at the property line and dispose of it - he just can't toss it back over the line to you. So it sounds as though your "shade" trees need to be tall, thickly leaved, and about four feet wide, and I am not sure that such a plant exists! I think you are looking at evergreen trees. Just to list the requirements - you want to move wheelbarrows, etc., through the passage, which needs a minimum of 3' for a path next to the house wall. But you need to be able to walk freely, and not worry about bumping into the wall of the house, so let's make it 3'6" at a minimum, 4' if feeling generous, for the pathway. That leaves 3' or 3'6" for planting space. You can trim up the trunks of trees, removing the branches, to a height of 6-8', so you can walk under the limbs of the trees, and have only the trunks to contend with next to the path. However, for this to be done with regard to the health of the tree, the tree needs to be somewhere around 15' tall. If you aren't going to look for permission from your neighbor to annually go on his property and trim your trees, you are looking at very narrow, columnar trees, that will grow no more than 4-5' wide - the width of the planting space plus the width of the block wall. You might, if you planted the trees right at the edge of the pathway, get away with a 6' width. To fill a 40' length, you will need 8 trees, maybe 9. This project is NOT going to be cheap! And I am not familiar with trees that grow in a columnar fashion, so I can't make any recommendations for especially narrow ones - all the ones I can think of would be at least 10-12' wide. I am not saying you can't do it, but I am saying it will NOT be easy. You might do better to plant a tree near the SW corner of the house, in the back yard - I am assuming there is one there? - and get shade from a tree that way, which would give partial shade to the "Alley". To shade the entire wall, you might, indeed, do better with a large trellis, but put it up on the house, and not on the wall. If you position it a foot or so away from the wall of the house, you will get shade, and be able to have some air circulation there too. Your passageway then would run next to the block wall, and you would be able to make it 4-5' wide, not 3-4'. You could plant vines, both evergreen and perennial, and also trees like pyracantha, that lend themselves to espalliering. Roses might work, also. Any work that needed to be done, in terms of trimming back wayward shoots, tieing in to fill up the trellis, and trimming to keep windows clear, could be done, and cleaned up, from the passageway, so your neighbor wouldn't be involved. This might not give as much shade as you wanted, but would be MUCH more do-able.

I actually have some photos, I just realized, though they are taken from the porch so are into the canopies, not capturing the full tree profile from the ground. Both were taken in September. Pterostyrax, circa 4 years old: Heptacodium, circa 12 years old: My neighbour has a forest pansy redbud and though I was jealous when she got it, in the intervening years I have come to regard it with indifference. I think you have to know what you like in a tree, especially when you are seeing them up close. The redbud to me is somewhat sterile, and stagnant. It doesn't move a lot with the wind, the flowers are meh (maybe this one isn't situated well), there is no insect or wildlife interaction, and it has kind of a "designer plant" vibe to me - maybe that would not be the case with species varieties. I also cannot abide trees that have 4 days of flower interest and then nothing - our street tree is a flowering cherry that I could say goodbye to without regret tomorrow. For up close tree-planting, you have to consider things like bark, foliage form, foliage movement, fragrance, the development and emergence of buds and seeds... all things that you will be looking at every day. I find that these two trees are holding my interest, and in the case of the heptacodium increasing it, every year. Your needs, and thus your trees, will be different, of course. That said, the paperbaRk maple that Whaas has suggested is also a good option, and maybe easier to get and hardy. By the way, the other thing you have to come to terms with on a small lot is rapid tree turnover. Like, maybe 20-30 years, if that. We've been here nearly 20 years, and I am already taking out shrubs and conifers that I planted early on, and I suspect even the heptacodium will have to come down within 10 years. If that side yard is yours then you have more space than I do, but other than that your house and yard are uncannily like mine (straight walk to centre door, porch with two windows; only diff is I have a peaked roof where you have the dormer). Karin L

One of California's native Live Oaks is probably what you want. Don't know which one and there are several to choose from. May take 10-20 yrs. before it gets big enough to do you any good. I'd suggest plant one of those where you want it on one side of your yard and on the other a temporary/faster shade solution to be cut down once your oak has grown enough. Either : A. Plant a trio of Arizona Cypress somewhat close together (these will block a portion of your view eventually)and locate table near them. They should provide shade much quicker than oak and the color is nice. You may decide to leave one or two. They are fairly long-lived and relatively clean, drought/disease resistant, etc. Excellent choices in themselves. or B. Plant a Mimosa tree : These will get 8-15' high and spread out nicely. They will drop flowers and are considered a trash tree with a short life, but they would match exactly what you wanted for providing a tree with low spreading canopy to shade a picnic table and hummingbirds love the flowers.

5x7 seems awfully small. The roots of anything you plant will quickly fill that area and begin to grow into the surrounding soil, under the paving. We have a Trident maple in our yard, planted as a tiny seedling about thirteen years ago. It was selected from a collection of volunteers from a gorgeous mother tree and we hoped that the gene pool was a strong one. We crossed our fingers for a great natural infrastructure or beautiful fall color.....we got both. The seedling was about two feet tall when I transplanted it into a bark based potting medium to grow for a year before planting it in our side yard. It was about three feet tall when planted in the ground. It's now approx. 30 feet tall by 25 feet wide, with a diameter of 14 inches. (I asked my husband to go out and look.) We plant directly into hard, red Alabama clay soil with no irrigation under two to three inch layer of mixed wood mulch that we increase the radius of every year as the tree shades out more of the lawn. It does get watered during periods of serious drought, maybe a handful of times a year, at most. I live in Northern Alabama (6b-7a), with coldish winters and I consider this a pretty sunny part of the country.....certainly not gloomy. There are no visible surface roots and no driveway buckling. I asked my husband about the mature Tridents where he works and he said that there are no pesky surface roots. He's the Director of Horticulture and Landscaping at a local university in our city, so notices those kinds of things. However, all bets are off regarding behavior of any kind considering that very small planting site.