We have 2 ft (60cm) high retaining wall and 2 ft behind the retaining wall is a 4 ft (1.2m) high fence. Naturally there is backfill with 5/8" crushed stone directly behind the wall. This backfill goes back 1 ft (30cm), but only goes to a height of 9 inches (23cm) from the top of the topmost retaining wall block.
We would like to plant trees at 6 ft (1.8m) apart (centered between fence posts) for some privacy from our neighbors. We live in a 3 story town-home so the trees have to be reasonably tall (10-12 ft [3m]?) to be effective.
We would like to plant 3 Japanese Maples (Blood Good) along the wall around 6 ft apart (and a Golden Raindrops in the larger corner). We want to buy the trees when they are already at a height of around 10 feet with a rootball of around 2 feet.
As you can see, the roots can grow outwards, backwards (under the fence), downwards, but will be blocked from growing forwards. My question is what can we do to maximize the success here.. or is it a lost cause?
Edit 1, 2016-08-21
- We live in Seattle, USA.
- There is a french drain behind the wall with crushed stone and geo-material for drainage. In the picture you can see the drain protruding out of the wall.
- We can certainly protect the fence from the soil using water proofing material, thanks for the suggestions on this!
- Our thoughts were the tree roots would grow under the fence (backwards) as far as they wanted, out to the sides and downwards. Naturally there would be no roots growing forward and this was our primary concern.
- It's not clear from the photo but the neighbors yard is dirt behind the fence. I did not realize the concrete they've spread would make the pH of the dirt unsuitable. Thanks for this info - is it a hopeless pH issue?
Edit 2, 2017-06-26
We went ahead and did it anyway and it's working out well so far. I've built an irrigation system into the wall, and under the lawn. This picture is from a month ago, but now that it's summer they grass, plants and trees are thriving. Let's see how it goes in the long term...
Edit 3, 2020-08-05
The trees are happy and vibrant and have grown well. In the end it was a successful project, I'm glad I took the risk and planted them in that space.