l008com
Full Access Member
I'm planting three of these "mini" maple trees in a row in my back yard. They are going to divide my long skinny yard in half, while giving the middle of my yard that usually burns in the summer, some much needed shade.
Now if you look at my yard (this is a May photo, theres a LOT more sun burnt grass right now), you're first thought would be - this is a perfect space for some trees!

But my beautiful lawn hides a secret. From what I can tell, the whole level part of the back yard was made by stacking up huge broken chunks of concrete from old buildlings or bridges or who knwos what. Then lots of un-compacted ASPHALT was dumped on that to level it! Yes, ASPHALT. Then they threw some amount of dirt over that. Except right in the middle, where they formerly had a swimming pool. So there was a giant ring of gavel around a circle of sand.
After years of trying to will grass to grow out there, I finally spend one summer digging and digging and digging. Digging up all the sand, digging up all the gravel, and digging up SOME of the asphalt. But not all. I just didn't have the time to dig out ALL of that material. I then threw down a lot of fresh top soil and the grass has been growing great for the past 3 years or so! The asphalt is porous because it wasn't compacted. So its not like a driveway or walkway material.
This is what it USED to look like:

You can't really see the asphalt, its all under the surface. And its in a huge area, more than the whole circle that was the pool.
Here's a photo from the year I started digging it all up. In some areas, it was a thin layer a few inches thick. In some areas, it was much thicker. In one area (near the fence), my cousin kept digging and digging and smashing and picking and was never able to reach the bottom of the asphalt. The area I dug up was much larger than this, this is just a random picture I took during the process.

So, all of that is just background.
Here's the situation. I have three Shantung maples growing in pots, about 2-3' tall and I'm planting them, as previously mentioned, in a row across the yard, dividing the yard in half. That means two, if not all three of these trees are going to potentially be in the asphalt zones.
My first thought was, I'll just dig the holes really deep, then backfill them once I make it through any asphalt I hit. That way the tree can sink roots down deep while the rest spread out horizontally above and below the asphalt layer. But doing some research on how maple tree root systems grow, it seems like nearly everything is going to be above the asphalt. And that is not ideal! Its hard to estimate how much top soil I buried all of that with. Some areas might have a foot or more, but other areas might only have a few inches.
So, what are your thoughts? I mean the real solution is to start digging up the whole lawn again, and I'm not doing that. So i GUESS the real solution is to just stick to the plan: deep holes, back fill, plant trees, hope for the best. Hope that the asphalt is brittle enough that the roots can just grow through through it. And it was very brittle. I would use a pickaxe when I dug it up, but I wasn't really prying with it, I'd just stab it and it would shatter. Then I'd shovel up the pieces.
If I had thought ahead, I would have grown my big sunflowers down in that area the last few years to let those roots try to break up the asphalt more. Oh well, too late now.
Here's the first photo again, which is fairly recent and more or less what it looks like now... but with three red dots in the approximate spots where the trees are going.

So if you have any thoughts on all this, let me know.
Also if you're wondering, I specifically went with the Shantung (Acer Truncatum) because it looks more or less like a green maple, but only grows to about 25 or 30 feet. So they'll shade the yard just the right amount but won't shade solar panels on the house if I get them again.
Now if you look at my yard (this is a May photo, theres a LOT more sun burnt grass right now), you're first thought would be - this is a perfect space for some trees!

But my beautiful lawn hides a secret. From what I can tell, the whole level part of the back yard was made by stacking up huge broken chunks of concrete from old buildlings or bridges or who knwos what. Then lots of un-compacted ASPHALT was dumped on that to level it! Yes, ASPHALT. Then they threw some amount of dirt over that. Except right in the middle, where they formerly had a swimming pool. So there was a giant ring of gavel around a circle of sand.
After years of trying to will grass to grow out there, I finally spend one summer digging and digging and digging. Digging up all the sand, digging up all the gravel, and digging up SOME of the asphalt. But not all. I just didn't have the time to dig out ALL of that material. I then threw down a lot of fresh top soil and the grass has been growing great for the past 3 years or so! The asphalt is porous because it wasn't compacted. So its not like a driveway or walkway material.
This is what it USED to look like:

You can't really see the asphalt, its all under the surface. And its in a huge area, more than the whole circle that was the pool.
Here's a photo from the year I started digging it all up. In some areas, it was a thin layer a few inches thick. In some areas, it was much thicker. In one area (near the fence), my cousin kept digging and digging and smashing and picking and was never able to reach the bottom of the asphalt. The area I dug up was much larger than this, this is just a random picture I took during the process.

So, all of that is just background.
Here's the situation. I have three Shantung maples growing in pots, about 2-3' tall and I'm planting them, as previously mentioned, in a row across the yard, dividing the yard in half. That means two, if not all three of these trees are going to potentially be in the asphalt zones.
My first thought was, I'll just dig the holes really deep, then backfill them once I make it through any asphalt I hit. That way the tree can sink roots down deep while the rest spread out horizontally above and below the asphalt layer. But doing some research on how maple tree root systems grow, it seems like nearly everything is going to be above the asphalt. And that is not ideal! Its hard to estimate how much top soil I buried all of that with. Some areas might have a foot or more, but other areas might only have a few inches.
So, what are your thoughts? I mean the real solution is to start digging up the whole lawn again, and I'm not doing that. So i GUESS the real solution is to just stick to the plan: deep holes, back fill, plant trees, hope for the best. Hope that the asphalt is brittle enough that the roots can just grow through through it. And it was very brittle. I would use a pickaxe when I dug it up, but I wasn't really prying with it, I'd just stab it and it would shatter. Then I'd shovel up the pieces.
If I had thought ahead, I would have grown my big sunflowers down in that area the last few years to let those roots try to break up the asphalt more. Oh well, too late now.
Here's the first photo again, which is fairly recent and more or less what it looks like now... but with three red dots in the approximate spots where the trees are going.

So if you have any thoughts on all this, let me know.
Also if you're wondering, I specifically went with the Shantung (Acer Truncatum) because it looks more or less like a green maple, but only grows to about 25 or 30 feet. So they'll shade the yard just the right amount but won't shade solar panels on the house if I get them again.

