[kimberland30]

My husband and I are starting to build a low retaining wall around a large oak tree in our front lawn. To get a circle, we went up the trunk of the tree approximately 4', and out 5' using landscape paint to mark where the front of the wall will go. Knowing that the tree trunk is not a perfect circle, we knew we'd have to make some adjustments.

My question is that when we dry placed the first row of blocks, it looks very off balance. The more we play around with them, the more "damage" we do. Do we need to just keep playing around with them until they look like they are in a circle, or is there a better way to create a perfect circle under an oval-ish tree?

Any help is appreciated!

 

[gma2rjc]

Use a garden hose to form the shape you want, then mark it with the paint.

Be sure you don't make the soil inside the retaining wall too deep over the trees' root system, it may not get enough water.

 

[kimberland30]

We'll try a hose and see how it goes.

We are covering the exposed roots with about 2" of a compost/soil blend. If we need more fill, we'll put down gravel before the soil so we keep drainage at a maximum around the tree.

 

[gma2rjc]

It doesn't seem like 2" would be a problem anyway. I've seen people put 12" to 18" around a tree and I've been told that shouldn't be done.

Here's an idea that came to mind as far as creating a perfect circle around your tree (if the hose doesn't work). If you have a hoola-hoop, and it would fit around the tree, try cutting it and let it lay at the base of the tree. Anchor it in place and take your measurements from that.

 

[kimberland30]

That is a brilliant idea!

When I went home during lunch I tried the hose, but that didn't work very well. I happen to have a hula hoop in my office (a left over from a picnic we had - just so you know I don't normally keep hula hoops in my office LOL) so I'll take that home tonight and try that.

I've seen websites that recommend no more than 6" of soil should be within 5' of the trunk of a tree. I don't know how accurate that is though. I figured we'd be okay with a couple inches, plus about 3" of mulch on top.

 

[kimberland30]

The hula hoop idea was a great one, unfortunately the one I have won't fit around the trunk of the tree.

I laid out the wall again last night and created a jig to put in between the blocks so they are perfectly spaced, but then I ended up with a foot more in front. When I went to even it up, I had a foot more on the side.

I guess I'll have to keep playing with the positions and spacing to get it "just right". Sometimes I hate being so OCD.

 

[Scuba_Dave]

I usually draw a circle - maybe meaasuring out the same distance around the tree. Then I just put the blocks down & move them slightly in or out. Should be about a few hour job

 

[47_47]

Trees have a flair at the bottom of the trunk. If you bury the flair, you will girdle (strangle) the tree.

Lay out the wall on the driveway. Make a 2 piece template for the wall (cardboard?). Place the wall around the tree using the template as a guide.

I think you are trying too hard to get a perfect circle for the wall. Nothing in nature is perfect.

 

[downunder]

I may have missed this- I did re-read- but is the fill going inside the circle or outside?

It doesn't seem like 2" would be a problem anyway. I've seen people put 12" to 18" around a tree and I've been told that shouldn't be done.

Be sure you don't make the soil inside the retaining wall too deep over the trees' root system, it may not get enough water.

The concern is not a water issue, but that you will smother the roots. A very high percentage of a tree's feeder roots are in the top twelve inches of soil. (This is one reason that tree damage is often done with herbicides. You try to kill weeds in your lawn while spraying over the tree's feeder roots and the tree absorbs the herbicide as well.) One of the main reasons it is hard to get shrubs and groundcovers to grow under mature trees is that the tree will suck up the water first, creating the double-edged sword of "dry shade." I know that seems strange, but compare the idea to the big dog at the feeding bowl. Tree wins!

If you bury the flair, you will girdle (strangle) the tree.

Sorry, 98% false. Simply burying the flair will not strangle the tree. Piling mulch, soil, etc against the trunk will encourage rot and pest damage. If, possibly, the soil is so deep, so tight and heavy that it presses against the xylem and phloem hard enough to prevent water and nutrients from passing through, then maybe this thesis could be true. That said, there is a definite danger- in another context- of girdling roots. That is, a root that comes out from the root flair and for some reason turns and goes around the root flair instead of out like a good little root should. Consider that roots can break up sidewalks and pavement and it is easy to see how they can strangle the cellular highway from root to tree. But not likely with a couple of inches of soil against the trunk.

Please feel free to verify this with your local university ag dept.

 

[kimberland30]

I usually draw a circle - maybe meaasuring out the same distance around the tree. Then I just put the blocks down & move them slightly in or out. Should be about a few hour job

Trees have a flair at the bottom of the trunk. If you bury the flair, you will girdle (strangle) the tree.

Lay out the wall on the driveway. Make a 2 piece template for the wall (cardboard?). Place the wall around the tree using the template as a guide.

I think you are trying too hard to get a perfect circle for the wall. Nothing in nature is perfect.

Thank you both! I ended up playing around with the blocks and got it as close as I could - finally telling myself that it will not be perfect and "good enough" is okay with me! I actually got about 1/3 of the wall up yesterday and hope to get more done tonight (if the rain will hold up until later!).

I may have missed this- I did re-read- but is the fill going inside the circle or outside?

The fill is going inside the circle.

The concern is not a water issue, but that you will smother the roots. A very high percentage of a tree's feeder roots are in the top twelve inches of soil. (This is one reason that tree damage is often done with herbicides. You try to kill weeds in your lawn while spraying over the tree's feeder roots and the tree absorbs the herbicide as well.) One of the main reasons it is hard to get shrubs and groundcovers to grow under mature trees is that the tree will suck up the water first, creating the double-edged sword of "dry shade." I know that seems strange, but compare the idea to the big dog at the feeding bowl. Tree wins!


Sorry, 98% false. Simply burying the flair will not strangle the tree. Piling mulch, soil, etc against the trunk will encourage rot and pest damage. If, possibly, the soil is so deep, so tight and heavy that it presses against the xylem and phloem hard enough to prevent water and nutrients from passing through, then maybe this thesis could be true. That said, there is a definite danger- in another context- of girdling roots. That is, a root that comes out from the root flair and for some reason turns and goes around the root flair instead of out like a good little root should. Consider that roots can break up sidewalks and pavement and it is easy to see how they can strangle the cellular highway from root to tree. But not likely with a couple of inches of soil against the trunk.

Please feel free to verify this with your local university ag dept.

I was told by a specialist not to go all the way up the trunk (thus burying the "flair") because of root rot. I do not plan on doing that. There are several roots that are already covered, and have been for several years with no serious consequences.

There used to be black edging around the base of the tree, and the area was filled in with soil, compost and mulch. I basically took out the edging and am putting in a retaining wall, and adding about another 2" of compost blend and 3" or so of mulch. The actual "flair" of the tree will not be covered at all.

That would be the correct thing to do...right?

 

[downunder]

I have just noticed that I used flair instead of flare. Flare is correct.

Just out of curiosity, how large/old is this tree and why the ring?

I was told by a specialist

Do you mean an arborist? I would suggest that you web search, go to the library, call your local county extension service office or other reputable source and learn the difference between "root rot" and damage to the flare. If the "expert" did not explain that, he did a disservice to you.
Root rot is a fungus caused by roots staying too wet. Think of trenchfoot, EEWWW.
It is possible to cause rot around the collar, truck, etc by having mulch and/or soil against it. Roots are supposed to be in the ground. The trunk is not. That simple.
I always take my hand and pull back the mulch and soil- just an inch or two- to make sure to avoid this problem.
An extra point, mushrooms growing near the trunk are usually an indication of a root problem, often in a low, shady site. You don't always have both, but something to keep in mind.

 

[47_47]

Do you mean an arborist? I would suggest that you web search, go to the library, call your local county extension service office or other reputable source and learn the difference between "root rot" and damage to the flare. If the "expert" did not explain that, he did a disservice to you.
Root rot is a fungus caused by roots staying too wet. Think of trenchfoot, EEWWW.
It is possible to cause rot around the collar, truck, etc by having mulch and/or soil against it. Roots are supposed to be in the ground. The trunk is not. That simple.
I always take my hand and pull back the mulch and soil- just an inch or two- to make sure to avoid this problem.
An extra point, mushrooms growing near the trunk are usually an indication of a root problem, often in a low, shady site. You don't always have both, but something to keep in mind.

Thanks downunder for the correction and explaination.

 

[Leah Frances]

The best 1 hour job starts with 1.5 hours of thinking. Try laying it out with stakes/rope or the hose before you do any more heavy lifting.

Take a step back and eyeball it after you set up your stakes - trust your eye above any measurements. Look at it from the front and the side. If it looks right to your eye it doesn't matter if it's off here or there by a few inches.

Is the tree symmetrical? Is the crown and drip line centered around the tree trunk? Do you want the raised bed to be centered under the tree. If the tree 'leans' it will make things look funny no matter how perfectly centered you make the bed - trust your eye.

Here's a method I used before for putting a bed around a tree

- Measure a distance (use a rope/chain/tape measure/rake handle and pick any fixed length you like) away from the tree trunk at N - S - E - W (the cardinal points don't really matter - you could use 12 - 3 - 6 - 9 around the clock) .
- Keep the measurement 90 to the tangent.
- Drive a stake at each compass point.
- Repeat at NE - SE - SW - NW or 1:30 - 4:30 - 7:30 - 10:30
- if you connect the dots with some string you end up with an octagon - but that is easy to 'round out' with a garden hose.

TRUST YOUR EYE!

 

[kimberland30]

I have just noticed that I used flair instead of flare. Flare is correct.

Just out of curiosity, how large/old is this tree and why the ring?


Do you mean an arborist? I would suggest that you web search, go to the library, call your local county extension service office or other reputable source and learn the difference between "root rot" and damage to the flare. If the "expert" did not explain that, he did a disservice to you.
Root rot is a fungus caused by roots staying too wet. Think of trenchfoot, EEWWW.
It is possible to cause rot around the collar, truck, etc by having mulch and/or soil against it. Roots are supposed to be in the ground. The trunk is not. That simple.
I always take my hand and pull back the mulch and soil- just an inch or two- to make sure to avoid this problem.
An extra point, mushrooms growing near the trunk are usually an indication of a root problem, often in a low, shady site. You don't always have both, but something to keep in mind.

I'm not sure of the age of the tree...these homes were built in 1960 so I presume the tree has been here since then, possibly even before that. The tree is about 8' around and it sits on a slope in our front yard. The reason for the wall is because of the slope, everything we put there (soil, mulch) shifts into our yard. We installed black plastic edging around the tree, but that was starting to fall apart, and the mulch (2" or so) was going over top of the edging.

Yes, it was an arborist that came out. There is one huge root that has already cracked our sidewalk, and is making it's way to our driveway and front porch. He said it would be okay to cut this root to prevent more damage - without harming the tree. We briefly discussed the area around the tree since it already had plants and ground cover and edging around it. I mentioned that I'd like to eventually build a low retaining wall around the tree so that I could level off that area, and he didn't bring up any issues with my plan - except that we should go out approximately 5' from the trunk (which we did), and not cut any major root systems (which we didn't).

We've never had mushrooms in our yard, but thank you for that tip.

Here is what it looked like before. We made a circle around the tree and took out the flower beds that went from the tree to the driveway, and from the tree to the front door (the area in the second picture to the right of the sidewalk). We built the wall 5' out from the trunk of the tree, which is almost exactly where the black edging is shown in the first picture. The level of the soil in the retaining wall is a few inches higher than it is in these pictures, but the "flare" of the tree is still exposed.

 

[downunder]

Nice!

 

[kimberland30]

Uh, what part is nice? The dying grass, the ugly black edging, or the car? LOL

I'll post a picture of the "after" when I have a chance. It looks so much better.

 

[downunder]

Nice!
The design and the care to do it right. I just overlooked the lawn, I figured you knew it needed work.
Have you ever tried trenching around a bed instead of using edging? Dig out a small trench 3-4 inches wide and a couple inches deep. The lawn will give an outside "wall" and the trench will hold the mulch in the bed. It's kind of hard to do around shallow tree roots though.

 

[Scuba_Dave]

 

[kimberland30]

Nice!
The design and the care to do it right. I just overlooked the lawn, I figured you knew it needed work.
Have you ever tried trenching around a bed instead of using edging? Dig out a small trench 3-4 inches wide and a couple inches deep. The lawn will give an outside "wall" and the trench will hold the mulch in the bed. It's kind of hard to do around shallow tree roots though.

I tried the trench method before we installed the black edging, but there were problems with the roots. At least with the edging/block, we could manuever around them. I'll post a picture of the retaining wall tonight.

I'm actually doing the trench method around the rest of my flower beds because I took out all the edging, and there is no way in hell I want to spend more money on landscape block. Nor do I want to install them after the fiasco of having to deal with the tree.

Scuba Dave, that is a great picture and I may have to steal it for another board.

 

[Angarreq]

I'd love to see the after pics, I'm thinking about doing something similar to a tree in my front yard!

Thank you