Killing grass in the CRZ for mulching

SouthSoundTree-

TreeHouser
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I have a lot of trees that are suffering on a project from lawn in the root zone, and mower damage, particularly.

I want them to mulch over the grass and planed-off roots.

What is the best ways you've found for killing grass under existing trees.

I've used cardboard and mulch. Seems like it wouldn't suffocate the root zone as much as maybe newspaper might. Is a lack of fresh air to the roots an issue with sheet mulching?

Would landscape fabric for a few years work better?
 
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  • #4
Thanks!! I didn't know that they make biodegradable fabric.

Normally, i suggest cardboard to home owners. This is for hundreds of trees, largely in two rows of flowering cherries, down a roadway, and huge areas under big firs. Buying it, and rolling it out would be less work and no root damage or grade loss. The cherries are already topped and have mowed surface roots. No need for other impact. The firs have weak grass under them, while the cherries have lots of grass. Imagine that, no leaves, lots of sun gets to the grass.
 
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  • #5
You'd think that someone would know better, even if they are totally unaware of trees any more than a 5th grader.

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This last one had 3 big roots (~10" diameter) notched or cut through right at the root crown. They might have just dug the roots out entirely when they installed the playground on the other side of this Day Care fence.

The tree is gone.

It had P. Schweinitzii Root and Butt disease.

Oh, what are those pretty velvety mushrooms growing where we cut the roots?:O:|:
 

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Those are cool trees! Moss on trees is very foreign to me.

I think that cardboard and or newspaper works great, I would avoid landscaping fabric, it turns the soil anaerobic in my experience.
 
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  • #8
The root zones are already compacted, which will be part of the restoration. I am concerned about the air flow. I would think newspaper will make it most anaerobic.

I've transplanted moss from tree at a jobsite to a tree at home, and into a rain garden-ish garden bed. 6-8" thick from old Oregon white oaks.

Come out and check some moss some time.


Olympic National Park is around the corner, and is a tree-man's wet dream.


These aren't too bad for being 500' from my kitchen window to the west...
The small doug-firs are 50'. The right-most tall fir has lost its top at least once, with the top 15-20% being the regrown top, with a little jog to the left. IMG_20160213_090606465[1].jpg

There are 100'+ firs all day long in the local parks. Big maples, big madronas. Curved trunk, self-correcting firs leaning out over the water (slowly falling in) that you can free climb.



These two pictures show the same outbuilding, bottom right and bottom left.

These are two bald eagle perches down in the Skookum Creek valley just down the hill, 500' or so to the north.
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Beautiful place you're at Sean!

What I've heard, and believe, about newspaper is that it will keep long enough to kill the grass/weeds then eventually decompose to let air in.
 
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  • #10
Yes, I think it will do that just fine, but how anearobic does it make things in the meantime? That's my concern.

Some landscape fabric is visibly porous, some is more like cotton t-shirt weave tightness. Certainly not air tight.

I'd rather have visibly porous landscape fabric covering my head than a layer of wet newspaper. Know what I mean?
 
Yes, good point. I think the newspaper is preferred because it is a both. Anaerobic enough to kill off the grass and weeds but will decompose after. I bet it would decompose rather quickly in your climate.
 
To me it seems the newspaper would be totally worthless in wet climate. I can't imagine it would last long enough to cut down oxygen to anything, let alone kill the grass.

Normally I would use cardboard for this project, but the biodegradable landscape fabric looks very appealing


love
nick
 
I strip the crown off. Sod lifter for light scalp or scalp it with line trimmer.
Then 8 to 10" coarse mulch/ slabby stuff from tub grinding. Of course this needss to be adapted based on the existing root system and soil health and soil porosity
 
Sean, they look like ornamental cherries of some sort, they always seem to run roots along the surface, to the detriment of the mowers, they also seem to be 25 to 30 years or so, about their life span, plus one has been topped (shock horror)
A decent replacement specimen at 4 meters or so would have as much flower within a couple of years.
 
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  • #17
What do you mean, at 4 meters?


I've seen cherries in parking lot islands surrounded by asphalt here that are as big as in the picture. These are the worst trees, and oldest. The bulk, lining the roadway, are only 6-12" dbh, much younger than these pictured.

I was thinking about suggesting planting in between each tree down the roadway, too.
 
I meant specimen trees ready for planting, at 4 mtrs height, I bought some for my garden a while back, raised roots appeared after 3 or 4 years. I'll post some pics tomorrow when it gets light.
 
Boiling water or maybe a propane torch used for removing weeds from pavers might be the go. I have done the scalping before with a whiper sniper but it takes a bit of time to get it right.
 
I have used newspaper to kill grass in prep for rose gardens. It works well but you need a thickish layer 5 sheets min.
 
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