Landscape Weed barrier

[Menchhofer]

Does anyone know or heard of nutrient reduction for trees when using the landscape fabric under mulch around trees? I have not seen this discussed here at any time...Just wondering........I would not think it would make any difference, but then I have been wrong before...

 

[UrbanEarth]

Coming from the point of view of someone who does more landscape maintenance than tree work (I am trying to change that though ) weed barriers do work if they are installed properly. They do not do anything if you are using an organic mulch, or shale, as the weeds will root in the mulch, as RockyJSquirrel's neighbor found out. They do however work very well if you use a hard rock (such as river rock, granite, etc) and make sure that you use a deep layer (3" works well). This helps alot as the weeds, if they start to grow, do not get much light and are usually not healthy with strong roots. This makes the occasional weed easy to pull. Weed barriesr will not keep away all weeds, but if installed correctly will do a good job.

As far as nutrient loss, I believe that there would be no difference as long as a permeable fabric was used. The old style plastic would probably cause some losses as the water is diverted away from the roots carrying any nutrients.

Alan

 

[John Paul Sanborn]

I have encontered septic conditions under the perforated plastic crap.

 

[jimmyq]

Landscape fabric using organic mulch can be aided by using a pre-emergence herbicide. I have used Casoron (dichlobenil) and Ronstar 2G with good results lasting up to one year per application.

 

[jimmyq]

I was talking more about the solution for weeds germinating in the mulch, which can be effected by use of pre-emergence products. If you are installing the bed, I would not bother with weed barrier, if you are maintaining a bed that has it installed I would either use a pre-emergent or remove the barrier entirely and remulch.

 

[M.D. Vaden]

As I had mentioned at lawnsite.com, professionals must avoid doctrines and laws.

Tree fertilizing can be good for health. And most times - in Oregon - its bad; due to longer limbs and bigger leaves. The wind and precipitation in Oregon do the greatest damage in the long haul to trees that are routinely fertilizeds.

So there is a time for root barrier, and a time to refrain.

A time for fertilizing and a time to avoid it.

There is a time for core aeration of turf, and a time to avoid it.

Its prescribed horticulture.

We have advice against the general use of landscape fabric at our site in the Advice page - www.mdvaden.com

The main benefit we discovered, if fabric is used, is the separation of gravel and similar material from the soil - where landscape or tree professionals don't want decorative rock to become embedded into the soil. Or at least embedded at a much slower pace.

Also, when rock needs to be removed for some kind of project like irrigation repair, its easier to get the gravel up when its on fabric.

We are not big fans of rock over root systems either. But the fact remains that people have a right to choose their design style and enjoy their yards the way they want.

Around Portland, weeds still grow in rock and gravel even when the fabric is placed underneath if the rock is kept moist from rainfall or irrigation - its a hydroponic situation.

So we suggest that you stay in control of decisions. What way works best. What are the conditions, what is expected to be accomplished.

 

[Toddppm]

I always, everytime without a doubt recommend not using any kind of weed barrier if using an organic mulch. It doesn't allow the mulch to breakdown into the soil which is supposed to be one of the benefits of mulching. Under rocks yes, we do it all the time, if you're using rock that hasn't been cleaned and has alot of dust in it you can expect the weeds to start growing pretty quick, otherwise you just have to keep them cleaned out like not letting 2-3 years worth of leaves and clippings lay in the rock bed. Pretty easy to clean them out and if weds do start to grow, easy to pull out or shoot em with roundup.
Just got a $600/mth maint. job at a house and part of the first thing we're going to do there is rip out the landscape fabric someone laid in about 2500 sq. ft. of beds! On top of the fabric theres actually a couple inches of dirt under the mulch which is 3 " thick in most spots, weeds growing in there no problem!

 

[John Paul Sanborn]

I've talked to a number of avid gardeners and have been told by every one of them that if you get right on the mulch in the early ppart of the spring, you will have no problems with weeds later in the year. So the barriers should not be needed.

I'm with the crowd that is against the use of rock in root zones too; heat retention and reflection can cause problems with many species. Paper birch is a good example of a tree that does poorly even on a turffed lawn with southern sun exposure.

 

[UrbanEarth]

Hey Brian, did your neighbor use a soft shale, or a gravel? I detest the shales as they turn into powder which is a perfect rooting medium. I pulled one weed out once that had about a pound of gravel attached!

I have seen weed barriers that have worked with little or no maintenance for upwards of ten years, and have seen them growing weeds like mad after one year. Go figure.

Alan

 

[M.D. Vaden]

As our website covers - for Oregon - neither the fabric, nor mulch (applied any time) will stop weeds.

Wind, birds, mower discharge, etc., all distribute seeds on top of bark and manual and chemical weeding are still needed.

As long as fabric is porous, it does not stop mulch nutrients from going down. If water can move through the fabric, so will the dilluted nutrients after continual decomposition.

But even though the good stuff can still move from mulch to soil through the fabric, its futile to use fabric under mulch, since the fabric has almost no benefit. So the nutrient issue is not a factor, since avoiding the cloth under mulch is the main issue.

Funny, I just decided to use fabric today, but only under the trampoline we bought yesterday.

Last time, the grass died from lack of light, and the barkdust put underneath was a pain for cleaning leaves. So we are going to lay a synthetic cloth only under the trampoline. That way I can use my blower, and scoot leaves from underneath.

That's my only personal use of fabric other than under our gravel paths.

 

[Toddppm]

You may be partially right about the nutrients getting through( I don't think much will) but another part I forgot to add is that the mulch never gets a chance to integrate into the soil helping the composition by being mixed in and naturally aerating the soil by the action of microbes, worms whatever.
We pulled plastic(clear) out of about 1000 sq ft of beds today, I can't remeber why the customer said he put it down, something about no weeds and a horshoe pit. This was undernreath a bunch of pines and a maple. There was about 2-3" of mulch mixed with pines needles that was breaking down nicely into to dirt with weeds growing all in it We spread the old stuff around after ripping out the plastic and put down a bunch of pine straw, first time I've used it but it looked great. At $8.50 a bag my cost it should!
Oh yeah under the plastic was a layer of fine white roots everywhere from the trees, another time I forgot the camera.

 

[Toddppm]

If there is no contact with the soil how is the mulch supposed to start breaking down and give up it's nutrients? Not many people mulch once every 2-3 years(enough time for mulch to start breaking down on it's own sitting on top of plastic or fabric)
We regularly remove excess mulch that has piled up and not started to break down.
Anyone ever read any studies of this in the Aboriculture abstracts?

 

[M.D. Vaden]

The way the mulch breaks down, is by the tiny pores enabling microbials to get into the mulch.

As long as the mulch is wet, it will break down. The fabric is not an entire seal.

For integration - most people that put down mulch for weed control don't want it to break down and integrate. They put it down for a cover. It at least reduces weeds like Yellow Sorrel that need ultra-violet light to reach the seed.

If people need good stuff in the soil, they should just lay down a layer of composted material, then lay the fabric and barkdust on top.

But again, mulch does not do complete weed control.

For anyone reading these posts - haven't you seen how the leaves in wet gutters break down and decompose?

Contact with soil is not essential for rot and decay. Tree trunks rot, like when they get topped. Those are up away from the soil.

In our yard, the slower my bark decomposes, the happier I am.