Landscape cloth: to use or not to use for a new rock garden

Submitted by Novak on Sat, 01/19/2013 - 10:49

I'm planning a new rock garden, and I'd like advice on whether to lay out landscape cloth at the base. My plan is to create a mound of tufa (with a sandy mix filled in between the stones) above the existing ground, which is loamy soil. Is it worth using landscape cloth to try to discourage worms? I don't think I need landscape cloth to discourage weeds -- the site was a lawn with few weeds.

Thanks for any advice.


Submitted by Hoy on Sun, 01/20/2013 - 01:42

I don't know what your climate is like, but in my climate a landscape cloth wouldn't discorage even a baby worm. The worms climb any surfaces during the night and find access to every bit of soil. Moreover you have to be very precautious not to bring worm eggs with any plant you put there.

Submitted by Novak on Sun, 01/20/2013 - 07:05

I think you're right that earthworms will be able to get into the rock garden. What I'm actually worried about is earthworms churning the underlying loam into the lean rock garden soil. So I'm wondering how well landscape cloth works to hinder the churning.

Submitted by Mark McD on Sun, 01/20/2013 - 07:55

I'm not a fan landscape cloth, although I have a gardening friend close by that uses it all the time and likes it, the primary reason cited being that it helps prevent moles/voles from her garden beds.  I bought a large roll of professional grade landscape cloth years ago, and regretted the decision for years afterwards, for a variety of reasons.  But it really comes down to what works for you, and what doesn't.  My friend also uses landscape cloth, fully exposed and anchored down, for weed management, as she used to run a nursery; it seemed an effective way of keeping large expanses free of any growth.

There was a previous discussion on this topic; I'm hesitant supplying this link as the discussion was rather contentious and a bit out of context as this particular "digression" was plucked out of a different (unrelated) topic.

Submitted by Peden on Sun, 01/20/2013 - 12:34

I have to side with the free roots gardeners here. Worms will get into your tufa bed regardless but they will stay there to grow fat only if they find it homey. Landscape cloth might aid in a battle against worms or transfer of worm soil across a desired Ph boundary. Take notes if you have this as a goal and decide to experiment as probably not much has been done in this regard. I'm working on a small area -worm free, my "New Sand Barren" (no significant Ph boundary planned here). I say working; It's got a gritty surface but otherwise might be decent worm habitat. If a worm midden shows up there, EVER, I remove it immediately. Yep; worm police! Worms find this obstruction of their liberty extremely distasteful and will leave the area. For sure: me and the worms, we have our differences!

I see a lot of "landscape" work where fabric is used on a raised or sloping area and then covered with wood chip mulch
which, of course, looks great for a week, then slides off, leaving that aura of the artificial lurking about the garden.
Wood chips being light, do not discourage little burrowing critters from using fabric as a nice stable roof either. I
don't know about stone or gravel. I have seen plantings in fabric, often used technique, which have encouraged such
activity by happy little burrowing things as to leave roots of plants pretty much exposed -the "landscapee" never notices
until said plants dry out and die.

It may be choice of fabric that wins the day. I see many cases where rammifying grasses poke right through "cheap" fabric,
excel at continuing to poke, and fabric becomes so nailed down as to become real estate. Likewise, stuff roots into
surface mulch and gardener, having gone on "vacation" for a week or year returns to find same. I prefer a good edging
program and policing of mulch to fabric against weeds for this reason.

I did use an old synthetic rug under stone chips on my driveway. The area is flat so the stones stay put, and it's worked
really quite well over the years. The only real problem has been the importation of slushy sand from the winter roads
adding sand to the stone so -it really works better if I don't drive in winter, which is not such bad idea! I screened and
redid this only once in some dozen years. As stated in one of these threads: the screening and rinsing is a hell of a lot
of work.

There are certainly good uses for fabrics (such as freeing up ground in a nursery) particularly when employed with the backing of a little thought, but I'm not sure you will gain much by using it under a rock garden of any size.

Submitted by cohan on Sun, 01/20/2013 - 16:48

If it could keep out poplar suckers I'd be inclined to try, since there is no place on my acreage unreachable by the native poplars.. oh well.. I just clip them off when they reach the surface.. there is some old weed barrier here and there in some beds my aunt and mom did years ago-- I hate it when I am digging a 'new' or overgrown old bed and run into that stuff- invisible from the surface, and fully integrated with grass etc roots...

Worm barrier is something I had never thought of! if soil mixing is the concern, maybe you just need a few inches of gravel or sand or whatever to keep the roots of the tufa plants out of the loam/border zone below..

Submitted by Palustris on Mon, 01/21/2013 - 04:00

I used it under one area as it was infested with moles coming in from the roadside verge. Generally speaking though in the other areas we have had little trouble with worms mixing the soil from below with the leaner stuff at the top. Water is going to take any excess nutriments downwards in any case and even in high mountain areas there are insects/worms which live in even the leanest soils, otherwise there would be a massive build up of undecomposed plant material.

Submitted by Novak on Mon, 01/21/2013 - 05:52

Thanks, all, for this great information! It's certainly giving me food for thought.

Am I worrying too much about worms mixing the underlying soil into a rock garden? The basis for my fretting is having heard from some rock gardeners that this is a problem over the long term... that the soil doesn't stay lean because of worm action. On the other hand, in my current rock garden (only 3 years old), I haven't noticed a lot of soil mixing from worms -- at least not yet (the garden is only three years old). I have more problems with mixing from cicada killer wasps, which are very cool insects, but they dig massive burrows.

Submitted by Peden on Mon, 01/21/2013 - 07:05

Cohan, It seems you might have a problem akin to that of Anne's "Antlered Rats" with those Poplar suckers. As to soil
mixing of any kind once soil mixes have been jiggered and let rest: In my naivety I once thought it possible. I now stand
amazed at how little it occurs. It just doesn't unless rock gardener gets in there and mixes it! Worms do move soil. It
might take a decade or two to really notice the effect (I suspect this is great cause in making sidewalks "sink" etc.) in
most places but they do move soil. If I was making an acid bed on limey soil I'd want to think over the employment of some
kind of membrane real well. Not just from attack from below, but also from attack over sides etc. as this is a case where
you might really notice worm meddling but, again, I think this is all fertile ground for experiment and observation; like;
how fast does an acid bed on limey soil become limey.... and by what mechanism if it be so? Leaching too is consideration.
I think if I put a limey (tufa) structure on acid soil (sand here) the Calcium will leach into the soil below in time
making it hospitable to plants growing in the tufa. There's also issues with tufa you won't get by throwing lime powder on
soil -but I'm getting ahead of myself!

Submitted by cohan on Mon, 01/21/2013 - 12:12

As Janet says, food for thought... I have not yet built any beds that are so unrelated to the native soil that I'm concerned- my rock gardens are made from my native soil with gravel added, so short of the worms removing the gravel there is nothing much they could do, and I'm working on a wetland sunken planting with native black soil and peat from another place on my acreage, but I don't think many of the natives I expect to plant would be concerned about any minor shifts in ph around the edges...
When/if I do some more radical soil variations I'll be thinking about it...

Submitted by Mark McD on Mon, 01/21/2013 - 16:19

I concur with Michael's comments; I had similar experience, even using high quality landscape cloth, that weed trees and other weedy plant roots can still penetrate the landscape fabric (particularly if the fabric is covered with some bark mulch) and the "fabric becomes so nailed down as to become real estate", really difficult to remove the fabric when it becomes a maintenance headache.

I must recount an experience with earthworms.  Always have earthworm activity here, in spring the night time rustling under the layer of persistent oak leaves is a bit creepy, but in the 2011 growing year, we had a freakish infestation of earth worms, never seen anything like it in my near 50 years of gardening.  I took a few photos (not the most pleasant of images), I shall spare you all, but I'm not exaggerating in the slightest when I say the earthworms were "springing out of the ground".  So loosened was the top several inches of soil (and casings) that pulling a weed, or any disturbance to the soil, a dozen earthworms or more would lurch out of the soil like porpoises jumping out of water.  Even walking on my garden paths, earthworms were jumping out of the ground. It was actually rather disturbing and nightmarish. 

When planting something, there might be hundreds of earthworms; I would scoop away the loose top layer of soil to push the earthworms away, to be able to plant something unimpeded. The earthworms got into a couple dozen peat-flats where I had Epimedium seedlings, losing a number of seedlings due to drought from so much soil churn, the soil became like loose dry pellets.

In 2012, some of my woodland beds still showed a high number of earthworms, but nothing like it was in 2011, the Year of the Worm.

Submitted by cohan on Mon, 01/21/2013 - 23:48

Never seen anything like that, Mark! But there was a period last spring when I was out late a time or two and heard that strange rustling in the leaves on the ground - loud enough that I thought it was mice- but I could never see anything (except some leaves moving) and realised it was all over the place! In daylight I could see on some beds that had a light coating of leaves, that the dried leaves had been pulled into regularly spaced little piles!

Submitted by Peden on Tue, 01/22/2013 - 08:41

LOL! The Year of the Worm! Sounds like good rich soil and a VERY WET year! Yes, I fondly remember the spring of 2011 with its great Lake Peden. I imagine most of the worms here just plain drowned. As another point about root invasion: The tip of a root leader is like one cell thick. That can get through a real small hole. When it does, if it finds nice goodies on other side of hole, the root will grow large forcing a larger hole in order to devour nice goodies; something to consider when planning barriers in soil.