I don't think sulfur would kill the grass.

I am by no means an expert on moss gardens and have only just begun one myself last year. But I think I heard you can spray roundup and it will kill plants but not moss? Please look into this before taking my advice if no one else comments.

How strange that I would come to this forum after a few years to find your message. The same thing happened to me and I posted here. I'll copy some of the relevant replies below. First, part of my backyard moss yard was transitional, in that some of it was getting too much sun and so was plagued with some weeds and grasslets that I was hand-weeding when the "tragedy" struck. The other part was doing fairly well except for squirrel activity which kept the moss scuffed up. In the end, the lawn company sprayed the yard with Roundup, which killed almost everything. Although the grass died, so did most of the moss although you could tell moss once lived there. This was in Sept. 04. It has never really recovered. On the other hand, I have not spent any time babying it back, and the part that was transitional anyway, is a worse mess than ever. I'm trying to grow vinca there now. The part that was the prettiest is finally starting to recover some, but we've had dry weather the last couple of summers.
Here are a few comments that I received from my post:

The true safe solution is to hand weed all the grass. This will be easier if the grass is young. A light rolling will smooth out the moss & give it good contact with the ground. Your Moss Garden should look as it did before the disaster. Of course your Lawn company doesn't want to hear this. I

When I ask about removing weeds from moss, I was told by a person who loves and grows moss, to use a vinegar - water solution. He says it creates an acidic soil that moss loves but most plants don't.

used a herbicide that contains the same active components as Roundup in my mossgarden, and it did a good job. Took care of all the grasses and the sagina-explosion I had going there. Took about three weeks.

So Andee, are you saying that when the lawn company sprayed Roundup, the moss died? But later you usesd an herbicide containing same ingredients as Roundup on your moss garden and it didn't kill the moss? Just wanting to clarify whether Roundup will or will not kill moss.

There was only one spraying with Round-up by the lawn company. It's hard to say if the moss died or not. It was not the pretty soft green moss I had before they slit-seeded. It looked more like the stuff you see in dried arrangements. The other problem was the slits they made in the yard which also disrupted the moss. I think that if I had babied it after that, it might have recovered more quickly. So it seems to be an in-between situation. Round-up kills grass and it won't recover; it knocks out the moss but doesn't outright kill it all beyond resuscitation, at least in my one experience.

Jeff, if you decide to use any kind of herbicide, Roundup included, test a small area before you treat any large area with it. I have (had!) a beautiful moss backyard that was badly infested with both broadleaf weeds and grasses. I had heard that Roundup wouldn't kill the moss but knew how well it worked on other weedy stuff. I sprayed my yard with it last fall and my moss still looks like the dried arrangement stuff like andee described. Since then I've read that the chemical in Roundup (glyphosate) will kill some mosses but not others. The strength you use has some bearing on the results, too.

If you use commercial products to lower the ph of the soil the grass should have a hard time growing but the moss should be fine. I haven't heard of anyone applying these over established moss but it makes the soil better for moss.

We have recently bought or better to say store sold us
Roundup transorb liquid herbicide advising that it will not kill the grass. We sprayed on almost 1 acre of yard. Grass is dead.
Any advise how to recover it.
thanks

Sulfur will lower soil pH and that is what many have recommended with other product, sulfur has the lowest environmental impact and is the most long lasting pH lowering product out there. Sulfur plus a very low concentration dose of round up could very well do the trick.

The best solution is to handweed the grass...hold the moss substrate down with your one hand and pull the grass with the other...it is a finicky and finesse type approach, but it works and will not harm the moss and your garden ecology. Try to avoid ROund up..it is not good for your environment. Good luck.

We have lots of moss and keep it tidy by plucking out the grasses and leaving it alone.

@springrain: they sold you roundup to spray on an acre of yard to NOT kill the grass? What *were* you trying to kill? That seems like a bad idea. I think you may be re-seeding next year...