I use grass clippings all the time for mulch, use it 3-4 inches deep or a little less. I have never had it slimy or thatched at that level of mulching. It decomposes quickly for me actually, I put on my veggie garden this year, I will do so again mid summer. My precious compost even if not fully decomposed is for my roses! Also remember not to put it right next to your roses. I leave a small area 1 to 2 inches or so around the roses. This way the rain can get in and that really the only area I will have to weed. Ive even used grass clippings in shady areas, it has never turned slimy on me.

Silverkelt

I have used it for years and love it. If you put it on really deep (more than 4 or 5 inches) it does tend to mat down. I have used deep piles to smother weeds in areas but have never had it turn slimy nor smother anything I didn't want to smother. Like Silverkelt, mine decomposes really fast and I replenish my beds several times a year.

Thanks so much for putting my mind at ease about the grass clippings, but now it has raised another question. I saved about 3 large yard bags (brown, compostable)and left them in the garage over the weekend. Now there is a strong ammonia smell in the garage which I KNOW is coming from the grass. Any ideas for 'saving' it? It's too much for my composter which is already green-heavy. I do have a small free area in the rear of my property near the fence. Would it be OK to dump it there?
Sorry to be such a pest, but I really don't know what I'm doing when it comes to composting and mulch and such.

Yep, that would be a good thing to do, so you do know what you're doing. :O)

Even though they are brown in colour, they are still a 'green' which is indicated by the amonia smell. If you can find a scource of brown to mix it with that would be great, or even just mix some soil into the grass clippings. Fluff it up a bit to get some air in there too.

Good stuff!

Thanks Tiffy - to the rescue again and none too soon. That ammonia smell is knocking me over so I'll be glad to put the cuttings in the back. BTW, you should see my Hosta babies which I overwintered by plunging in the ground and covering with leaves!! They are now showing their 'true colours' and will be in the ground in the next few weeks!! I had no luck WSing Astilbe, so I'm trying summer sowing them - it woud be nice to have some next year. Happy Gardening!!
Northerner.

That strong smell of ammonia you were talking about. Is it harmful? Can it catch fire on its own? I have two bags of lawn clippings in the paper disposal bags in my garage. I live in Texas and it can get up to over 110 degrees Fahrenheit in there during the day. The smell is getting stronger and trash day is 4 more days away. I tried to move the bags out to the front but the HOA might call me and make me move them. Oh, and as I moved them I saw a white foamy substance on the bottoms of the bags. How dangerous is the nitrogen/ammonia coming from the bags and what harm can it cause? Poisonous? Fire hazard? Other?

Please let me know ASAP

I get a hot steamy mess in my gardens if I pile just cut fresh grass thicker than 2"! I like to dump clippings out and kind of spread it out for a few days before I use it as mulch. As a note, NO MULCH should be laid up against the base of any plants; keep a little circle around the stem :D

Vera

Jaesun, please check your inbox. I did not realize your question was posted here until after I replied to your e-mail address.
Northerner.