Whether it will finish depends on a number of things, not the least of which are...where on the planet you are, what size the branches are, how much moisture it receives and in what ratio those ingredients are.

tj

We are in Southern Oregon, everything is shredded, the mulch is very moist right now. I'm not sure of the ratio of the leaves/grass/branches. It was from the dump.

Whether that material would be digested enough for compost depends on a lot of things starting with the Carbon to Nitrogen ratio of the materials and then the amount of moisture in the mix. Very moist may inhibit the bacterial activity just as a very dry mix would.

In a properly built compost pile smell should never be a concern so the need to cover a compost pile with wood chips to reduce any smell (odor) is not necessary.

I have had compost continue working through the winter here in Michigan when
I got the mix right.

There would be no smell from the list of materials you mention. If you have experience a smell in the past something was going wrong.

We all understand what you're talking about, but you're using the term 'mulch' incorrectly. The only time ingredients such as you describe are "mulch" is when they're actually performing as mulch, or intended for mulch, I suppose. My father had a mulch pile, and he did use it for mulch. I have a compost pile that I mostly use for mulch. Mulch is the uppermost layer of matter that you put on your gardens to discourage weeds, conserve soil moisture, etc. What you're calling mulch is what I guess I would call feedstock or compost ingredients. Given the ideal proportions, and particle size and moisture levels, etc, it's conceivable to get compost from those ingredients in four months. I'd leave off with the wood chips.

Those municipal yard waste dumps shred up everything and offer it as 'mulch' so it's not uncommon to hear it called that. In fact we call them the 'mulch sites' at our house. I agree it's only mulch when it's used as mulch.

As for the original question, kimmsr is of course right that the pile needs enough nitrogen to break down all the high carbon leaves and wood. Grass clippings are great, but it's better to mix them in rather than make thick layers. That's true for any compostable, but grass especially will mat together and be hard to turn and mix later. If you can incorporate it up front, it's better. Best would be to mulch those clippings back into the lawn, but even I have excess clippings sometimes. They're rocket fuel for the compost but mix them in if you can.

Also there are other potential nitrogen sources in winter when the grass isn't growing. Kitchen scraps are a great one - if you aren't doing that, get a small plastic pail (ice cream bucket is nice) and collect your coffee grounds/filters and banana peels and anything that once grew on a plant. Bury them in the pile to avoid critters digging around. Finally, if you're brave, pee has a lot of nitrogen and some phosphorus and potassium too. Don't laugh, a lot of people do it.

applefirewater, when you say you are getting rid of your grass, do you mean lawn?

Yes, I mean lawn.

Good for you. Not only will you kill the grass, but the soil will be richer for whatever you do in the future. I don’t mow, so I’m always “deep mulching” some part of the yard to tame it. I have an area right now that I’ve covered with dozens of Lowe’s leaf bags, some moth-eaten wool sweaters, and newspaper, then covered with seaweed and chicken house bedding. When killing lawn, there’s no end to the materials you can put under your wood chip layers.

I pretty much make compost bins/piles with exactly the ingredients you’re describing. I also add pumpkins and apples from my local dump. I have separate bins, nearer to the house, that also get kitchen scraps. If you want to contain that stuff you put on top of your raised bed, you can make a ring out of hardware cloth and pop it off when you’re ready to use the bed.

You will probably find that the center and bottom of the piles have turned into compost. Separate it and use it.

Put the rest into a new pile and let it continue to decompose.

That's so true - the outer surface of a pile may look just like it did months ago, but underneath, there's compost.