Skip the fabric. Look into bulk delivery instead of bags. I prefer cedar play chips.

These are made from a tree that grows natively in my region, you probably live in a different area where your "cedar mulch" is something else (unless the bagged material is trucked in from across the country) but might still be what I would choose (if available in bulk). You haven't mentioned bark mulch, but should that end up being considered...

Here is a link that might be useful: Myth of Pretty Mulch

IF you have no plans of planting anything in the space, then I would use a landscape fabric or plastic under the mulch simply to help keep out weeds. If you think you may eventually put in some plantings, then I would not use it.

I have switched from using bark to leaf humus as a mulch. It has improved my heavy clay soil substantially. Leaf humus stays dark all season. The downside, however, is that it decomposes rapidly and needs replaced each year. In NE Ohio, you can find leaf humus for around $20 per yard. If you think you may change your mind down the road about not planting anything, you may want to consider this or some other organic material as a bottom layer of mulch to improve your soil over time. Many municipalities and counties offer organic mulch to residents through their recycling programs either for free or at cost less than you may be able to find at some commercial suppliers (though I have seen higher prices than those charged by vendors).

In response to your question, to lay mulch 3" thick, you will need around 40 cubic feet (or 1.5 cubic yards), so roughly 20 bags of mulch (if sold with 2 cubic feet per bag).

I would not recommend plastic under mulch, because a good rain will wash the mulch off, and in time the plastic will break down and you will be picking shredded plastic out of the soil for the rest of your life. Landscape fabric works and looks good for while, until the edges start to show and the weed seeds that sprout on top of it send their roots into the fabric. I wouldn't use that either. If you can't grow grass there, and you don't want to topdress with fresh mulch every year or so and pull a few weeds, then you need to put in plants that will cover the area densely enough to keep down the weeds.

In my yard, the mulched areas are the hardest to maintain. Eventually the new shrub plantings will fill them, but in the meantime it's a real PITA.

"Â Geotextiles are not effective weed control solutions for permanent landscapes
 Landscape fabrics used in permanent landscape installations will eventually become a high
maintenance issue in terms of appearance, weed control, and landscape plant health
 Organic mulches are preferred alternatives for permanent landscape installations as they can be
reapplied throughout the life of the landscape without damaging the existing plantings"

Here is a link that might be useful: The Myth of Landscape Fabric

I have to chime in on something. Just because someone has some letters after her name does not make everything said to be fact. These links have information that sound like absolute facts and one would assume with a high degree of research, but possibly from minimal research and a high degree of assumption.

I can speak about weed control in lumber yards because I did weed control in what I believe to be the closest significant lumber mill to Washington State University where that author writes from. Weed control was of the highest priority and monitored by various government agencies on that and, I assume, other mills.

The biggest reason was for fire prevention. One would have to search very hard to find a weed in the log deck. Then the logs are also stacked 36' high in an area of several acres on top of pit run rock.

The logs are constantly irrigated to prevent them from splitting near the ends reducing the amount of lumber that could be cut from them and reducing fire concerns. That would wash off most any weed seeds that blew in.

When the bark is stripped from the trees it enters a hopper where it is ground and transported directly up a belt system that spills it atop of a very large pile. Some bark is further ground and there is definite separation between various bark. It is shipped in 104 cubic yard trucks and does not generally hang around the lumber yard very long.

I think there is a great deal of myth to the assumption that bark = weeds.

I'd further defend that point by having been around bark used in planting beds from some of my earliest memories and seeing the results. To this day I can not separate the smell of bark and my early memories of my father coming home from work when I was a toddler.

It is very, very hard to find bark mulch that has not been cut with recycled and dyed wood products now. I think that makes it a little harder to tell the effectiveness of bark since it is now more of a blend.

I'm not following the bark-weed relationship. Laag-can you elaborate? When I did use it, I found bark mulch to do a good job at keeping weeds under control if applied heavy enough (a better job than, e.g., leaf humus). Are you opining that it is superior or inferior to other materials for that purpose?

I'm discrediting the link by a university horticultural blogger who is attached to some links above.

My belief is that bark mulch (not dyed wood products) is a good weed barrier (finer ground =better), aesthetically superior, and not generally a big carrier of weed seeds (especially not for the reasons given by the blogger).

Bark is also a protective insect barrier to keep wood eating bugs out. It stands to reason that it is not particularly attractive to insects. Wood is what a lot of insects eat and most critters are generally attracted to dinner when it is laid out.

I suspect that the motive is a fairly typical one of the university community. That is to promote "recycling". Dyed wood products keep old fences and pallets out of land fills (or they did when there was such a thing as land fills) and they are generally against anything that might be profitable for the evil timber industry. (is bark not recycling?)

Wood chips look like crap the day they are put down and get uglier and buggier with time.

Ever dig into a mulch pile and find it full of bugs? Ever dig into a wood chip pile that has been around for a while?

Good luck finding pure bark mulch. It is harder and harder to get because it can be mixed with dyed wood products increasing profits and most people don't care or think to see what they are really getting, so they won't pay more for pure bark. ... I will.

Weed barrier is an excellent choice. Might I suggest "Typar" or something similar. Plastic is ridiculous. Any good mulch that appelas to your taste would be fine on weed barrier. Rock, or bark are fine. Might I suggest aged Saw dust as a cheap, atractive and viable solution. If you have any lumber mills near you they may very well have huge piles of aged saw dust available for cheap. It needs to be at least 8 years old and the older the better. Wood products use nitrogen to decompose and can change your PH. Old wood products are much less nitrogen dependant and the rist of changing your PH is past. If you dont intend to grow anything in that spot or you will plant trees or shrubs in that spot there is no reason not to use weed barrier. To caluculate volume, 1 cubic yard will cover approximately 100 Sq Feet of area 3 inches deep depending on the matteial used. Good luck

"Wood chips look like crap the day they are put down...full of bugs." I respectfully disagree with Laag's final conclusions. Shredded cedar, hardwood and, yes, even shredded pallet mulches (not dyed) look really quite good in shade gardens, their decomposition does wonders for the soil and the bugs that it supports also attract insect eating birds like Brown Thrashers, Catbirds and Mockingbirds.

I get a huge charge out of watching all of the birds looking for bugs, nesting in our yard and seeing their young following them about. I haven't seen the same activity in areas of the yard mulched with bark.

It is a matter of taste, I suppose, but it seems an awful waste of potential not to do all you can to attract such delightful creatures into your garden.

Thanks for the explanation Laag. When I've referred to "bark mulch", I included all mulch that originated from trees and did not realize that there was a distinction between the wood and the bark in the mulch universe. I suspect that I am not alone. I recall someone telling me some years ago that mulch (without distinguishing between "wood" and "bark") should not be used near wood structures (e.g., porches) because it invites termites. I never did know if there was any truth to that.

Back to the use of plastic--food for thought for the OP: I have 1-foot wide area between a fence and a walkway that I can do little with because of it's size and location. Tired of killing weeds, wanting to be able to simply ignore that area, and knowing I will never plant anything in that area, about 5 or 6 years ago, I leveled the soil so that it sat slightly below the adjacent walkway and laid down 3 mil plastic (secured with landscaping pins) and covered with several inches of mulch (don't know what kind, whatever the dark mulch that is commonly sold at gas stations). I have never had a problem with run off in that area and I must say, the weed control in that spot has been tremendous. Other than getting rid of an occassional weed and replenishing the mulch now and then, the area has been maintenance free for the most part.

The problem with plastic. Plastic only lasts a few years and then it decintigrates into little flakes that work thier way to the surface and look horrible. Plastic also doesnt allow water to pass through it and creates a biological wasteland underneath it. Some people dont care if thier soil is healthy or not, ill leave that choice up to you.
Weed seeds are often viable for seven years. They lay under the plastic intill it decintigrates and then they grow. If the surface seeds are gone then little will grow untill the soil is disturbed. These are the reasons Landscape contractors dont use plastic or cheap weed barrier.
Good quality weed barrier can last longer than the weed seeds and if the area ever needs to be change the soil will be lagely weed free. If the area is left alone you will never have little pieces of decomposing plastic blowing around your yard.
I would agree that most bark looks rather ugly. Aged saw dust and the mulches that "Nippersdad" suggested look very nice IMO. Food for thought.

Why do anything? If this is an area where nothing grows, just leave it alone. If some weeds grow, cut them along with the grass.

Would wood chips sitting on the ground in an area where you don't expect to see wood chips look any better?

I would try harder at planting something. I planted Vinca right under and up to a very shady Maple. For 3 years or so, I had to weed, and water to give the plants a fighting chance to get a foot hold, but by the fourth year, they took over - no weeds, and rarely watered. If you have full sun you might try something else, but I have Vinca growing in full sun (no trees) with no problem.

I mentioned this in another post recently, but it bears repeating: If you have any trees at all in your area, you can rake up your leaves (and collect them from your neighbors) then use that to mulch thickly. It looks completely natural and when it breaks down it improves your soil for future plantings. AND it encourges the kinds of insects that you don't mind and that birds love. Unless you live in a snooty area where unraked and unbagged leaves are considered sacrilege, it's a great solution.

Good for you Julia W! Leaves make the best mulch, but make sure to chop them up with the lawnmower first, otherwise they can mat down and get sour smelling.

Or blow all over the place with the slightest breeze.

I haven't had much trouble with leaves blowing around, but I think that's because I actually "semi-compost" most leaves before I put them out -- i.e. I let them sit in a pile for a few months. They still look like leaves but they're limp enough that the wind doesn't do anything to them.

Also, most of the leaves I can collect around here are from trees that produce small to very small, sometimes finely dissected, leaves -- flowering cherry and plum, and Japanese maples (especially the laceleaf variety) -- so the leaves don't really mat up like larger leaves might, they just crumble up and break down quickly. If you have larger leaves, I would definitely do as nippersdad said and chop them up.

And if any leaves ever do move around a bit, I still (personally) consider that to be a better look than plastic mulch poking up or flat, bare expanses of bark mulch.

I'm sorry but I'm of the opinion that a mulch of whatever material chosen is not the best solution for this area. Having a broad expanse of nekkid wood chips, bark, leaves, or whatever in a sunny and very visible front garden just doesn't seem like the best plan. It would help considerably to see photos of the area and understand what else is planted in the vicinity, but there has got to be some sort of appropriate living groundcover that will work better, transition between the lawn and existing plantings and provide more visual appeal.

And I have a hard time understanding how anyone that has spent time as a professional landscaper would recommend landscape fabric as a weed barrier underneath an organic mulch product. It just doesn't work, unless maintenance is adhered to religiously. Even the landscape fabric underneath 4 inches of crushed gravel in my home nursery area allows for weed generation/penetration. btw, wood mulches do not change soil pH to any significant degree (as any organic matter decomposes, it all pretty much assumes a nearly neutral pH) and the nitrogen deprivation only occurs if the wood product is incorporated into the soil, not if used as a top dressing.

I'm with you on the landscape fabric, gardengal.