Did you read the FAQ for this forum on Interbay Mulch? It might be helpful to clarify some points and answer the questions you raise.

1) If you are not trying to smother grass or weeds, the cardboard is not necessary.

2) I'd avoid the oyster shells. They could very well deter worms along with less desirable creatures and I'd not like to take the risk. The entire point of Interbay mulching is to stimulate and develop the soil biology so that they do all the work of loosening the soil. If slugs are a problem during the growing season, use an eco-friendly slug control like Sluggo.

3) The process recommends mixing all the ingredients together. You could layer if you want, however that may not allow for as fast a result as if the stuff were mixed.

4) How fast the process works will depend a lot on the contents and the weather. The proper mix, the overall volume and warm temperatures that encourage decomposition will generally result in a finished product in 4-6 months. Attempting to do this over winter with colder winter temperatures could extend the project by several more months. Ideally, you would want to do this at the end of summer for spring planting, rather than late fall or the beginning of winter :-)

Here is a link that might be useful: FAQ - Interbay Mulch

Thank you, Gardengal48.

I did read the FAQs for Interbay Mulch.

I've also read innumerable posts with varying opinions and practices by so many gardeners using this method, lasagna, sheet layers and others that probably don't have formal names. Guess varying methods have conflated in my mind after all the reading and trying to decide which to use this fall for next spring.

I'll mix ingredients and dispense with cardboard underneath. I'll save crushed oyster shells to lighten potting mixes for salvias, lavender and echinacea. Don't have well draining soil space in enough sun to ground plant so found varieties that tolerate containers.

Think I might be well advised to double the burlap covering since the untreated product on rolls isn't nearly as tightly woven as used coffee bean sacks. I don't see what I purchased giving materials the desirable darkness indicated in the FAQs.

Can't turn the clock back so now is when I'm starting. Just pulled the last of the annuals during past 2 weeks.

After our last frost date in May when my annuals are sufficiently grown on I'll hope that 6 months was enough time to get a good start. New perennials will have to take their chances on enlarged mounds.

Thanks for your input.

I too got the impression from your original post that you were mixing lasagna beds with interbay mulching - not necessarily a bad thing. It's a "best of both" approach. Throw in a little sheet composting too and you are really cooking! ;)

Technically, the cardboard isn't required for doing interbay but I can't see that it will hurt anything to put it down first and yes, it will breakdown fairly quickly depending on moisture level maintained and the amount of materials placed on top of it - the more the better. You may encounter pieces of it still intact when planting comes but just leave it or break it up a bit and it will pose no problems.

One of the originators of IB mulching used to post here on a regular basis years ago and one point he made that stuck in my mind is that you can easily do IB in mounds rather than spread out over a large area and then, when it has cooked well, spread it out to fill the area as needed. This approach can sometimes make control and maintainence of the IB process easier - as in deeper, less burlap required, better moisture retention, etc. Just something to consider. You know you can pre-wash the burlap if you wish (recommend a laundromat) to improve its texture and tighten the weave.

Good luck and enjoy your project. ;)

Dave

Really, it's hard to go wrong. How long it will take to look like soil depends on a lot of things- moisture, composition and amount of materials, weather, etc. I've done several IB mulch beds and been very happy with the results.

As stated, you can plant into the bed even if the materials are not totally broken down. When I did that I made a little pocket of soil in the planting hole, but most folks seem to just plant. If it still looks like a pile of garbage, you can just add another layer of your favorite mulch to cover it up. As Dave said, the more materials the better.

I have used burlap to cover the bed, but I've also used bed sheets and matress pads. Any natural fiber, breathable material is OK. Don't worry about it. I'd use the cardboard, but you don't have to. Some people layer, I mix, doesn't matter. Add moisture and lots of OM. It will all be good.

Good luck and let us know how it turns out.

Karen

Dave, guess my confusion and self-doubt about all this gardening stuff is pretty obvious.

Keep wondering how I'm going to keep it moist with outside water shut off over winter but suppose it'll retain moisture much longer in cold weather if we don't get much precipitation this year. I've noticed the dirt is already staying moist and we've just our first few killing frosts.
If I can repeatedly carry watering cans up to the front bed all spring/summer I can do it from inside tap during winter. Talk about people thinking I'm crazy..."Why are you watering when there aren't any plants?" LOL

Whatever ingredients I don't fit on the beds will go into piles because I found good leaf mould in the woods this year from previous year's leaf dumps. It's free and good exercise but now I'll have piles closer and won't have to lug it from woods.

Karen, I know you have lots of experience with these methods from your posts on the Perennial and Winter Sowing forums. If you say you wouldn't do without these methods that's enough for me...LOL. You're growing healthy plants so it must be good!

Thanks for the encouragement, guys.

Told the lady in Starbucks she must think I'm crazy collecting the UCGs. She said, "Not at all. I take a trunk full of bags to my doctor for his gardens every time I have an appointment." Who knew...LOL.

Leslie

You shouldn't have to water in winter. It'll be fine. Just make sure it stays moist now, and start checking in spring when the weather gets warm. The top layers might even be frozen in winter.

Karen

1. Layering can help you get the proportions closer to optimal, but mixing everything together gets the process started sooner. There is no "right" way to pile up material for composting.
2. How much coffee grounds to add to how much shredded leaves/grass mixture is what will get that mixture composting. The only reason you would need a specific amount of either would be if you were doing a scientific study with the need to write a report. Throw your material together, but do not pack anything tightly since that reduces the amount of air available to the bacteria that will digest your material.
3. Whether you need to break up that clay soil underneath this pile first is subject to a great deal of debate. I have seen some, few, clay soils (there are many types of clay soils not just one) that need to have some OM worked in first, but most, that I have seen, do not. Most of the clay soils I have seen that do need OM worked in first have been black in color.
4. The only reason to put cardboard, or newspaper, or any other ground covering material, down is to suppress unwanted growth. If your pile of material is a foot or more thick there would be no need for anything on this unwanted growth since the pile of material would do that. Cardboard, newspaper, etc. are an aid to help extend the available mulch material and nothing else.
5. If that soil did have drainage issues you may want to consider correcting those before piling a lot of organic matter on top which may aggravate that problem before it starts to cure it. The Soil Food Web that is going to make your soil better, eventually, needs air to function and if there is insufficient air in the soil they won't.

Once I started pulling back the mulch laid in late August I found that there was some clay covering the LAST batch of mulch laid years ago. Scraped down to clay so I could try and lighten that up a bit...probably not suffiently but it made me feel like I at least made the attempt.

I worked greensand, gypsum pellets and vermiculite into about 12" of the red/tan clay. There's green marl underneath the 12-18" of red/tan clay in that bed. I was told that's hardpan and not much I can do about it on my own. I also worked in one bag of compost/finished manure (no peat) which may have been a mistake but it's done. I was attempting to get some bio activity below the fluffy "brown/green" materials but it was probably a waste and possibly counter productive.

Raising the bed seems to be my best option since I just don't have the energy/time to dig drainage trenches filled with gravel to drain water away from bed. I'm sloping it down toward the lawn so hope that helps with drainage. Sweet Alyssum seemed to like water this year so it's going in as edging toward the lawn.

Thanks for the concise comments, kimmsr. An outline helps me focus my compulsive nature.

If there were a gardening paper in my future it would be how one woman's mind was spun into utter confusion trying to do things "fast" instead of ever accepting changing soil structure is a long term process! :)

Off to pick up the day's stash of UCGs from Starbucks.

Once again gardeners are generous people with their advice and experience. Thanks, one and all.

Karen, do the bedsheets break down like the burlap does? I have some really ODD sized bedsheets that might be perfect for this. It occurs to me that old sheets at a thrift store might be cheaper than buying a bolt of burlap.

Does it matter how wide you make the humps? i.e. will separate 3ft diameter humps break down at a different rate than 1 6ft diameter hump?

I assume the burlap or sheet will need to be held down with something in the corners to keep from blowing away.

liz: My bedsheets didn't break down at all, but then I only left them in place for a short time- maybe a month or so in early spring- then I planted in that bed. I hosed them off, then hung to dry on a fence. Later, I washed in my washer and put them away. I always keep a few for frost covers when necessary, and these are the same old sheets I've used for years. You wouldn't want them on your bed, but they're fine for garden use.

It would seem that bigger humps would break down faster than smaller, but it doesn't matter much. Some folks plant into a lasagna bed immediately and this would be the same after the burlap or sheet is removed.

I hold the edge of the sheet down on each corner with a brick or very large stone. Garden staples are another option but have to go deep into the ground to work as well as a brick. You could use anything as a weight. A used mlk jug partially filled with water makes a good weight. Looks so attractive, too :O)

Karen

LOL! With the bizarre patterns on my garden sheets, nobody would notice the milk jugs. I have about 10 that I used for protecting tomatoes in the fall.

I'm hoping to set these up in the fall to spread and plant in the spring. I wonder how well the sheets would last for that time? Course, I wouldn't mind a bit if some of the colors in those LOUD 70's patterns faded!