Are you transplanting veggie plants or sowing seeds? I assume that when you built the lasagna bed you included ingredients with higher nitrogen - grass clippings, coffee grounds, kitchen waste?? You should not need to add any nitrogen. You should be able to plant right into the sheet mulch materials and the roots of the plants will grow down into the soil. Anaerobes should not be a problem now that you have the material spread out with air and drainage. It will all decompose. Rachel

I am definitely not as experienced as the others but it is my understanding that ultimately, any organic material (OM) added will decompose. So theoretically, once the material you add on top is decomposed, the level will return to exactly what it was before you added anything (though this could take a few years). My advice is to dig where you need to dig relatively large holes. Put some OM at the bottom of the holes and plant. This will cause them to be a little above the dirt level. Then spread your newspaper or cardboard around (as best you can) circling the plants you have planted. Then, hopefully, you've got some good OM to start with and put that on top. Dried leaves is best for the very top, kind of looks better and also looks like regular mulch. Coffee grounds from Starbucks works as a start also but watch how much since if they are very thick, they can repel water. Though some think of this as a science, I don't. Seems like when I am building a new garden and don't plan to till, I always make some decisions "on the fly" depending on how much OM I have and how muddy (or dry and hard) the holes for planting turn out to be, etc.

you'd be surprised at how long the ingredients of your sheet compost will actually hold moisture - without a plastic cover... take the simple concept of mulch for example, plant two plants next to each other, mulch one, but not the other, water, and see which needs water first....mulching is very water efficient, and the concept is much like sheet composting...and think about it, the thicker your mulch layer the better it will hold moisture. plus it's just more organic matter to go into the soil. we kinda had a drought here in tennessee, i dunno if it was actually considered a drought, but the sheet compost i have stayed moist at the bottom, i can tell you that even though our weather may not be quite as extreme as CA's, it can get pretty hot here and only going 1 or 2 very small rains here in 2 and a half months is testing to a gardener.

The how, the why? I haven't used this method for over 20 years, but I'll take a shot at it. What I have to say is about marginal soils, not the deep silt soils of agricultural areas, nor mostly sand soils. People who have deep silt topsoil don't often come here looking for help and sand is a special situation. Most all marginal soils support plants of some kind. It's not that they won't grow anything, but they fail to grow the plants we want in a vigorous fashion. A typical marginal soil has a thin layer of topsoil over a compacted subsoil. The subsoil is often seen at a depth of 6 inches and the clay faction of the subsoil is usually 20% or greater. Compacted subsoils that contain clay suffer oxygen deficiency. Plants differ in their ability to tolerate an oxygen deficiency, and most of the plants that gardeners want can't use soil where the oxygen is depleted. Such plants have their root zone restricred to the top 6 inches. Roots that do grow deeper are inefficient and add little to the plant growth. But you don't even get a 6 inch depth for roots. The top 2 inches are subject to swings in moisture and temperture that remove this area from the active root zone. Now let's look at putting a lasagne layer over such a soil. The first thing that happens is the temperture and moisture in the top 2 inches of soil is stabilized and becomes a part of the active root zone. Where you had 4 inches, you now have 6, a 50% increase in available soil volume. It's like having a plant in too small a pot and moving it to the next size larger. Both organics and clay act as a buffer to hold plant nutrients loosely. When pure water comes in contact, these nutrients are given up and the water becomes a solution of the the things plants need. Rainfall perculating through a lasagne bed results in a weak compost tea seeping into the soil. So now we have 6 inches of root zone and a source of plant nutrients. Not great, but a big improvement over the original soil condition. Maybe this is good enough. If you choose plants that have some tolerance to oxygen deficiency and space them wide enough apart to give each plant it's needed soil volume, the result is good. An example might be hosta spaced with mulch between the clumps. It can be a neat look and is in fashion. There can also be a delayed benefit to a lasagne bed. Depending on the severity of the soil, the line of oxygen deficiency can be sudden and hard or it can be a gradient over several inches. Where the case is the latter, the increase in biomass in the active part of the soil leads to an increase of worms. Because the upper part of the oxygen deficiency zone is not completly devoid of oxygen, worms now encroach this area. As worm tunnels open airways, the upper part of the depletion zone gains oxygen and the line of oxygen deficiency is pushed ever deeper into the soil. This is one of the cases where you should not dig the soil.Where this occurs over a period of years, you may achieve a deep active root zone where plants of all types can be grown with much closer spacing. The delayed benefit is not always seen. It happens very slowly, if at all, where the clay faction of the subsoil is greater than 30%. If this is the type soil you have and you want to grow closely spaced plants of low tolerance to oxygen deficiency you will be disappointed with a lasagne bed. The best method of remediation of oxygen deficiency will differ with each soil type. Do whatever is needed and you too can have closely spaced vigorous plants ....