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Annual panegyric to sheet mulch

Contributor Insanelysane commented that my tomato plants look very "robust." Let me rerun the photo:


Look at the "ground" beneath the tomato plants: That's sheet mulch. It's cheap, works for me, and it's not a lot of work. There are a lot of theories on how to do it, but this is mine; after I've explained how, I'll explain why:

Assuming the bed to have been previously mulched:

1. In the fall, I lay down leaves collected from the last fall over the beds, and material from my compost bins.

2. Over the winter, we get snow, rain, etc., which the leaves, the compost, and the existing sheet mulch soak up.

3. In the spring, I buy a couple of yards of really good compost (I use seafood compost. Do not use compost any compost that doesn't have a clear source; Municipal Solid Waste-derived compost from a landfill operator, for example). This means that the property is not self-sufficient but, though with more work I could, I do not generate enough mulch on my own. I also buy straw (generally too much, and not hay, which has seeds).

4. After the danger of frost, that is, when I can turn on the outside water, I build the sheet mulch in layers as follows:

a.) Shovel a layer of compost onto the beds, over the leaves and the last year's sheet mulch.

b.) Cover the newly composted bed with newspaper. (Some advocate cardboard, but I can get newspaper within walking distance, it covers more area for the weight, and I like the way newspaper adapts to the shape of the terrain. Some say don't use color sections in the newspaper because of the ink, but nowadays almost all colored ink is soy-based. The paper is flimsy and the sheets are smaller, so I avoid color for that reason.)

c.) Soak the newspaper with the hose to prevent it from blowing, and to add water to the mulch.

d.) Cover the newspaper with an inch or two of straw -- enough so the newspaper doesn't show through.

e.) When the time comes to plant seedlings, "punch in" a hole through the sheet mulch with a trowel and put the seedling into it. (I dump soil amendments into the hole, also.) No, I don't know how to sheet mulch for rows of seeds, like carrots or lettuce, without adding the sheet mulch after they've sprouted, which is a pain.

Other that adding the sheet mulch, I don't do anything else to the beds, like till them. In fact, I try not to walk on the soil at all. Over time, as layer and layer and layer, you will find the soil becoming softer and darker and more crumbly.

This is a very lightweight (cheap, "quick and dirty") approach. Here's a much more heavy duty approach, maybe more suitable for breaking new ground.

The advantages (which you can see) of sheet mulching are:

1. Very little weeding. The newspaper serves as a light block, so weeds don't sprout. (I do have a problem with quack grass where the plants have been punched in, because the soil is exposed, but generally weeds are easy to pull out of a sheet mulched bed when they do grow, because the soil is so soft.)

2. Very little watering. I was away for the month of July, which was very dry, and the tomato beds weren't watered at all. I came back, and they are as you see. The straw captures any rain that falls, the newspaper lets it soak through to the soil, and the newspaper also prevents evaporation.

3. Less disease. Molds and spores and TMV live in the soil, and the sheet mulch prevents them from infecting the plants through the leaves. When I didn't sheet mulch, and watered, the plants would get infected from splashed bare soil, and by this time, two or three tiers of leaves would be yellow or even blackening (depending on which mold attacked them).

4. Lazier staking. Tomatoes that touch or rest on the soil are goners. Not so with tomatoes that rest on clean dry straw (though if it rains, raise them up or pick them!)

5. Better soil. A lot of the improvement is due to the compost, the leaves, and the soil amendment. However, worms also like sheet mulch because the soil is not compacted. Worms also like darkness and moisture, which the newspaper layer provides. Further, over a season, the new mulch will settle, and open up an air gap between the soil and the newspaper. Just as in your house, the air gap insulates, and so the soil temperature doesn't fluctuate so much. So, the worms aerate the soil and also leave their lovely nutritious worm castings. (If I were more ambitious, I'd be doing vermiculture.)

So, less work, better soil, improved work -- what's not to like?

NOTE The basic theory, or metaphor, is that sheet mulch acts like a forest floor: Layer upon layer of rotting material, leading to a build-up of humus.

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NWLuna's picture
Submitted by NWLuna on

pill bugs? (aka sow bugs)

In my area these obnoxious critters love hanging out in mulch and then will eat portions out of any soft edibles within crawling range: zucchini, tomato, strawberries.

I hate sharing my garden with certain kinds of wildlife.

Submitted by hipparchia on

soy-based inks are less-toxic and more biodegradable than petroleum-based inks, but that doesn't necessarily mean that they're completely harmless.

carbon black is widely used for coloring black ink. it's not completely free of toxic materials, but some of the pigments and dyes used in making colored inks, colored paints, paints, etc are even more toxic, so avoiding the sunday comics is probably a good choice.

the world has never been completely nontoxic, even before we started polluting it on a grand scale. if you plan to lay down paper over your garden every single year for the next umpty-ump decades, you might want to eventually look for an ink-free alternative, but i don't think i'd worry about a couple of years' worth of newspaper.

after reading about your successes with it, i'm planning to try your sheet mulch method on my next garden. i'll be using cardboard instead of newspaper, simply because i have a ready supply of cardboard and no real supply of newspaper.