What to Use for Mulch and the fine art of Mulching 10-30-23

I often tell my students and interns the importance of mulching a garden bed. In Permaculture Design one of the tenants is never leave soil open and raw – always having something planted in it or protected as with mulch. That could include using a cover crop for winter beds, growing wide leafed plants like squash or pumpkin around the base of corn as in Three sisters to create shade, or mulch of various kinds.

We have a big chipper that turns anything organic into shreds quite fine. I save my herb stems and unwanted leaves while processing medicinal plants, and dry debris from the garden to chip up for mulch. I also run my autumn leaves thru it to create fine mulch that doesn’t layer up like paper mache in the garden beds, which prevents rain from penetrating. By making the mulch finer, the worms more easily eat it, thus creating fertilizer called worm castings as they work their way thru the soil.

I have found one of the hardest things to keep caught up on is good supplies of mulching materials so I’m always on the look-out for things to use. In the Fall I watch for piles of leaves people leave out by the curb in our town for the big elephant trunk like vacuum truck to come around and collect (I get there first). I take my light garbage can with me in the back of my van, provide Hefty construction grade black plastic bags that fit exactly over the rim, and with two leaf rakes like tongs gather leaves. I try to fill up the back of my van at least twice every fall so I have enough to last the year.

I also like straw (never hay which is clipped field grasses loaded with weed seeds) if I can find it that hasn’t been sprayed with RoundUp or Grazon (which will kill your crops). Timothy Grass is often a good substitute. I also like wood shavings from my husband’s woodworking projects on wood that hasn’t been preserved or ‘treated lumber’ (which is toxic). I like captured grass clippings from lawns not sprayed or allowed to go to seed, as this is loaded with nitrogen, the worms love it, and it breaks down into lovely loamy top soil. I have friends with a farm growing chickens that let me clean out their chicken coop for the manure and shavings. I provide the labor of replacing the shavings in exchange. I use this as a top coating, (or sometimes to make manure tea) but never dig it into the soil unless it’s been composting for at least 6 months (it’s too ‘hot’ i.e. too strong ammonia content for plant roots).

I also use wood chips in perennial beds that never get dug in. Uncomposted wood chips will suck the fertility out of good soil as it decomposes, which goes opposite to the intent of having rich fertile soil. It is OK on top but never dug in. Clunky wood chips also make nice path mulch and after about 3 years breaks down into black rich soil which can then be sifted thru ¼” hardware cloth and used directly in the soil but not until it’s completely broken down. “Back to Eden” movie talks about using wood chips in beds but they don’t emphasize the fact that the wood chips they use aren’t the rough big pieces you get from your local tree services, but are run thru a huge drum chipper that break down the pieces to fine consistency. They mention it in the movie but it gets passed by quickly so you may not make that distinction.

I often have processed herbs that don’t get used for a couple of years, which are almost powder or tea grade consistency, that I cull every couple of years. This I either use directly or mix with other mulching material for my vegetable beds. I like a finer mulch for vegs because they are closer together usually than perennial beds, especially when first planted, requiring a finer touch. Or I go mid season and replace areas where the mulch has decomposed completely leaving raw soil exposed.

When we prune bushes or hedges and run that thru the chipper that makes very nice mulch as well. I have also carefully used our office paper shredder waste to mix in other material for mulch. I’m careful not to shred shiny paper or plastic (as in windows in envelopes) in that mix because I don’t want that in my soil. Just ordinary non-shiny printed paper is OK, even colored as that is soy based ink and not particularly toxic.

Used coffee grounds make a great topical treatment as it does triple duty as a mulch. It’s high in nitrogen so is nutritious to the soil. It repels unwanted insects. Worms love it. You can mix this in with other materials as listed above. I do not mix coffee grounds in the soil as it has some unwanted effects, but as a topical treatment it’s great. It doesn’t have to be organic.

Some people like to use compost from their compost pile as a top coating as well and I have done it too if it’s not completely broken down. But usually the compost goes into the soil at the change of every season, just dug in a little, not plowed in or tilled (we are a no-till garden).

Some people even use tailings (the part of a fleece that edges the fleece unuseable) of sheep or alpaca fiber. I’ve even seen it sold in pellet form as a fertilizer. But some people just lay it down on the soil as a top layer. It eventually breaks down. If you’re going to do this though either keep it larger pieces so it can be pulled up, or cut up fine so it integrates into the soil easier. It’s a good insulator though.

I have a firm rule, nothing goes in my garden that is toxic.

And I use naturally strongly fertilizing components mixed in when I can. Yarrow, an ornamental and medicinal herb, helps the compost pile decompose quicker. Comfrey leaves being incredibly full of minerals and soil nutrients get added in the compost pile or used directly in the orchard or garden beds. Hardwood ash from the fireplace in moderation (because it is strongly alkaline and if too much can make the soil too alkaline – I recommend getting the soil tested by your local Extension Office in your county to check for pH recommendations) is loaded with needed minerals. Egg shells dried and powdered add calcium, needed for tomatoes to avoid tomato end rot which is a calcium deficiency. Epsom Salt which is magnesium sulfate a natural addition to boost soil mineralization can be diluted in water or sprinkled in soil as you plant. Used tea bags and coffee grounds in moderation can be thrown in the compost pile. Banana peels rich in potassium are another important mineral, especially for roses or the rose family of plants but all the garden can benefit from it.

I don’t use pet manure as it often contains parasites. I don’t use horse manure from animals that have been ‘wormed’ as the medicine kills the earth worms in the soil. I never use products that have been created with sludge from sewage waste as it contains loads of toxic chemicals that don’t break down. I don’t use grass clippings or straw from fields that have been sprayed with pesticides or herbicides. You have to get clever about asking for the history of the products you get from farmers because of this.

I read the labels from products that are sold as soil amendments. I will use bone meal or blood meal and rock phosphate but never commercial fertilizers like 10-10-10 as I believe it unbalances the structure of the soil. I’d rather get my nutrients in a more raw state than what is refined, Epsom salt being an exception. I will use diatomaceous earth as a pesticide as it is a natural product. Horticultural Oil or Soap is also good used to help with pests without being toxic. But you can also make garlic/pepper sprays that knock out the pests without purchasing anything. Vermiculite and perlite being soil looseners are created products but they break down in the soil. I never use commercial pesticides, herbicides (like RoundUp), or anything that ends in ‘icides’ as they are all poisons. I can find natural ways to accomplish the needs of the garden without loading the soil with the toxins that end up in the food we eat or the medicine we use.

I use mulch for two reasons other than just keeping the soil from being open raw. It holds in moisture and keeps the soil cooler in hot months. And it insulates the roots in cold weather. Since we grow year round here at Hillside Gardens in NE Georgia, we still have 4 seasons and I do cover my beds with plastic sheeting in really cold weather. But in a mild winter, just being well mulched is enough protection for my cool and cold weather crops. I just make sure I water well before it gets really cold.

I stay away from commercial mulches such as that sold for ornamental beds that are black or red. These mulches contain dye which I consider unnecessary and in some cases toxic, especially since our gardens are organic and as toxin free as I can make it.

Some people use plastic sheeting as a mulch to prevent moisture loss in summer, then pull it up and dispose of it each change of season. It may be more convenient for commercial growing but I hold off on using plastic as much as possible. “Weed Fabric” is sold in nursery stores for pathways or weed suppressants. These are usually cheap and break down ending up in the soil. The expensive commercial fabrics are different than the cheap ones in the garden stores but you pay the top price for the good stuff. Instead some people use newspaper as a top cover the same way. But unless you punch holes in the newspaper it tends to repel rainwater. Punching holes in it for the plants is also easy to keep the weeds at bay. But using newspaper is OK if you put your drip system hoses under the paper so the plants get moisture where needed. I don’t have that luxury. The good news with newspaper is it does break down and doesn’t leave plastic or toxic residues in the soil. In “Back To Eden” techniques, they put down about 12 layers of newspaper over closely mowed land (grassland or weed covered land) before layering 4 to 8” of wood chips to create their top soil. This works. Also used cardboard or corrugated paper works for this application too.

In Permaculture Design one of the best ways we have of creating or upgrading soil is something called “Sheet Mulching” also called “Lasagna Gardening” where layers of various components of garden soil are laid down sequentially. This is different from the technique in “Back To Eden” which uses only wood chips.

Every change of season we re-sheet mulch our beds to continue building the soil and increasing fertility. So every layer is really a kind of mulch. Things we use for this purpose include: grass clippings, autumn leaves, kitchen waste (not as a top layer), worm castings (purchased commercially or created in one’s own vermaculture device), vermiculite or perlite for drainage, sulphur (if the soil is too alkaline) or baking soda if too acid, sand or crushed granite (usually mixed 50:50 with hardwood ash from the fireplace – sifted), Bio-Char – charcoal infused with fermented soil microorganisms, top soil, composted animal or ‘humanure’ (carefully processed to eliminate disease causing bacteria – see the book “Humanure”), compost from your own compost pile or purchased, alfalfa pellets (organic, not GMO), straw, newspaper office paper shredded, often mixed in with other components as above so it doesn’t layer, chipped organic matter from tree or bush prunings, rotten fruit from orchards, or other organic matter.  

Instead of purchasing already created garden soil or potting soil from a nursery supply, or at the big box stores in bags, for years we have used this technique of mulching or advanced mulching “sheet mulching, to create and upgrade our soil every season. As a result our soil is incredible loamy rich fertile soil that grows anything. When creating the soil originally we always use about 20% of the native clay here in Georgia (very high in minerals), and draw from the environment the other components, only resorting to purchased material like worm castings (to fill in our own vermaculture activity), or sand or crushed granite (Quikrete All Purpose sand usually found in the construction part of the store) because they don’t come from our area. Otherwise most of the other stuff can be found locally or generated here as part of our processes. We just don’t waste organic material unless it has become contaminated somehow. We keep a container on the kitchen counter for almost all of our kitchen waste including egg shells which we crush in the blender, coffee grounds, and vegetable parings. That usually gets dug into the beds or put on the compost piles.

Creating and upgrading the soil is a major part of the success of any garden activity, whether used for growing food and herbs, or ornamentals. Being wise with the materials at hand, and keeping the soil covered and amended will give you the most luxuriously beautiful fluffy, fertile soil imaginable. Now if you can only keep the deer out of eating your beautiful organic produce! Or keeping the voles and tunnel making critters out.

Diann Dirks 10-30-23