When I first started gardening, I wanted to mulch my garden. Coming from a commercial landscape background, it was something I was used to doing, and I understood the benefits. Then I spoke to a relative who had been gardening far longer than I, and he told me how it would burn up my plants. Being new to gardening, I took his advice. Even though I started my garden with two feet of good compost, by summertime, my soil was compacted, and the humus was gone. Without the protection from mulch, my humus layer eroded away, and the soil became infertile and compacted.
Keyhole beds. (Clover living mulch, and Shredded Hardwood)
So I decided that I would mulch my garden, contrary to many. I did not want to have any bare soil. I wanted to protect my soil like nature does.
Benefits of Mulching
1. Weed suppression – I get about 90% less weed growth in a mulched garden, then bare soil. Remember, nature will try to heal bare soil with plants. So if the soil is compacted, expect soil busting weeds with long tap roots like dandelions. Devoid of nutrients, expect nitrogen fixers and nutrient accumulators. If the soil is loose, expect weeds with a fibrous root system.
2. Water conservation – I have read that a mulched garden will require 90% less irrigation than an un-mulched garden. I cannot verify that exact figure, but I used to have cracked earth in the summer, but now when I pull the mulch back I have nice moist black soil for my plants to enjoy. Also, I rarely water once my seedlings are established.
3. Soil temperature regulation – You will definitely have warmer soil temperatures in the winter, and cooler soil temperature in the summer for most mulches. I have been warned not to mulch until summer, because the mulch can keep the soil from warming up in the early spring. I have personally not had any problems with this. I normally mulch in the early spring, or sometimes in the fall.
4. Improving soil structure – Organic mulches will decompose and add to the nutrients, and improve the organic matter in the soil. I noticed tons of earthworms after mulching, where before I wouldn't find any.
5. Mulches help to prevent splashing – This is something I noticed right away on my lettuce plants. I used to have really dirty lettuce, but after mulching the bottom leaves are much cleaner. This lack of splashing also helps to prevent disease transmission, which often takes place by spores splashing in the rain.
6. Soil compaction – This has been one of the best benefits for me. Before I mulched my soil would become compacted by summertime. Now, when I pull the mulch back, I can dig in the soil with my fingers very easily.
Nice humus layer under shredded mulch, loose soil
Problems with Mulching
1. Slugs – I have had more issues with slugs since I have been mulching. It is a drawback, but it has not outweighed the benefits. I think it is best to have a 1-2 inch layer of mulch. This helps to keep the slugs manageable, and it makes it easier to move it aside to get your small seeds going. I have had less slug issues now that I use clover as a living mulch.
2. Cost – Unless you have a free source, there is some additional cost in doing this. I think it is definitely still worth it, even if you have to buy the mulch. Although, if you can establish a good living mulch the cost is much less.
3. Labor – There is additional labor to install the mulch, but you do save labor weeding and watering, that I think at least add up to the labor to install the mulch. A living mulch like clover is less labor to install, but the weeding initially can be very time consuming.
Types of Mulch
1. Straw and Hay – You may want to avoid the hay because of the weed seeds, but there has been a lot of debate as to whether or not it really matters all that much. Straw and hay is fine for the soil as they decompose, provided the grass was not sprayed with herbicides. I don’t use straw much for mulch because it blows around my garden too much, and it is difficult to find clean straw without herbicide residue.
2. Grass clippings – Don’t use grass clippings as mulch if the lawn has been sprayed with herbicides. I like to use grass clippings as compost in place, but not my main source of mulch. I will spread my grass clippings right in my garden in a thin layer. They decompose rapidly, and add to my mulch layer and organic material. I am careful not to put the “hot” grass clippings too close to my plants.
Dried Grass Clippings
3. Leaves – Leaves are nice because most people have lots of them. The problem is that they tend to blow around. They will stay in place better, if you shred them with a lawn mower. I don’t use leaves as mulch, because I do not have many large trees close to my garden. As my trees grow though, I will use their leaves in my garden.
4. Pine needles – Pine needles look nice, but I would only use pine needles as mulch for acid loving plants such as blueberries and rhododendrons.
5. Shredded hardwood mulch – I like shredded hardwood mulch. The nice thing about it is that it has different sizes of shredded hardwood, and it decomposes into nice compost, that provides good weed suppression. The other thing I like about it is you don’t have to worry about herbicides in trees near as much as grass. I have had pretty good luck with this type of mulch.
6. Wood Chips – I like wood chips as well, but it’s messier than shredded hardwood, and the weed suppression isn’t as good, but if you have a lot of fallen branches and a wood chipper, this is a nice solution for mulch. Some people think that the wood will rob nitrogen for the soil as it decomposes, so they do not like wood chips as mulch. Wood can certainly take up nitrogen, but it will put it back in as well, so I would not worry too much about that. There are certain insects such as sow bugs and pill bugs that will show up if you put down too much wood chip mulch, but they are after decaying matter, not your plants.
7. Living Mulch – I have seen nice benefits to my living mulch or permanent groundcover. I use Dutch White Clover as living mulch in my garden. White clover is a great nitrogen fixer, and beneficial insect attractor in addition to providing the typical mulch benefits. Planting can be a bit trickier in that you need to kill or stress an area before you plant. I just put down strips of plywood in the areas I'm going to plant. I pull them up, plant my seeds, then by the time the plants are up and going, the clover has grown back in. The plants to coexist nicely, but yields are slightly less than using a hardwood mulch. For me, even with the lower yields I prefer it because it is more sustainable, not needing to bring in mulch.
Dutch White Clover Living Mulch
So consider incorporating mulch layers into your garden this upcoming growing season and enjoy the many benefits it has to offer. Also share your experiences with using mulch in the comments section below.
~ Phil Williams
Phil Williams is a permaculture consultant and designer and creator of the website foodproduction101.com. His website provides useful, timely information for the experienced or beginning gardener, landscaper, or permaculturalist. Phil's personal goals are to build soil, restore and regenerate degraded landscapes, grow and raise an abundance of healthy food of great variety, design and install resilient permaculture gardens in the most efficient manner possible, and teach others along the way.