Leaf mold What is leaf mold?
Leaf mold is the end product of deciduous tree (or shrub) leaves broken down slowly, in cool-moist conditions, by fungi. In deciduous forests, leaf mold forms naturally as each year’s leaves fall resulting in the rich soft humus.
Although not particularly rich in nitrogen, potassium, or phosphorus, leaf mold has calcium, magnesium, and many other trace minerals. When incorporated into the soil, leaf mold physically alters the soil so that it becomes spongier, holding both moisture and air. Leaf mold also stimulates biological activity in the soil, and the fungi help plants to absorb nutrients from the soil. Most fallen leaves are slightly acidic, with a pH below 6. As the leaves break down into leaf mold, the pH rises toward neutral pH 7.
You can create leaf mold from your autumn leaves for your garden—it’s an excellent addition for gardens, raised beds, and potted plants. Over time, incorporating leaf mold in your perennial beds will improve the water-holding capacity and texture (tilth) of your soil and add more beneficial soil organisms.
How do I use it?
Leaf mold can be used on its own or in a mix by adding coco coir/peat moss, potting soil, sand, etc. I use leaf mold to supplement compost and vermicompost, coir, and sand in my potting mix. I also use it along with compost/vermicompost when transplanting into raised beds and perennial beds. I never have enough leaf mold and as I rake and collect fall leaves I do so knowing that I am harvesting a wonderful soil amendment for next year.
How do I create leaf mold?
Because nature does almost all the work, very little effort is needed beyond gathering the leaves into a pile or bag–nature does all the rest. Unlike hot composting, leaf mold is produced by a cold composting process. The decomposition is done primarily by fungi, rather than bacteria, and it is considerably slower. Leaf mold can be produced in 6-18 months.
The rate of decomposition is largely determined by several factors: surface area, moisture, and fungal action. Knowing this, you can optimize conditions to speed up the process. I’ve included some suggestions below that expedite the production of leaf mold (marked as optional).
Step 1: Collect leaves
I use leaves from my lawn, sidewalk, and driveway only, leaving the fallen leaves in perennial beds and and below trees for butterflies, moths, and other insects to overwinter on fallen leaves. While some of these leaves blow into my yard over winter, I understand that these pollinators are necessary and beneficial. It is worth a little trouble to protect them.
Step 1a: Shred leaves (optional step)
I use a vacuum shredder that sucks up leaves (that are piled up) and shreds them at the same time, but you can also do this with a lawnmower. Shredding the leaves increases their surface area which speeds up their decomposition.
Step 2: Bag or pile up leaves
I prefer to use my old plastic garbage can, and supplement that with large plastic bags (like my empty wood pellet bags). I also have a holding bin of fencing wire that will be used in the spring to restart the leaf mold after I use what I have. Pack them tightly and add some water to encourage the anaerobic fungi to break down the leaves (you want the leaves to be damp not soaking wet). If you’re using an open container, you should spray the leaves to keep them damp until winter. The amount of leaves you begin with will be reduced to about 10-20% of the original volume when finished.
Step 2a: Additives (optional)
Because the leaves are mostly carbon, you can add some nitrogen-rich material (like kitchen scraps, grass, or weeds) to feed the microorganisms. You can also add beer (I used a skunky Allagash that was lost in the fridge too long). Compost tea, vermicompost tea, manure tea, or urine can also help.
Cheers,
Mark
Leaf mold is the end product of deciduous tree (or shrub) leaves broken down slowly, in cool-moist conditions, by fungi. In deciduous forests, leaf mold forms naturally as each year’s leaves fall resulting in the rich soft humus.
Although not particularly rich in nitrogen, potassium, or phosphorus, leaf mold has calcium, magnesium, and many other trace minerals. When incorporated into the soil, leaf mold physically alters the soil so that it becomes spongier, holding both moisture and air. Leaf mold also stimulates biological activity in the soil, and the fungi help plants to absorb nutrients from the soil. Most fallen leaves are slightly acidic, with a pH below 6. As the leaves break down into leaf mold, the pH rises toward neutral pH 7.
You can create leaf mold from your autumn leaves for your garden—it’s an excellent addition for gardens, raised beds, and potted plants. Over time, incorporating leaf mold in your perennial beds will improve the water-holding capacity and texture (tilth) of your soil and add more beneficial soil organisms.
How do I use it?
Leaf mold can be used on its own or in a mix by adding coco coir/peat moss, potting soil, sand, etc. I use leaf mold to supplement compost and vermicompost, coir, and sand in my potting mix. I also use it along with compost/vermicompost when transplanting into raised beds and perennial beds. I never have enough leaf mold and as I rake and collect fall leaves I do so knowing that I am harvesting a wonderful soil amendment for next year.
How do I create leaf mold?
Because nature does almost all the work, very little effort is needed beyond gathering the leaves into a pile or bag–nature does all the rest. Unlike hot composting, leaf mold is produced by a cold composting process. The decomposition is done primarily by fungi, rather than bacteria, and it is considerably slower. Leaf mold can be produced in 6-18 months.
The rate of decomposition is largely determined by several factors: surface area, moisture, and fungal action. Knowing this, you can optimize conditions to speed up the process. I’ve included some suggestions below that expedite the production of leaf mold (marked as optional).
Step 1: Collect leaves
I use leaves from my lawn, sidewalk, and driveway only, leaving the fallen leaves in perennial beds and and below trees for butterflies, moths, and other insects to overwinter on fallen leaves. While some of these leaves blow into my yard over winter, I understand that these pollinators are necessary and beneficial. It is worth a little trouble to protect them.
Step 1a: Shred leaves (optional step)
I use a vacuum shredder that sucks up leaves (that are piled up) and shreds them at the same time, but you can also do this with a lawnmower. Shredding the leaves increases their surface area which speeds up their decomposition.
Step 2: Bag or pile up leaves
I prefer to use my old plastic garbage can, and supplement that with large plastic bags (like my empty wood pellet bags). I also have a holding bin of fencing wire that will be used in the spring to restart the leaf mold after I use what I have. Pack them tightly and add some water to encourage the anaerobic fungi to break down the leaves (you want the leaves to be damp not soaking wet). If you’re using an open container, you should spray the leaves to keep them damp until winter. The amount of leaves you begin with will be reduced to about 10-20% of the original volume when finished.
Step 2a: Additives (optional)
Because the leaves are mostly carbon, you can add some nitrogen-rich material (like kitchen scraps, grass, or weeds) to feed the microorganisms. You can also add beer (I used a skunky Allagash that was lost in the fridge too long). Compost tea, vermicompost tea, manure tea, or urine can also help.
Cheers,
Mark
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