Turn Autumn Tree Leaves Into Compost, Mulch, And Organic Fertilizer

Every Autumn, I see piles of tree leaves waiting for city trucks to come along and suck them up to be carried off to the municipal compost pile. If you’re a gardener, I sincerely hope that you’re saving your tree leaves for your garden. They can be used as mulch or compost and are an important source of nutrients for your garden soil and lawn.

What plant nutrients are in tree leaves?

Autumn tree leaves are one of the most efficient organic fertilizers, as they contain virtually every nutritional element your plants need. Don’t overlook them as a garden and lawn compost.

Tree leaves are the end source of all the elements a tree’s roots draw from the ground. Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, Sulfur, Copper, Zinc, Manganese, Copper, Boron, and more are found abundantly in leaves and those elements go a long way towards feeding any plant (the specific nutrients and amounts differ depending on the tree species). The yearly addition of those leaves into your garden beds, along with other forms of compost, will help create a rich, dark soil with excellent tilth.

How to use tree leaves as a fertilizer and soil conditioner

Make Compost

Shredded tree leaves are a great addition to your compost pile. But as they’re very high in carbon (a 54:1 carbon to nitrogen ratio), make sure that you’ve got enough “green” material like grass clippings, blood meal, kitchen scraps or manure (poultry or horse only) in the compost pile so the leaves break down in a timely manner. Without the added nitrogen they’ll mat together and form one big clump of dead, wet leaves. If your garden is fallow over the winter, work the shredded leaves into the soil as soon as they drop so they’ll decompose over the winter and early spring.

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Make Leaf Mold

You know that layer of black, earthy smelling soil just under the leaves and twigs on the forest floor? That’s leaf mold and it feeds plants like nobody’s business. It’s the end product of tree leaves decomposing in a moist environment, primarily by fungi.

To make leaf mold, rake your leaves into a pile and water them down. Then let them sit for two or three years. Yes, years.

That’s really all you have to do, but most of us like to contain them somehow or speed up the process. You can shred them and add them to a compost bin or a wire bin to contain them and add coffee grounds to help them decompose (coffee grounds are very high in nitrogen and possibly the perfect compliment for composting tree leaves). Turn them once in a while to make sure that anaerobic bacteria doesn’t build up and create a putrid smell.

To make a simple wire bin to compost your leaves, make a 3′ square from chicken wire, hardware cloth or similar wire fencing and place it in a shady corner of your property (you can also buy wire bins online like this one). Rake your tree leaves and load them into the bin. Leave in place for one or two years, keep the pile consistently moist and turn only once a year. Expect your leaf mold to be about 1/3rd the volume of your original leaf pile.

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Shred them

You don’t need a fancy shredder to shred tree leaves; you just need a lawnmower. A mulching blade on your mower works best, as it will grind the leaves into tiny particles, small enough to force them down to the soil line, where they’ll feed your lawn over the winter and add water-holding capacity to the soil. If you have a bag mower and a standard mower blade, use the mower to shred the leaves, which will end up in the bag. That makes for a nice, clean yard and plenty of compostable material, as you’ll have the leaves and nitrogen-heavy lawn trimmings mixed together (see above).

Work leaves into your garden beds

My personal “leaf technique” is sloppy, but it works. I simply work tree leaves into my flower and vegetable beds with a garden cultivator. If some are already dry, I crumble them up and scatter them in the bed. This gets the leaves down into the soil where the worms, fungi, and bacteria can go to work on them.

By the following spring, the leaves have decomposed and added their nutrients to the soil. It’s very important that you don’t just let the leaves lay on the surface of your garden bed. There, they’ll mat together and create a dense cover that won’t allow air and water through (but it will block weed seeds). Piles of dry leaves on your beds may simply blow away in the winter winds.

Tree leaves are a great gift for your garden – don’t let them go to waste.