LEAVES as Fertilizer and Soil Amendment


Even though I no longer have trees on my property that produce lots of leaves, I use plenty in my garden. Yes, I do come off a bit weird dragging garbage bags around my neighborhood, but there could be worse things than being known as the “Leaf Lady”.

Why might leaves be good for the garden?

Leaves take a while to decompose. Their nutrient content is relatively low. So why are they so good for the garden? Three main reasons: Organic matter, weather protection and weed control. The key to using leaves is TIMING and PURPOSE.

Where do I find leaves?

Most any leaves will do except those from black walnut trees which release a toxin called juglone. Juglone can kill some edibles especially cabbage, eggplant, pepper, potato, tomato, apple, blackberry and blueberry. Because the roots contain more juglone than the leaves, you would never want to plant a garden near a black walnut tree.Using spring leaves as fertilizer

One more warning: Think twice about taking leaves from city streets. They tend to soak up fuel, oil and chemical residues.

Which plants may benefit from leaves?

Leaves are not a fertilizer on their own. They protect plants from sudden changes in weather and will improve soil texture once decomposed. When converted to leaf mold, leaves work great as a seed starting medium and also a soil conditioner.Mulch garlic with leaves

Examples of plants that benefit from leaf mulch:

GARLIC: Mulch with leaves directly after planting – November for most gardeners.

ONIONS: Mulch two weeks after planting and before shoots emerge.

ROOT CROPS: Mulch around carrots and beets after they emerge to keep temperatures consistent and protect from frost.

GREENS: Mulch around the plants with crushed leaves. Make sure the soil is not deficient in nitrogen before you mulch.

BRASSICAS: Cool weather crops can benefit from a fluffy blanket of leaves.

Combine leaves with…

Composted leaves can be combined with worm castings and perlite to create a seed starting medium.

Leaf Mulch Recipe

When it comes to using leaf mulch to protect the soil from weather and erosion, timing is everything.

Spring Warming

If you want your soil to warm up quickly in the spring, mulch with leaves in early fall so that they have plenty of time to decompose.Using spring leaves as fertilizer If you mulch too late, the leaves will maintain a barrier that keeps the cold in.

On the other hand if you have a problem with rodents, you might need to delay mulching until late fall after the ground has frozen but before the coldest weather sets in. This way, the critters will have already found another place to hang out over winter.

Fall Cooling

If you need the soil to cool off a bit so you can plant lettuces and cole crops such as cabbage, kale and kohlrabi, wait until the heat of the summer passes or right after a cold spell before you mulch. Mulching will keep the temperatures more consistent if a hot spell hits.

Winter Shelter

You can use leaves to protect plants during winter. However, straw, hay, or pine boughs may work better for insulating plants because they won’t compact under the weight of ice and snow. The goal is to prevent extremes of freezing and thawing. Freezing nights and warm sunny days sometimes cause heaving – plants and their roots get pushed up and above the soil surface exposing them to the elements.

Lazy Leaves

Sure, it might be easier just to lay the leaves on the ground and be done with it, but in most edible gardens, a fluffy mulch is much better than a compacted matt that grows funguses.

Chopping, shredding or crumbling is your ticket to success. Smaller pieces will allow air in while giving microorganisms more surface area to work.

I manually crumble leaves with gloved hands. If you have loads of leaves, run over them with a lawn mower or place them in a garbage can and have your way with them with a rotating edge trimmer.

Prepare First Before Applying Mulch Next to Plants

For leaves to break down, microorganisms need energy and will take nutrients from the soil to go to work on the leaves. Your soil should be in fine condition before you apply leaves. If your soil is malnourished, amend with alfalfa, fish fertilizer or other nitrogen-rich materials before mulching.

Leave at least an inch between mulch and seeds, starts or plants, to prevent diseases from humidity and lack of fresh air.

Leaves in Compost and Leaf Mold Recipes

Composting Leaves

Add nitrogen-rich materials to the compost along with dried leaves at a ratio of 60 percent browns to 40 percent greens. I’ve found when I add a bit more carbon, the greens decompose faster and smell less.

Making Leaf Mold

Leaf mold is spongy, dark and smells like nature. The value is not in the nutrients but in the organic matter. Leaf mold will help you improve the texture of your soil. Making leaf mold is easy. The hard part for some of us is finding the leaves!Making leaf mold for a garden

Pile Method of Making Leaf Mold

Simply pile up fallen leaves in a sheltered spot and leave them to decompose. Use a simple fencing system to contain the leaves. To speed up the process even more, deploy one or more of the following techniques:

  1. Keep the pile moist, especially in dryer conditions. High carbon materials like leaves will take years to decompose without water.
  2. Chop leaves with a shredder or lawn mower and cover with a tarp.
  3. Surround leaves. Line the outside of a leaf pile with cardboard to retain moisture.
  4. Contain leaves. Throw chopped leaves in a garbage bag and moisten. Close up the bag and poke several holes in it for air.

Leaves for Worms Recipe

Dried leaves get devoured by my worms, especially if I moisten them first. Added between layers, they fluff up bedding. Combine crunched up, dried leaves with vegetable slurry.

Layer leaves and slurry like lasagna or mix in a big bowl or tub first. I’ve had the best luck combining leaves with pureed melon rinds, coffee grounds, bananas and other greens.

I don’t feed my worms citrus peels, onions or cabbage scraps because they call flies, smell and I believe, frustrate my red wigglers just enough to make them go on strike.

Leaves Quick Tips

  • Leaf mold will break up dense soils.
  • Experiment with leaf mold as a substitute for peat in homemade potting mixes. Combine equal parts of leaf mold and compost. Add ½ part of perlite and ½ part vermiculite and mix well.
  • Try leaf mold to start seeds. Combined with worm castings and perlite, you’ll have a fine, airy medium that holds moisture and let’s roots spread out.
  • Oak leaves decompose slower than others due to their tannin content.
  • As mentioned above, avoid leaves form black walnut trees.



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