How to Make Leaf Mold
Pile or bag fall leaves, keep them damp, and wait. Shredded leaves turn to leaf mold in about 6 to 12 months; whole leaves take 1 to 2 years. Bin size, mo...
Published by ThriveThyme
leaves leaf mold mulch soil fall garden
How to Make Leaf Mold
Pile or bag your fall leaves, wet them, and leave them alone. Shredded leaves become usable leaf mold in about 6 months (University of Illinois Extension) to 12 months. Whole leaves take 9 months to 2 years. No turning or added nitrogen is required.
Use the Fall Leaves Desk to check off each step this season.
What Leaf Mold Is
Leaf mold is leaves that fungi have slowly broken down into a dark, crumbly, earthy-smelling material. Penn State Extension calls it an excellent soil amendment: it is low in nutrients but improves soil structure, holds moisture, and feeds soil life. It is weed-free, unlike many manures.
It is not the tomato disease also called leaf mold. The name is the only thing they share.
How Long It Takes
| Leaves | Method | Typical time |
|---|---|---|
| Shredded | Pile, wire bin, or bag, kept damp | About 6 to 12 months |
| Whole | Pile or wire bin, kept damp | About 9 to 12 months, often longer |
| Whole | Untended pile | A couple of years |
Shredding, keeping the pile damp, covering it with a tarp, and turning it now and then all speed it up. Penn State notes a pile will still rot even if you do nothing.
Method 1: Wire Bin or Pile
- Pick a shaded, out-of-the-way spot that will not dry out fast.
- Make a ring of wire fencing or chicken wire at least 3 feet wide and 3 feet tall. Penn State suggests 3 to 6 feet across. A bigger pile holds moisture better.
- Fill it with leaves, packing them down as you go.
- Soak the pile with a hose until the leaves feel like a wrung-out sponge.
- Cover with a tarp if your fall and winter are dry or windy.
Method 2: Bags
- Fill large plastic leaf or trash bags with leaves, shredded if you can.
- Wet the leaves well, then tie the top loosely.
- Poke holes in the sides and bottom for air.
- Stack the bags out of sight. Illinois Extension notes that holes in contact with bare soil speed decay, since that is where most microbes are.
- Open a bag every month or two. Add water if the leaves are dry.
Shredded vs Whole
- Shredded leaves break down faster and fit more into a bin or bag. Run them over with a mower or put them through a leaf shredder first. See how to shred leaves for garden mulch.
- Whole leaves work too. They just take longer.
- Thick, leathery leaves such as sycamore and southern magnolia are very slow whole. Shred them or mix them into a hot compost pile. See which leaves to use or avoid.
When It Is Ready
Leaf mold is ready when most of it is dark brown and crumbly and you can no longer tell what tree the leaves came from. A few intact leaves on top are fine. Use what is done and return the rest to the pile.
How to Use Leaf Mold
- Mulch: Spread 2 to 3 inches over vegetable beds, perennial beds, and around shrubs. Keep it a few inches off stems and trunks.
- Soil amendment: Work 1 to 3 inches into beds before planting to loosen clay and help sandy soil hold water.
- Potting mix: Sift fine, older leaf mold and blend it into homemade potting or seed-starting mix.
- Compost: Save a bag of leaf mold or dry leaves as a carbon source for next summer, when green material is plentiful and browns are scarce.
Leaf mold does not replace fertilizer. Feed heavy feeders such as tomatoes and corn as usual.
Next Steps
- Set aside diseased leaves before you start. They do not belong in a cool, slow leaf mold pile.
- Build one bin or fill a few bags this month.
- Check moisture monthly.
- Start using the shredded batch next spring or fall.