Leaf mold – sounds bad, but it’s a good thing! By Irene Shonle, El Paso County Horticulture

 

October’s cooler days and longer nights means that deciduous trees lose their leave--and gardeners must somehow deal with them. While many homeowners rake them and put them out for pickup, I recommend you not waste this valuable resource.

Bags of leaves- what a waste to haul them off

Past blog articles have discussed some excellent ways of dealing with leaves, including mulching them into your lawn (http://csuhort.blogspot.com/2014/10/ugh-dealing-with-leaves-in-fall.html), or other composting or mulching projects (http://csuhort.blogspot.com/2018/10/uses-for-fall-leaves.html_ and http://csuhort.blogspot.com/2015/10/leaves-are-finally-falling.html).   A way to use leaves that hasn’t been addressed is making leaf mold. This sounds a bit off-putting, but it is a genius way to put leaves to good use. Leaf mold is essentially cold-composted leaves that break down due to the action of fungi rather than bacteria.

 Leaf mold is a valuable soil conditioner. It improves water holding capacity (something we all need in arid Colorado) because it can improve water retention in soils by up to 50%. It also improves the structure of the soil by lightening it and improving microbial activity. While it does add trace nutrients, it really isn’t considered to be a fertilizer – so additions of compost or other fertilizer is still a good idea, based on soil tests.

Leaf mold ready to use -Pepin County Extension

Creating leaf mold is simple. You can either create a large leaf corral (create the enclosure with wire or wood), and pile the leaves in there. You want to have a fairly big pile of leaves for best decomposition – a pile at least 3 foot wide and 3 feet tall is the minimum (or around 20-25 bags full). Thoroughly moisten the pile and let it sit, adding water and turning periodically. You can also keep the leaves in black plastic garbage bags, again adding water and poking some holes for air. This method may take up to a year, so be sure you have an out-of-the-way space for this. It can also be helpful to add a shovel full of compost to each bag.

Corralling leaves and moistening them - U Texas Plant clinic

 For fastest decomposition, shred the leaves before adding them to the pile. This can be done with your lawn mower, a shredder, a string trimmer or even jumping up and down on the dry leaves. Shredding the leaves will also reduce the space they take up, and will keep the leaves from matting together. Using freshly fallen leaves will also give decomposition a jump start. Freshly fallen leaves have a carbon-to-nitrogen ratio in the range of 30 to 1, which promotes  quick decomposition. Old leaves, including those that have been on the ground for just a few weeks, will have already lost most of their nitrogen content.

Leaf mold is ready to use when it's soft and crumbly. My favorite way to use it is as a mulch and or amendment in my vegetable garden (no weed seeds here!), about 2- 3 inches thick.  Leaf mold will not steal nitrogen from the plants around it because its already decomposed. You can also add it to new garden beds,  in containers to lighten the soil and improve water retention, or as a mulch around perennials. 

Leaf mold as vegetable garden mulch

There are so many uses for leaf mold, you might find yourself stealing your neighbor’s bagged leaves in addition to all of your leaves!