Fall leaves are underused. Most homeowners just rake and bag them away without a thought, but leaves are a sustainable source of superb mulch and compost. And when they sweep into fall gardens, they also create a vital protective layer that helps perennials, even tender perennials, overwinter.
So, why don't more people convert their leaves into mulch or compost? It's hard to say because it takes about the same amount of time and effort to prepare leaves for mulch as it does to bag them. Compost takes a bit more work but is well worth the effort.
Called either leaf mold or mould, the perks of leaf mulch are many. It's lightweight, breaks down quickly, doesn't bind available nitrogen like bark mulch, it's attractive, and most importantly, it's free. It also provides long-term benefits. Once broken down it improves soil organic content, and worms, soil microbes, and other soil benefactors love it.
Just a few things are needed to get leaves to the right consistency for mulch: a leaf blower/chopper, leaf piles that are suitably dry, and a place to pile the mulch over winter.
Begin by neatly raking dry leaves into stick-free piles. Prepare your leaf blower to chop leaves (the chopped leaves are usually stored in an easy-to-transport catch bag). Begin chopping the dry leaves and empty them into a designated pile spot. Leave them uncovered through winter. The leaves will break down a bit in the pile's interior making them darker and better-suited for mulch. In spring, use the mulch to dress beds as needed.
Leaf compost is rich, fertile and provides the garden with much-needed organic matter. It's easy to make too. Simply prepare the leaves as you would leaf mulch, by raking piles and chopping them up with a leaf blower/chopper. (Chopping them hastens the composting process, but is not absolutely essential.) Then contain the leaves in a composter. Be sure your composter is large enough to accommodate your leaf mass. The pile needs to be at least 4 feet high and wide to generate enough internal heat to properly compost. Refrain from packing the leaves tightly, good aeration helps the composting process. I suggest building a two or three binned composter to house compost.
Turning chopped leaves into wondrously fertile compost takes a little more effort than leaf mulch. The piles must be kept moist, turned, and sometimes treated with supplemental nitrogen. Once the leaves are in the composter, wet them through from top to bottom. Water is needed for the leaves to break down properly. Available nitrogen is needed for organic material to breakdown, and leaves are low in nitrogen, so it is helpful to sprinkle in some high nitrogen fertilizer. Organic options, like Espoma Dried Blood Nitrogen, are available. Once leaves have been wetted and nitrogen added, give the pile a mix with a pitch fork.
After only a month or so, the pile should be hot in the center and breaking down into compost. Properly decomposing piles will shrink. Be sure to turn piles intermittently as aeration helps the process. Well-tended compost takes 4 to 8 months before it's ready to use. The final product should be dark, soil-like and crumbly.
In fall, when the leaves sweep into perennial beds, I leave them until spring. The beds don't look perfectly finished under these circumstances, but the overwintering success of the plants is much higher. The leaf layer protects the plants below from cold extremes. It even seems to protect susceptible plants from crown rot. This method has been so successful, that in my Zone 7 garden I’ve been able to get frost-tender Canna, and Dahlia tubers to overwinter for the past few years.
So use your leaves. They're easily turned into the good stuff, and otherwise they'll just get dumped into the local landfill.