Fall leaves: They're a goldmine of mulch, compost

By: Mark Bowen

The leaves have already started falling around my house, so I am eyeing spots in the landscape that need mulching. I always think it's such a shame when I see homeowners with lots of trees using store-bought bark mulches on their landscapes in early to mid-fall. What usually happens next is the leaves start falling. Then as they are raked off or blown off, the leaves are often wasted and much of the store-bought mulch ends up being raked off or blown away little by little, prompting yet another expenditure of time and money for more mulch.

There really is a better, more frugal way. If leaves are allowed to fall first before any supplemental mulching occurs, then you can spread them around so beds have an average leaf mulch layer of 3-4 inches. If you still have extra, fill up to eighty percent of a compost bin with leaves or start a new one. And if you still have extra, you can store them in perforated trash bags until more are needed in the compost or on your landscape beds.

Now I know that some people are not wild about the look of leaves in highly visible areas. If you are in this camp, you can always top off the leaves with a couple of inches of processed native mulch. This recycled mulch is practical and attractive. By topping off the leaves with mulch, the end result will be that the leaves will eventually break down and enrich your soil.

If all of your leaves fall, and you do not have enough of them to mulch all of your beds, by all means purchase some native mulch for supplemental use.

It can be a challenge to deal with leaves when they are coming down steadily or all at once. However, there are some strategies to consider when working with leaves.

Leaves are rich in nutrients. Most leaves are rich in potassium and micronutrients. These nutrients can be returned to the soil and eventually your plants if the leaves are used as a mulch in landscape bed or groundcover areas.

Leaves can save you money. Your leaves can often be left alone in beds, certain types of slightly open groundcover areas, or they can be spread around in a manner that results in a three to four inch layer of leaves being left in place as a mulch. Most shrubs and trees will benefit from a 3- to 6-inch layer of leaves as mulch. It often makes sense to keep leaves or bark mulches from piling up too thickly around the center of disease prone plants such as azaleas. A small fortune can be saved over the years by using leaves as mulch rather than disposing of them. You also might consider converting lawn areas routinely overwhelmed by leaves to groundcover areas that will be more tolerant of leaf layers.

Lawn areas. A light layer of leaves can sometimes be ground up with a mulching mower and left on the lawn. This practice can be effective as long as the leaves are ground fine enough and the quantity is modest enough to not smother the lawn. Excess debris can be relocated and added to beds or compost piles. It is important not to lower your mowing height in the hopes of making it easier to grind leaves. Lawns will handle hard freezes better if not cut too short (less than 3 1/2 inches) during winter months.

Compost extra leaves. Compost as many of your excess leaves as possible. Leaves make an excellent compost ingredient due to the carbon, potassium and micronutrients they provide. Even if composted alone, leaves will eventually decompose into a valuable dark earthy material known as leaf mold compost.

Alternatively, carbon rich brown leaves can be mixed with nitrogen rich materials such as animal manures such as turkey or chicken (not cat or dog), green grass clippings (when that time rolls around again), coffee grinds (one to two percent nitrogen content) or vegetable waste. As a general rule, mix six to eight parts of leaves with one part nitrogen rich material.

Open-air galvanized or plastic coated wire compost bins can be purchased from area plant nurseries or garden centers, or you can make your own with materials from the hardware store. Several area municipalities also sell compost bins cheaply to minimize the hauling away of leaves from the curb. Visit CE Shepherd's Web site http://www.ceshepherd.com for information on their inexpensive complete composter. This is a local company that sells them at wholesale-type prices.

Since compost piles shrink rapidly, the stored leaves will come in handy for filling in your compost bins as space becomes available during the early stages of composting. A three bin composting system works best if space permits, and it will allow you at any given time to have one pile ready to use, one pile working and one pile ready for the addition of new materials.

Join us as we build a compost bin at Westbury Community Garden and learn how to build your own. Our Hands-on Backyard Composting & Maintaining Healthy Soil is held on November 12, 3:00 – 5:30 pm. Urban Harvest Classes Calendar

Using compost. Finished compost can be added as needed to landscape beds and vegetable gardens or it can be screened and used as a topdressing over lawn areas to restore soil health. Compost contains large quantities of beneficial microbes useful in fighting off diseases and some pests. The microbes also help make nutrients available to your plants. Additionally, leaves used as mulch or compost provide a habitat for helpful macro-organisms such as earthworms and ground beetles. Ground beetles love to eat slugs and snails.

Tannic acid. It was once thought that leaves should not be left on the ground or composted due to the possibility of the tannic acid in leaves compromising plant health. The funny thing is that most of the bark mulches that were used instead are also rich in tannic acid. The reality is that in healthy soils, the humus (organic matter that has been digested by microbes) helps to buffer tannic acid and makes this issue a moot point. The exception can occur if naturally occurring beneficial microbes are routinely suppressed through the use of harsh chemical fungicides.

If your leaves are not eventually breaking down into humus by microbes, then your soil may benefit from being treated with a microbe inoculant product such as Microgro or compost tea to restart the natural decomposition process that should be occurring.

Compost tea can be made by placing finished compost in old stocking and then letting it soak in a five gallon bucket of non-chlorinated water for a couple of hours. The tea that results will be rich in microbes and micronutrients. Note to men: be sure to ask for permission before assuming your wife's stockings meet the "old" definition. I am writing from experience here, although I am far from trained.

Acidity. Another myth that has kept some people from taking advantage of leaves in the past involves the mistaken notion that acidic leaves will cause pH related problems for plants. The same natural decomposition process that helps turn leaves into humus also helps moderate pH levels. For example, finished compost will more often than not be only slightly acidic to slightly alkaline. As long as the microbes that occur naturally in your soil are not being suppressed with harsh products, they will do their job of turning the leaves into humus, a process that will keep the possible pH impact of leaves from being a problem.

Mark Bowen is Executive Director of the non-profit Urban Harvest, Inc. For more information about community gardens, classes, school gardens and farmers markets, visit www.urbanharvest.org.