Leaves form excellent, organic mulch for gardens

Q. I'd like to use leaves to mulch my garden. Do I need to shred them first? Are some leaves better than others as mulch? Can I let fallen leaves remain around trees to act as mulch?

A. I applaud efforts to recycle leaves into the garden. Leaves are an excellent form of organic mulch, adding nutrients and loosening soil to a rich loam. Given that it takes a few easy steps to mulch with leaves, it's surprising that more gardeners don't use this readily available resource.

Prepare the garden by clearing away diseased plants and all weeds. Leave perennial plants to die back throughout the winter unless they are diseased as beneficial insects such as Black Swallowtail Butterflies overwinter in perennial plants. Leaves should be shredded either with a leaf shredder or chopping them with the lawn mower. Thicker leaves such as those from an Oak should be run through the mower twice before using. Shredding leaves allows moisture, air and water to pass through the mulch, aiding in the decomposition process. Although it may be tempting to let fallen leaves remain under trees or on the lawn to act as mulch, this is not advisable. Leaves that are not shredded can create a thick mat, not allowing light and air to circulate around the tree and lawn, leading to disease or killing grass.

Once leaves are shredded, simply spread a 2- to 3-inch layer of leaves throughout the garden bed, leaving at least 1 inch around shrubs or plant stems to allow for air circulation. In the spring, simply work the leaf mulch into the garden bed before planting. The first time I worked leaf mulch into the garden, I was surprised at how readily it mixed into the soil, and how much easier it was to prepare the bed for planting. Adding leaf mulch to your garden each autumn will transition soil from heavy clay lacking oxygen and nutrients to a rich loose loam full of earth worms and other beneficial microbes.

Make sure leaves intended for mulch are disease free. Common ailments such as powdery mildew, anthracnose and black spot overwinter in leaves and cause problems in your garden in the spring. Also, avoid Walnut Tree leaves as they contain a naturally produced chemical that retards plant growth.

Mulching is an important end of season step in protecting your garden from erosion and prevents weeds from multiplying, and nature is lending a helping hand with leaves falling all around us.

- Olga DeSio

Q. Is fresh manure best applied now before winter? Is horse manure more beneficial than cow or chicken manure?

A. Manure has long been used as organic fertilizer in gardens. When used properly it is a great way to add organic matter to the garden, adding nutrients and loosening heavy clay soil common in the Midwest.

There's a few challenges gardeners face using fresh manure. It can be high in urea nitrogen, which can burn plants, and it can introduce weed seeds into the garden. Additionally, fresh manure can harbor E. coli and other bacteria. These challenges can be minimized by spreading up to 1 inch of fresh manure onto the garden during the autumn; these elements dissipate so it is safe for use in vegetable or flower gardens in the spring. Be vigilant in pulling weeds as they appear so they don't take hold and spread.

Fresh horse manure is readily available in our area, as many stables offer manure free to those willing to cart it from stable to their home. A ritual for my father was to visit stables each autumn, shoveling manure into every pail, bin and sturdy container he could fit into the trunk. Although appreciating the aroma is something that takes time, the payback in terms of soil quality is indisputable.

After spreading fresh manure in autumn to allow the elements to break down over winter, it can be safely worked into the soil next spring. Fresh manure can also be composted in spring/ summer so that it can be safely used later in the season.

Cow and chicken manure are also valuable sources of organic fertilizer. I purchase composed cow manure each spring as an additive to the garden. It's convenient to use in prepackaged bags purchased at garden centers, with almost no odor because of the composting process. While chicken manure has more nutrients than either cow or horse manure, it is not as readily available and can be pricey to purchase already composted, especially if your garden is sizable.

For more information on organic fertilizers, composting and general garden care, visit the University of Illinois Extension website (web.extension.illinois.edu/state/horticulture/index.php).

- Olga DeSio

• Provided by Master Gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines. Call (847) 298-3502 or email northcookmg@gmail.com.