Leaves: Love 'Em and Leave 'Em!
Have you heard the slogan "Leaves: Love 'Em and Leave 'Em"? It's a Westchester County initiative to reduce yard waste.
It refers to mulching leaves in place, which is as simple as it sounds. After leaves fall off the trees, all you have to do is mulch them in place. No more back aches. Raking, blowing, and bagging leaves is a thing of the past!
Mulching in place is a great way to save time and money — and your grass and plants will thank you for it. Among other benefits, they'll grow deeper and stronger roots, which will make them healthier and more resistant to bugs and bad weather and reduce or eliminate the need for artificial fertilizers or pesticides.
In the spring and summer you see the results - a greener, healther lawn and vibrant flowers and shrubs.
Mulching leaves in place also reduces municipal costs for leaf pick-up and disposal. Plus, it minimizes waste in our landfills!
We are thrilled to announce that the Pleasantville Parks Department will be mulching leaves in place in all public parks.
Here's how it works:
The Nutrient Cycle
Every fall, when leaves fall to the ground, an important nutrient cycle starts: Nutrients in the leaves decompose over the winter and become bacteria and fungi. In the spring, when the soil temperature warms up, microbes feed on them and release valuable nutrients in plant available form back into the soil. Trees take these nutrients back up and grow new leaves.
When we remove dead leaves from our properties, we break this natural cycle.
What Tools Do I Use?
- Rotary lawn mower or mulching mower*
- Stand-up leaf shredder
- Leaf blower
*What is the difference between a regular mower and mulching mower?
Mulching mowers are the same as regular mowers except they provide the option to block the chute via a removable or openable cover, depending on the mower. The grass or leaves don't fly out the chute into a bag, but are instead chopped up multiple times through recycled airflow underneath the mower-deck and left on the ground as you continue to mow.
Professional mulching mowers come with special blades that are capable of pulverizing leaves (!), making it ideal for landscapers to use this option in the fall.
How To Mulch Leaves
Using A Lawn Mower
It's easy to do and saves time and money!
Mow your lawn when it's covered by leaves. Any type of rotary mower will do the job. Shred your leaves into dime size pieces and they will fall between the grass blades. It' also best to mow the leaves on the lawn when the leaves are dry, as this will help the shredding process. It's easy to shred thick layers of leaves, too — you can mow up to 18" of leaf clutter - just lift the front of the mower and lower it on the leaves while mowing slowly over the leaves. You may have to go over it more than once, until you see the grass through the mulched leaves. The shredded leaves will take about a week until they are completely absorbed into the lawn and start to break down.
Video tutorial on "Mulching leaves using a lawn mower".
In the fall, it's a good time to raise your mower-deck to 3" so you don't cut your grass excessively short. This way you can also mow thicker layers of leaves more efficiently as the airflow underneath the mower-deck improves.
Using A Stand-up Leaf Shredder
If you have a stand-up leaf shredder you can also mulch your leaves effectively that way. It too reduces the leaf volume from 10 to 1. Most of them have different size settings - adjust the setting to your needs. If you collect your leaves in a bag underneath the shredder it will make it easier to scatter them in different places: on top of your lawn or garden beds or use them in your compost pile.
Video tutorial on "How to shred leaves with a stand-up leaf shredder".
Using A Leaf Blower
Some leaf blower come with a vacuum kit – a vacuum and mulcher in form of a tube and a bag. You can blow the leaves in a pile and then, in the reverse setting, vacuum them up. The leaves are shredded via the built-in shredder into a bag. Leaf blowers can reduce the size of shredded leaves up to 16:1, most reduce the volume 10:1. Take the full bag and scatter the leaves over the lawn or add them to your garden beds or compost.
There are some disadvantages in using a leaf blower: It may be cumbersome to shred large amount of leaves this way as the bags are not very big and have to be emptied often. You also have to carry the bag around with you. Plus, leaf blowers are very noisy.
Mulching Leaves - (Mixed) Perennial Beds
Instead of buying mulch from the store in the fall shred your own leaves into a lightweight mulch instead - it's cheaper and insulates and protects your plants from severe winter temperatures and frost. Add leaves up to a uniform height of 2"-3" to be most effective.
The easiest way to deal with the leaves on perennial beds is to leave them until after a few days of heavy frost and your perennials have died down. Then take the mower and mulch the leaves in place on the bed. The mulch breaks down over the winter into spring and adds volume and water retention to the soil. Because you are shredding the leaves into small pieces they won't be too heavy and cause rot in the perennial crown.
Mixed Perennial Beds
If you have a perennial flowerbed with woody plants, you have two options:
- If enough space is available, carefully mulch the leaves on the bed after the first freeze and plants have died back. Be careful mowing around woody plants.
- Rake leaves carefully off the bed, then mulch the leaves on the side and return the shredded leaf litter to the bed.
Video tutorial on "How to mulch leaves - (mixed) perennial beds".
Mulching Leaves - Decorative Mulch
Most people buy mulch in mid-spring for decorative purposes and because it
- Retains about twice as much moisture
- Helps reduce weed growth
- Moderates soil temperatures by 8 to 13 degrees
Summer mulches are often left in place through the winter to reduce erosion, but they do very little to improve the soil over the winter. Decorative mulches do not break down very fast - the bigger the piece the longer it lasts.
If you want to improve your soil, you need to add finer mulch materials. You can do so by adding shredded leaves underneath your decorative mulch, pushing it aside, and then rake it back on top of the shredded leaf litter. You don't want bulky mulch pieces under the soil, where they can create air pockets next to plant roots.
Cornell University's Horticulture Department provides a quick overview of Mulches For Landscaping. Iowa State University's Extension presents a 12-page in-depth overview called Sustainable Urban Landscapes: Using Mulches in Managed Landscapes.
Benefits of Leaf Mulching
Mulching leaves in place reduces municipal costs for leaf pick-up and disposal. Plus, it minimizes waste in our landfills!
- Easier and faster than raking, "tarping," or blowing leaves to the curb
- Reduces or eliminates the need for commercial fertilizers
- Returns needed nutrients to lawn, landscape beds and/or wooded areas in a slow release organic form
- Helps soil retain moisture, reducing the need for watering in dry spells and reduces storm water run-off
- Protects landscape beds over the winter and helps cool root zones in the summer
- Lightens clay soils and gives fluff to sandy soils
- Increases biological activity of earthworms, microbes, fungi and other beneficial soil organisms that also help break down leaves
- Keeps weeds down
A Drawback of Leaving Leaves at the Curb: Phosphorus
Tree leaves are full of phosphorus. Piles of leaves can release large amounts of phosphorus into surface water run-off, ultimately resulting in high concentration in rivers, lakes, ponds and streams. It can speed up eutrophication, meaning the environment becomes enriched with nutrients, which can lead to changes in animal and plant populations and degradation of water and habitat quality (exessive algae bloom).
To learn more about the effects of Phosphorus on our water quality visit the U.S. Geological Survey's website.
Will I Have Too Many Leaves?
Probably not. Studies at the Michigan State University's Hancock Turfgrass Research Center have shown that you can mulch up to 450 pounds of leaves over an area of 1,000 sq. ft. without any ill effect on the lawn alone. In fact, tested lawns improved and greened up faster in the spring.
Also, not all leaves have to stay on the lawn.
You can also
- Apply leaf mulch 2"-3" thick to your vegetable garden and flowerbeds
- Use shreeded leaves undearneath your trees
- Leave them in wooded areas
- Keep leaf mulch as a consistent supply of carbon source for your compost in winter, spring and summer
What If I Don't Have Enough Spaces to Dispose of My Leaves?
It is better to mulch leaves in place a few times than not at all - it's still a win-win situation!
If you can't or don't want to start a leaf compost, or find someone else to take your leaves, just mulch as often as you can. This way you will still reduce the overall amount of leaves that are being picked-up
Is It True That Leaving Leaves Will Harm My Lawn?
If you are referring to whole, wet layers of leaves – yes, they "tend to mat together and form a barrier that blocks free water and oxygen movement into the soil" (Cornell University).
But shredding your leaves into fine pieces creates a very big surface area: think of a leaf as a deck of 52 cards. Once you shred a leaf it's like displaying all 52 cards next to each other. Shredded leaf litter is small enough that it will fall between the grass blades. These small pieces decompose over the winter and in spring become easily accessible to insects and microbes. These critters turn them into valuable nutrients. You will prevent excessive turf compaction, fertilize your lawn naturally and improve its soil condition.
Does Mulching Leaves Increase Nitrogen on My Lawn?
You don't have to worry about too much nitrogen. While you may increase the total carbon/nitrogen amount, leaf mulch won't affect the carbon/nitrogen ratio itself.
It's Spring and I Can Still See Some Leaf Litter on My Lawn – Is That a Problem?
Not to worry! Once temperatures warm up, your grass will start growing again and any residual leaf litter will once again fall between the blades. Any leftovers will also quickly decompose in spring in addition to being eaten by critters like leaf mites and insects, making it quickly disappear.
How Long Does It Take to See Results?
Results depend on your soil conditions, how frequently you mulch the leaves into your lawn, weather conditions, etc.
You could start to see results the following spring. For example, you may notice fewer weeds in your lawn and more worms in your garden and vegetable soil.
To completely work over nutrient depleted soil exclusively through mulching will take about 4 years.
Have There Been Any Studies Done On This Subject?
Michigan State University's Hancock Turfgrass Research Center, Perdue University and Cornell University have done studies on this topic with similar results: Leaves can be mulched without detrimental results to soil or turf.
This is a good article about the Michigan State University study on the feasibility of mulching tree leaves into existing turfgrass canopies.
A short overview of Perdue University's "Leaf Mulching Effects on Turf Performance" study.
Where Can I Get More Information?
Visit Love 'Em and Leave 'Em's website for mulching information for homeowners, landscapers, municipalities and event information.
Bedford has their own educational initiative to inform homeowners and landscapers about the many advantages of mulching leaves on site: Leave Leaves Alone.
A great article by Anna Snyder, Horticulture Resource Educator, Cornell Coroporate Extension-Westchester County: The Key To A Healthy Lawn - It's Falling From The Sky
Perdue University's Extension Horticultural website provides many links to various horticulturally related websites.