Fall temperatures have arrived and leaves are falling right on cue. It is a beautiful time of year on campus and at home, but the changing of the seasons also means a change to household chores. Rakes, and eventually shovels, are waiting in the garage, but that doesn’t mean you should put away the lawn mower just yet. 

Andy Dahl, an urban forestry supervisor and campus arborist in the University of Iowa’s Office of Sustainability and the Environment, explains that there is more than one way to clear your lawn of fallen leaves.

Traditional curbside pickup is an option, but using those leaves to feed your soil and care for your gardens can improve your lawn’s health — and maybe save your back. 

Q: As a homeowner, do I need to rake my leaves?

A: No! That’s right, you can tell your spouse or partner that instead of raking, you will be watching the Hawkeyes play football and helping enrich the soil on your property. This is likely to be met with skepticism if not outright eye-rolling, so here are notes you may find useful:

• Decomposing leaf litter is a valuable addition to the soil or component of compost.
• Leaves can be used as a mulch for trees, shrubs, and flowers. This regulates soil temperature and moisture while suppressing weed growth.
• Chopping the leaves into small bits with a mower helps them break down quickly and enrich the soil, thereby fertilizing your turf.

Q: What happens to my lawn if leaves are left on the ground through the winter? 

A: Care must be taken not to leave too deep of a layer on your grass. If leaves are left on the lawn over the winter, they should be chopped up with a mower. Failure to do this can cause leaves to form large mats that can smother and kill the grass by blocking sunlight and airflow. Certain species of trees have leaves that tend to mat worse than others: Maples, oaks, ginkgoes, and large leaved species such as sycamore should be shredded if left on the landscape.

Q: If I decide to rake, mulch, or compost, when is the best time to begin that chore? 

A: The answer to that question is a personal choice. Some chase every leaf as it falls. Others wait until the last leaf has left the tree. I think that the number of trees, the type of trees, and the fall weather (whether or not it’s raining, how windy it is, how much time before the snow flies) are considerations on when to gather the leaves. If you have a forested property full of oaks or maples, you’ll want to get out several times with the mower to chop them instead of waiting for all of them to come down. It is much easier to mow 4 inches of leaves three times than 12 inches of leaves once. If you have one tree in the yard or a species like a honey locust that has very small leaves, your regular mowing should do a good job of chopping them up.

Q: If I live in the country and am without curbside pickup, is there an environmental impact to burning leaves? 

A: Yes. Burning leaves releases carbon dioxide, which can add to our carbon footprint. Many autumns are quite dry, so there is also an elevated risk of a fire getting out of control and unintentionally spreading. While the smell of smoke from burning piles of leaves can evoke nostalgia, it can also cause health risks by releasing particulates and harmful gasses, especially for those with asthma or severe allergies. Composting is a much better option.  

Q: Is my lawn mower the best option to mulch leaves? 

A: For the lawn, yes. I find a blower/vac with a bag attachment is useful for planting beds. I don’t use the bag; I leave it off and the chopped leaves mulch as I go.

Q: What are the benefits to using leaves as compost? 

A: Leaves make a wonderful compost that can improve soil structure, fertilize, and increase microbial activity of beneficial soil organisms. Care should be taken when adding leaves affected by fungal pathogens such as apple scab. Compost piles will need to attain a temperature of 140 degrees for 10 days to kill fungal spores.

At Landscape Services, we try to chop as many autumn leaves as possible from the 9,000 trees in the maintained areas of campus. When the layers get too thick on the lawn, we will then collect them with a large industrial leaf vacuum and incorporate them into our composting program. That compost is used for various projects on campus.