Oak leaves on a lawn. (RJ Carlson/Chicago Botanic Garden)
By Tim Johnson | For the Chicago Tribune
My village has banners up that say “leave the leaves,” and I’m wondering if this refers to leaving leaves in the garden for the winter. Will it be okay if I leave leaves in my garden beds at home? I would love to save time raking up leaves from my garden.
— Cara Coyne, Glencoe
I always look for shortcuts to maintaining my home garden, and using a mulching mower to grind up leaves on my lawn and leaving leaves in garden beds is a significant time-saver. It’s also good for the environment. I like a more natural look to my garden, which luckily is easier to maintain.
My garden has several large oak trees, so there are lots of leaves to contend with. Leaves are now falling and starting to pile up. The normal fall routine for many gardeners is to remove all the leaves from the garden and either bag them up or pile them at the curb for transportation to a landscape waste facility to turn them into compost. Personally, I’ve left leaves in my garden beds at home for over 35 years with good results; it saves lots of time for cleanup, saves fuel for blowers, and supports pollinators and wildlife. This also saves money and time, since I don’t purchase much for my garden beds. The only exception is for fall plantings, which I mulch to help the plants get through the first winter.
Fall leaves create a natural mulch, which helps suppress weeds and improves the soil with organic matter as the leaves decompose. I also don’t cut back perennials in fall; I wait until spring. The perennial foliage and fallen leaves in the beds create a natural look with lots of winter interest, and they provide a habitat for insects and wildlife. We all need to do more to support pollinators, and one way is to leave perennial foliage up for the winter and leaves in beds year-round. Just cut your perennials back late in spring to 6 to 8 inches above the ground for maximum benefit for insects. I have a large hosta planting under an oak tree that I don’t even cut back in spring — I just let the hostas grow up from the old foliage from the previous year.
Because of the mature oak trees in my garden, the leaves pile up too deeply here and there in the borders or get blown into deep piles, so I do need to take those piles down a bit to avoid smothering perennials, groundcovers, and bulbs. You can pile excess leaves in a corner to decompose and create compost to use for future soil improvement. Removing leaves from the edges of your garden beds will give you a clean boundary between the lawn and garden beds, adding some order to the garden’s appearance. You don’t need to grind leaves up to use them as mulch — just let them fall and blow into the beds naturally. The leaves I pile up in the corner of the yard break down over the course of the summer, and every couple of years I can harvest some leaf compost from under the pile.
You can use a mulching mower for the lawn to mulch the leaves and grass clippings, which saves time and returns nutrients back to the lawn. I prefer the look of some leaves left on the lawn in fall versus a clean look, so I lowered my mower cutting height to about 2 inches. My robotic mower doesn’t work well with falling leaves, which is why I use my mulching mower to grind them up. Change the direction of mowing each time you mow. You should be able to easily see the blades of grass after you’re finished mowing for the season. A thick layer of leaves that covers the grass will probably smother the lawn if you leave it through winter, and a medium to dense layer of leaves can damage any areas of lawn that were seeded earlier this fall and are just being established. You’ll need to carefully rake or blow some of the leaves off the new grass if the ground is too soft to push a mower over. If the mower leaves ruts as you go, that’s how you’ll know not to mow the area.
For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.
