Slate weighs in on the great leaf debate



One of my favorite gardening writers is Slate’s Constance Casey, and darned if she
doesn’t weigh in on the topic we’re having such a lively argument about here on the Rant – leaves and what to do with them.

It’s fine to simply leave leaves on perennials. By spring,
they’ll have broken down into humus. The ideal would have been to run a
lawnmower over leaf piles and put the chopped-up leaf litter around the
plants. Lacking a working lawnmower, what I did was collect leaves in
hidden piles to break down on their own over the winter and use in the
spring or the following fall.

One caveat: Don’t use oak leaves. Part of the mighty oak’s mightiness
is that the leaves are slow to break down—they’ll make a layer like
Naugahyde. Other big leaves, like maple and tulip poplar, mat together
and in northern gardens can freeze into a giant pancake that keeps
water and air from the soil below.

I’ll tell ya, here in Maryland, that "Don’t use oak leaves" is pretty much a deal-breaker, given our oak-dominated mix of species.

Check out a couple more of my Casey faves: How not to be intimidated by Roses", and "How to plan an attractive and functional garden," with which I agree 100%.


  1. Leaving leaves on perennials in Georgia will cause many to die.

    Keep leaves off the crown. Using leaves as mulch around perennials/shrubs is great. Unfortunately wind will blow leaves back onto the crown of your plants.

    Shredding the leaves and spreading as mulch is perfect.

    I began with perennials and now have very few. Garden archetypes hold true. Now it’s shrubs, groundcovers, flowering trees, no grass.

    Twenty years ago I was too good to plant black-eyed Susan, she was too common. Slowly, a bit smarter, she shows off for me in August. My trinity in shade, hosta-helleborus-fern, remain and daylillies. Swamp sunflower are keepers. Anything easy and showy.

    The simple, sweet, pink hollyhock (biennial) are fabulous. Self-seeding every year in better places than I could imagine. With enough to give away.

    Perennials are great I started with dozens of genus. Now, taking low maintenance seriously, I’ve kept the few that take care of themselves.

  2. To me, I love fall not just for the lovely colors of the foliage, but what they give me when they hit the ground. I consider those leaves a gift to gardeners. I too have retired my powered lawn mower, except in the fall when I use it to shred all those leaves. I then rake them into my beds. This repeated practice over about five years yielded what I call “TV soil”. It was so rich I could plunge my arm into it with ease, even though it started out as hard red Georgia Clay (hi Tara). In addition, keeping leaves on your property is good stewardship too. Finally, I agree about the big leaves. I avoid those. But in a recent conversation I had with Scott Connolly,(he grew the largest pumpkin in the world for 2008), one of his secret weapons is shredded “oak leaf” mulch. Who knew? So for me, it’s no question. I’ll take those leaves, and all I can get.

  3. Here in northern Florida, the leaves don’t all fall at once–they fall in groups. We have a real winter with 6 to 10 killing frosts starting in late December. The ground doesn’t get cold, though because of the warm periods between those frosts. (That’s why tulips don’t work here unless you put them in the refrigerator.) Some of my best fall foliage photos down here were taken on New Year’s Day!

    I use all our leaves, a mixture of oak, sweet gum, maple, and pine, for mulch or compost. One of my winter tasks is to edge the turf (Yes, in reference to the previous topic, I am reducing the size of my lawn as I edge each year.) and those leaves do a fine job of keeping the turf back for a year. Here is a link to my before and after photos of my edging project and more details in my article “Cutting Edges”:

  4. In late winter I get so many live oak leaves – and I just love them. I mulch them around the camellias, azaleas, hydrangeas and gardenias – as well as around the oaks, and they’re the perfect mulch. I don’t shred the leaves first – I like that they last for awhile.

  5. I have a big honey locust tree in the front yard, and I love those little leaves for mulch — they are so small that they don’t need to be chopped or shredded, and by spring they have completely gone. And where they fall on the ground cover, they filter through to the ground all by themselves and don’t need any attention.

    Avoid using oak leaves? Hah! Like Susan, the local mix includes lots of them and they are hard to deal with for me, especially since many of them hang on the trees until January, when I am not the least bit interested in chopping, shredding or mulching.

  6. Let’s take this discussion a step further. Probably the lastest, most misunderstood gardening subject is Mycorrhizal fungus which is now available commercially. Anyone not familiar with Mycorrhizal fungus will finds lots of interesting reading by doing a search. It is a complicated subject. But, the bottom line is that this beneficial fungus develops in the COLD composting of leaf litter which drops on the ground. The feeder roots of those plants that utilize MF then feed on it just below the soil surface.

    So, shredding leaves and/or spent perennial litter and using it as mulch makes a lot of sense as MF specific to what is growing in a garden develops and encourages healthy plant growth. Mother Nature has been using this method for eons to grow her forests and grasslands.

  7. Use the oak leaves! They are higher in mineral content than any manure. Yes, they are slower to break down but if you chop them it doesn’t matter at all. Run the lawn mower over them and use them as mulch/soil amendments. They are GOLD for the garden.

  8. In areas where oak leaves are in abundance, run them through your compost or shred them. Using them as a shredded mulch is great because you are taking advantage of the fact they take a little longer to decompose. Getting the right greens/browns mix in the compost will take care of anything. My scarlet oak leaves stay on the tree through winter (zone 5b) and don’t fall until spring when (I guess?) the new leaves push them off. It is really odd.

  9. As a southern Californian, I find discussions of what to do with autumn leaves intriguingly exotic. We have deciduous trees, but they are a minority in our landscape. Basically, leaves drop all year long here– it’s just that in autumn, the mix changes a bit.

    The leaf litter kings here are the eucalyptus, which drop copious amounts of leathery leaves, bark, twigs, and gum nuts (seed capsules) all year long. The advice used to be to exclude this from the compost pile, as it contained chemicals that suppressed the growth of other plants. I can vouch for its ability to suppress seed germination, but transplants and established plants don’t seem to mind it as a mulch (as long as they aren’t buried, which is a real danger for small plants).

    nandina mentioned Mycorrhizal fungus– Our coast live oak has small, leathery and SPINY leaves which don’t seem to break down and are brutal on bare feet or knees. But recent research has revealled that these oaks have a symbiotic relationship with the fungus that grows in their leaf mulch. Gardeners long knew that native oaks did better when not underplanted and when their leaf litter was left intact. Know we know why.

  10. Living so close to so many leafy trees leaves me no option but to leave the leaves alone and let them lay where they will. Leaf litter is not a problem for me.

  11. In Oklahoma, we are covered in Oak trees, so I drag the leaves out of the bed, chop them up and put them back or on top of one of the compost piles around here. Composted leaf mulch is my best line of defense in our alkaline soil, but oak leaves “a la naturel” are a bad thing here.~~Dee

  12. A gardening neighbor and I split the cost of a shredder — we’d share it on weekends (splitting the cost made it more palatable to our non-gardening spouses. And we both had yards of less than half an acre, so it was hard to justify owning one otherwise.) He had more maples, I had more oaks, so nature even helped with the timing. The shredder took care of branches up to 3 inches thick, and had a hopper for leaves. The design was great — you could tip the thing on its side and rake into it, and direct the stream into a compost bin. We both used the shredded leaves to mulch our extensive perennial beds. Any leftovers became leaf mould by spring. Absolutely the best mulch I ever used.

  13. Like others have said—if we in Alabama didn’t use our oak leaves—what would we do with them. We have a number of water and willow oaks. Their leaves tend to make mats that water can’t penetrate—so like others we run the mower over them before raking or blowing them into the beds. The azealas really like the slightley acidic nature of oak leaf mulch.

  14. Raking leaves…now that’s a perfect example of gardening as healthy exercise! I love it. I am blessed with tons of maple leaves every year at this time so it takes me several days to accomplish the task of raking and piling them into the compost. And since I don’t have any oak trees nearby, I confess I’m considering becoming a leaf thief–picking up those bags that still show up on neighbor’s curbs where oak trees do grow.

  15. We have three pin oaks as street trees, so lots of fallen leaves this time of year. I used to run them through our chipper/shredder, but discovered a few years ago that the rotary lawnmower does just as good a job, faster, with less clogging. I mulched our sunny perennial beds Saturday with chopped leaves and piled the rest on the empty veggie beds. There will be more leaves in a couple of weeks so I’ll have to do the chore all over again, but mulching the rest of the garden. We have curbside pickup for organic matter, but I can’t see sending all that good stuff away even though I feel a little guilty burning gasoline to help the leaves decompose faster.

  16. Leaves are called leaves because they’re actually meant to be ‘left’ on the ground. All the nutrients that the shrub, tree, or perennial needs to thrive in the spring are in that leaf that it drops itself. The EXACT mixture of minerals, nitrogen, etc. plus an added microbe accumilation over the winter. SO, with that being said-I know we’ve ‘hybridized’ certain plants and trees to look more beautiful (larger leaves) in the fall and other times of the year- so we need to cancel a little of that out for the benefit of not blocking the soil below too much by just ‘thinning’ out under the oaks, etc. The BEST mulch for each tree, shrub and perennial is it’s own leaves – and maybe just a little picked up around it a and removed from the crown.
    That’s my opinion.

  17. Ditto on the above statements about the value of leaves for our gardens.

    As research for this week’s garden column encouraging readers to use leaves, I contacted Soilutions in Albuquerque NM.

    Misch Lehrer at Soilutions said that the leaf compost value comes from the poop and cadavers of the microbes that eat the leaves.

    He’s my smart brother, so I belive him.

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