Safe mulch shred leaves on new young grass lawn?

Discussion in 'Turf Renovation' started by roody2333, Dec 6, 2018.

  1. roody2333

    roody2333 LawnSite Bronze Member
    from nj
    Messages: 1,019

    my theory has always been not to mulch leaves into a newly seeded lawn (grown about 8 weeks before leaves fall and are mulched), because as the leaf mulch decomposes back into soil (compost technically), I'm concerned that the new grass roots and crowns are so small that it might get taken out in the process of the leaves composting back into soil.

    As many of you know, you can mulch like a 3 foot pile of leaves over a mature established lawn and it won't hurt the lawn, come next spring you'll see none has been killed. Mature grass has a hardier root and crown.

    But I really do not like removing leaves, so I'm trying to figure out if it's true or not that mulching over a new lawn will kill it.

    This plot is as best I have for example this year as a newly seeded area even though it was about %65 mature grass seeded a couple years ago, but the other %35 was patches/crabgrass and seeded around Sept 14th this year. All Turf Type Tall Fescue. Then the leaves fell and about 8 weeks later were mulched.
    I should be able to tell if in Spring I see any patches of no grass even though I don't have a test plot of %100 new grass grown this September.

    pic of grass blades is how it looks before leaves were dumped on it (it's about %35 new grass).
    As I mulched the leaves, I blew them closer and closer into a more dense pile.
    And then there are two pics showing the grass after all leaves were mulched, and 1 pic of a close up of the leaf mulch in the grass blades.

    Will see what happens in Spring, and I'll give it some spring to bounce back instead of assuming as soon as the weather cracks that there should be grass because the crown may very well still be alive and I will give it a chance to see if it sends new blades up.

    mulch shred leaves on new young grass lawn (1).JPG

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    mulch shred leaves on new young grass lawn (7).JPG

    mulch shred leaves on new young grass lawn (4).JPG

    mulch shred leaves on new young grass lawn (5).JPG

    mulch shred leaves on new young grass lawn (2).JPG
    KerbDMK likes this.
  2. OP

    roody2333 LawnSite Bronze Member
    from nj
    Messages: 1,019

    BTW "will unmulched leaves kill lawn" , I'll make a separate thread.
    A lot of people wonder if you just leave leaves on the lawn all Winter, will it kill the lawn.
    Some think it's beneficial and insulates the crowns although cold doesn't really hurt Tall Fesue/Rye/Kentucky blue in this zone.
    Not talking about newly seeded lawn, just mature established lawn which goes dormant for winter.

    Of course it's not preferred to leave leaves but still running the test. Sometimes there are late-falling leaves, or leaves that blow in and then it snows and stays snow covered for weeks/months and then just decide to deal with them in Spring.

    I'm Putting bricks over mature grass all winter, and netting-down piles of leaves in spots all winter and will see if it bounces back or not.
    KerbDMK likes this.
  3. LawnSite Fanatic
    Messages: 5,688

    If you get the leafs up first thing in the spring doesn't hurt a thing.
    rlitman likes this.

    JLSLLC LawnSite Fanatic
    Messages: 13,867

    It doesn’t look bad from the pics.. I was doing clean ups this week until the snow came, and the leaves here are starting to white mold on the bottom..

    Where did the makita come from?
    Walker56 likes this.
  5. Valk

    Valk LawnSite Gold Member
    Messages: 3,212

    Biggest issue is whether new grass has an 'established enough' root system to withstand all the heaving of the soil due to the numerous freezings/thawings over the course of a typical Winter.
    If new grass planted too late in Fall, well, there's the 'root of the problem'. Get it? lol

    Oct 15th is the magic date around here for a late Fall seeding...and I'll estimate that w/ our weather pattern THIS year, that late-Sept/early-Oct would have been a better target date due to our coldest Nov/2nd snowiest Nov on record..
  6. KerbDMK

    KerbDMK LawnSite Bronze Member
    Messages: 1,423

    Fun idea roody, it will be interesting to see what happens. I’ve read many times that un-mulched leaves can encourage more snow mold, and so will excess nitrogen, so snow mold will be something to look out for next spring.

    Oak and other nut trees’ leaves don’t play well with grasses, but those look more like maple leaves of some kind.

    It’s also fun to see the wide variety of blade widths in your tttf lawn.
  7. Greencuts518

    Greencuts518 LawnSite Fanatic
    Messages: 7,495

    As long as they don't leave piles, we had piles under the snow for 3 weeks and it was starting to suffocate it. Luckily it melted a week ago and we got all the piles bagged up. Next year I'm buying mulching blades and see if I can mulch the majority of the leaves throughout 6 weeks of leaf season. Almost 100 bags off a 1/4 acre. That seems like an awful lot to make disappear in a small area.
  8. LawnSite Fanatic
    Messages: 5,688

    Yes piles wouldn't be ideal.

    Although, I cover my septic tank and line with leafs every fall. Been doing it since 1991. 2 ft thick and come spring I blow them off and within 1 week it greens-ups like the rest of my yard.
    Almost 30 years and no problems.
    My dad has been doing it for 60 years.
    Pretty much everone here either covers septics with straw, hay, or leafs. I've never seen it kill grass.
    Greencuts518 likes this.
  9. RigglePLC

    RigglePLC LawnSite Fanatic
    Messages: 15,622

    My neighbor does not rake his vacant lot, and he stops mowing about October first. I don't know how there is any grass that survives every spring. There was a thick mat of leaves just before it snowed. Mostly cottonwood and black locust. If the snow melts I will get a picture--and again in spring.

    Not sure if it is possible to do an indoor experiment. I could smother some new seeded grass in an inch of ground leaves--comparing survival with a half-inch of leaves.

    Possibly, I could seed some grass in soil and cover with chopped leaves for mulch (indoors in pots.)
    Would this work?
    Last edited: Dec 7, 2018
  10. OP

    roody2333 LawnSite Bronze Member
    from nj
    Messages: 1,019

    I was thinking of doing an indoor grow and putting it outside in the cold and elements and smothering with mulched leaves so the test can be done on %100 newly-grown grass, but the grass in photos was already started around mid September like it should be, so about 3 months head start on the root system vs if start seeds indoors now.
    Not to mention some leaves have been sitting on the lawn for about 6 weeks already and decomposing in moisture. I just mulched them a few days ago. Some spots already look like they are dead (but aren't) for example the bottom left of the pictures with the wood board, you can see patches which are where leaves have been sitting for about 6 weeks and soggy but it was green grass before the leaves sat there, then I blew the leaves around to mulch them a few days ago so I un-did some of the affect those leaves had on that particular area of grass which is what I'm testing to begin with. BUT I still have some areas that are like that and will mark them with flags and not blow out the leaves, instead I will pile more leaves on them and net it down too. I blew the leaves out where that wood board is just to show that there IS grass under where I then piled leaves. I left a wood board on the lawn also just for good measure.
    I'm getting ahead of myself now - the netted-down leaves was barely seeded this Fall, it's mostly mature established grass and maybe %7 of it might be new grass (I just threw some seeds, not much and didn't water it so IDK how much grew), unlike the first pics I posted are about %35 new grass started in September. Was going to make a separate thread about leaves mulched and leaves unmulched left on mature grass besides this thread about leaves mulched over new grass, but will just post both in this thread.

    If I do the whole experiment inside in order to do the test on %100 newly planted grass, it'll be too warm and grass won't go dormant. It'll be like how in Spring/Summer you leave a board or something anything on the lawn too long and it goes yellow and white then dies if covered for a few weeks. When it's dormant is a different story though it's basically shut down.

    so yea I didn't do this test to a T but I can next Fall. I really should have killed a spot with roundup, then done the tests on %100 newly planted grass, both with mulching leaves and with unmulched leaves and separate spots with LOTS of mulched and unmulched, and then spots with not as much leaves mulched and unmulched.
    And the mature lawn test I should not have seeded at all even if it was just minimal seeds and no watering.

    yes, kerb, these are mostly maple leaves and no oak, some pine needles mixed in.

    The Makita 4 stroke backpack I got from tylertool and CPO online:

    Biggest issue is whether new grass has an 'established enough' root system to withstand all the heaving of the soil due to the numerous freezings/thawings over the course of a typical Winter.
    True, but sort of besides the point yea, if someone seeds late, it may grow, and the cold is not actually a problem for the tiny roots but the problem is as you said the ground expands and contracts so much that the tiny roots may just pop out. That's besides the point that if grown so late that the roots won't have much Fall weather to develop - it's basically like starting the growing and then pausing it when it goes dormant around mid-late Nov and then it restarts again in spring, so it's only giving a couple weeks head start VS just starting in Spring to begin with. Plus growing it in late Fall adds the chance of snowmold, walking on it, frost heave etc, it's not really an advantage to grow so late in Fall.

    sorry long and confusing;/
    note the first pics I posted of mulching leaves over %35 new grass, no leaves had been sitting on that area for weeks, unlike the pics with the netted pile had. IOW the newly planted (%35) spot didn't have it so bad.

    leaves (2).JPG

    leaves (1).JPG
    RigglePLC, KerbDMK and sjessen like this.

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