Grass as a mulch, should I or not???

captaindirt(6/7)June 13, 2012

I am confused by what others are telling me so I thought I should pose the question to everyone here and hope that there's others that benifet from this as well.

For the last ten plus years I've multched my lawn because I was told that returning the clippings to the lawn will add nitrogen to the lawn and help it stay nice and green.( and it has done just that)but was told that mulching the garden with clipping would rob the soil of nitrogen. Is grass as a mulch good or bad and if I use grass, how should it be used?

Thanks for all your help.

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Grass is just about ALL nitrogen. (Which is why commercial lawn fertilizers are really high on the K-P-K mix.)

I collect as many bags of grass clippings as I can get all summer long. By summer's end I have added as much as 12 inches of clippings in some parts of my garden (especially around the tomatoes), though a lot of it disintegrates by the end of the summer.

I turn it all under in the fall.

Mulch keeps the soil from drying out. You can't go wrong. And in the summer, grass clippings are the most readily available free mulch material you can find.

    Bookmark   June 13, 2012 at 10:07PM
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My limited experience I think it can be really great when used as a mulch but there are few issues that cause me problems.

When used as mulch it works wonderfully at keeping weeds out but when it is thick enough to do that it also blocks any rainfall. I've checked like after a inch downpour and the soil underneath will be bone dry.

Next it keeps this the weeds beat down but at the same time if there are any weeds that have bagged with the grass it is also reseeding weeds seeds at the same time unless you compost it first. I guess that is why the use thatch for roofs.

I have run the clippings through a wood chipper and it results in an ultra fine mulch. Putting that on lightly on the raised row, just enough to cover and not enough to keep weeds out. I've seen wonderful results the vegi plants and soil underneath. Breaks down fast the soil ends up really rich. But the labor, reseeded weeds and water issues have me going in different directions. Trying to mulch with straw this year.

    Bookmark   June 13, 2012 at 10:47PM
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Recycling your grass clippings right back into where they came forom is a very good idea because those clippings can supply up to 1/2 the Nitrogen needs of your turfgrass. Those clippings can provide up to 1 pound of Nitrogen per 1,000 square feet.
You could also collect the cippings and use them as mulch in your garden and since they have so much Nitrogen they will not "rob the soil of Nitrogen" any more then any other mulch would. If a high Carbon material, wood chips, were to be tilled into the soil, a soil amendment, the Soil Food Web would get busy digesting them using a lot of the available Nitrogen in the soil to do that. However, if those same wood chips were layed on the soil, a mulch, the Soil Food Web would not find it necessary to quickly digest them and they would continue feeding your plants working on the mulch as time allowed.
You can use your grass clippings either place with no qualms depending on what you want to accomplish.

    Bookmark   June 14, 2012 at 6:39AM
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All about Lawns says that 1/3 of the Nitrogen can return to the soil. But in some cases you should bag the grass.

    Bookmark   June 14, 2012 at 6:43PM
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"All About Lawns" also says that those grass clippings might contribute to thatch in the lawn which is not true, jolj.

    Bookmark   June 15, 2012 at 6:30AM
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rhizo_1 (North AL) zone 7

Grass clippings can absolutely contribute to thatch build up in a lawn, kimmsr. It is, indeed, one of the most common causes of thatch.

Some of the factors that contribute to the problem are excess use of high nitrogen fertilizers, grass species, and low soil moisture. The primary factor, though, is not mowing frequently enough to prevent taking too much off at any mowing cycle.

Warm season grasses grow like crazy in the late spring and summer; it can be difficult to keep up with the kind of mowing routine that can prevent the build up of clippings that are too long. Mulching mowers certainly help. But thatch can accumulate in a hurry if the blades from a previous mowing still haven't begun to decompose when it's time to mow again.

I'm all for leaving clippings on the lawn where they can do the most good. That's what we do each and every time that we mow. But we are also aware of the techniques that help prevent thatch and take great care that it does not become a problem. It can be a challenge when the grass is growing like crazy in the high temperatures!

    Bookmark   June 15, 2012 at 2:06PM
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It is not the grass clippings that contirbute to thatch. That is an old idea disproven many years ago.

Here is a link that might be useful: grass clippings and thatch

    Bookmark   June 16, 2012 at 6:48AM
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rhizo_1 (North AL) zone 7

Ok...let's call it a 'mat' comprised of a build-up of undecomposed grass clippings that impedes water infiltration and the exchange of soil/atmospheric gasses. The real point is that infrequent mowing contributes to the formation of this problematic 'mat'.

    Bookmark   June 16, 2012 at 3:04PM
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gardenlen(s/e qld aust)

g'day captaindirt,

no it won't rob nitrogen from the garden if used as mulch, it will if you dig it in then you need to wait for decomposition to occur, grass can form a mat that rain or water can't get through, and it can promote the growth of grass seeds in the garden, so usually better if it is put under some other mulch, but best to just leave it on the lawn.

in all the years well decades i have left clip on the lawn thatching has never been an issue, under thick grass growth it all rots down, that is how it keeps the lawn fed and moist. where we are now the grass has been tractor slashed over the years there is some of the more recent clip sort of thatched but all previous clip is broken down or in the process.

lesson to be learnt cut grass as high as possible, we cut ours 1 notch below maximum.

leaving the clip will not work on bowling green appearance lawns.


Here is a link that might be useful: lens garden page

    Bookmark   June 16, 2012 at 3:23PM
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Rhizo, a good healthy soil under your grass will not allow a "mat" to develop because the Soil Food Web will digest any orgainc matter you put there, especially grass clippings. Where thatch becomes a problem is on lawns that are fed synthetically derived nutrients and are sprayed regularly with poisons to control "weeds" and insects that prefer to grow in poor, mistreated, soils.

    Bookmark   June 17, 2012 at 6:33AM
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rhizo_1 (North AL) zone 7

Grass clippings become much more of an issue with warm season grasses. You may not be familiar with that, kimmsr. C-4 grasses often exhibit tremendous growth surges in the late spring and summer, not because of fertilizer but because of temperature and daylength.

Few people are going to mow twice a week...yet that is really optimum for grasses that are growing at a rapid rate. Once a week mowings can result in clippings that are too long to decompose rapidly, even on that o-so-perfect soil.

Right now, we are mowing twice a week...a schedule that doesn't usually start until early July but everything has been early this year. We use organic liquid fertilizers applied through an EZ-Flo via our sturdy little 'walking' tractor sprinkler. We don't have an irrigation system. Watering, at our home, is done on an only-as-very-much needed basis, in case you are going to accuse me of over watering along with the excess fertilizing, herbicide and insecticide use (NOT!).

This is probably not an issue with our original poster, in his zone 6 climate. C-3 grasses would be the norm in zone 6; they tend to slow down in the heat of the summer.

All I am saying is, some parts of the country, the mowing routine is very important so too much blade is not removed at any one time.

    Bookmark   June 17, 2012 at 11:19PM
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I have built my entire 3 acre garden around the concept of harvesting grass clippings for mulch. I have about 2 acres of lawn, over-seeded with clover as a nitrogen source, and that gets mowed every 8-10 days. I collect the clippings to mulch two dozen fruit trees and the extensive vegetable and flower beds.

When I'm done mulching what I need to, I leave the clippings on the lawn, or pick some up for the compost operation, or mulch out in the tree/shrub border, but that is now well-enough established that its self-mulching.

The mulch will last two seasons around the trees, a single season in the flower/vegetable beds.

Works pretty good.

    Bookmark   June 21, 2012 at 10:40AM
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I like to collect the grass clippings and put them on the garden over newspaper. I am well aware that the lawn suffers by taking the clippings away, but I am more concerned about the vegetable garden. My hope is to someday fertilize the grass (no weed spray) and put the grass clippings on the garden, the best of both worlds, nice looking lawn while adding organic matter, nitrogen, conserving water, weed control in the garden.
Not sure if it will happen this year though. We had decent rains in April, but then it stopped and the lawns are brown and the last couple times I mowed there weren't many clippings so my garden may skip a year with grass clippings. I have also put the clippings on right after mowing using the bagging attachement to my mower(I know it is not "right") but if you only put them an inch or so I haven't had a problem with them heating up too bad

    Bookmark   June 21, 2012 at 12:48PM
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Rhizo, why would you fertilize if your lawn is growing so fast you have to mow twice a week? I haven't applied one ounce of ferts to my lawn in the 3 years I have been here. I mow on the second highest setting and still should mow every 5 days (I only do mow every week).

I allow every other mowing to sit on the lawn for a full day in the heat if possible to dry out. Then I rake it up and apply to the gardens as mulch. When I have mulched everything, every other mowing will go into the composter mixed well with bagged shredded leaves from last fall and whatever kitchen scraps I can throw at it.

My new trick is this. I mow all the grass one way Towards the chute as long as the mower doesn't bog down. Then I mow once the other way to make a nice row of clippings and then continue mowing in one direction after that. I am left with several rows of clippings in the yard that will dry in one good warm non-humid day. I just purchased a tro built leaf shredder vac. So I just take bagged leaves from last year and sprinkle them along the rows of grass and then I suck both up at once with the leaf shredder vac and presto, dried grass clippings and shredded leaves all bagged and ready to apply as a wonderful mulch.

my .02


    Bookmark   June 21, 2012 at 5:03PM
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CH - nifty trick with adding the old leaves to the dried grass & vacuum/shred them for mulch. Do you have use the catch bag or have a way to collect the shredded material into a cart or garbage can? That still sounds like work to me.

My bagged leaves are over a year old now and pretty heavy. I plan to use them for my next batch of seed starting.

Last year we had a new leaf blower/vac/shredder, so we just vacuumed them up & put on the garden beds as we acquired them. Preferred to work with them on dry days and freshly fallen. Wet leaves, wet cool weather, & heavy collection bag made it a bit too heavy for me, but my teen son or husband did fine with it.

I use grass as garden mulch collecting clippings about once a month only and leaving the rest on the grass because we have a mulching blade.

    Bookmark   June 21, 2012 at 8:52PM
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I'm still in my prime, so a little hard work never deters me. Prior to this I would occasionally do the same only run the rows over with the mower and then rake them back up into piles and then wheel barrel them over to the gardens and apply by hand.

The Leaf vac does have a bag so I just Vac up until it's full, and then bring it over by the beds, dump it and apply by hand. Really no other way to do it. Also the leaf vac is self propelled, it's an old troy built model, but it's in great condition.

This is the first year I have used any form of mulch on my veggies. The work I do mulching has cut my weeding by 90% at least. I can weed all 400 SF of raised beds in about an hour. I usually run through it twice a week.

I'm really excited about the leaf vacs capability of chipping up to 4" branches. We get lots of piles throughout my neighborhood. I may not have to by additional mulch ever again. Just chip up all my and my neighbors fallen branches every year. Should be good for top dressing all the mulched flower beds, paths and trees.

Anyways, I digress, grass clippings so far for me, especially when mixed with some shredded leaves have done a wonderful job. I have had no issues with matting or water not penetrating the mulch. Nothing like that.


    Bookmark   June 22, 2012 at 8:56AM
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I was fearful of using lawn clippings as mulch, too... as so many internet articles suggest against it for various reasons.

Personally, I have found absolutely no downside to using clippings as mulch. I started the season using leftover leaves from fall as mulch, but those quickly broke down and something else was needed. Thus, I decided to use the most easily available and cheapest product that I could find, grass clippings.

I applied one "batch" of grass clippings as mulch to my corn plants since they were seedlings. I applied layer approximately 1/4" to 1/2" thick, just enough to cover over the dirt but not enough to mat it up where water can't get to the soil.

No weeds, soil stays moist even days without rain, no bad smells (at least not to me), and one application has lasted well over a month. I planted the corn on May 1, 2012 and most of the plants are well over 7' tall... most of them are just starting to show their tassles, and some of them have silks. I'm not saying only grass clipping mulch made the corn plants grow this well, but I know it definately contributed to keeping the roots cool and moist in my area when it hasn't had a good rain in weeks.

As such, I have since been applying grass clippings as mulch to almost all my other veggies including potatoes, lettuce and basil plants. I have observed similar benefits from these plants as well.

My lawn (where the clippings come from) is doing just fine, even without the extra clippings. I have to mow at least once a week, and this is without rain or additional fertilizer. I also do NOT use any pesticides on either my veggie garden or my lawn.

If this sounds like your situation, I would whole-heartedly recommend using grass clippings as mulch.

The pic is some of the lettuces I grew with grass clippings as mulch. As you can see, they did just fine (and no weeds).

    Bookmark   June 28, 2012 at 5:32PM
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There are many myths about grass clippings as both mulch and recycling them on the lawn that I have heard since the 1950's, none supported by good research, that just hang on especially today with the internet. Some states have laws banning placement of grass clippings, yard waste really, in the trash to be taken to landfills and encouraging people to reuse them on the property they came from. The Agricultural schools in those states have done research that dispells those myths and shows recycling the yard waste on your property is good for the soil.
But we still have many people that prefer to believe the myths.

    Bookmark   June 29, 2012 at 6:40AM
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rhizo_1 (North AL) zone 7

Coconut, warm season grass species have a different metabolic system than (C4) your cool season varieties. They kick into high gear in the heat, growing like crazy whether fertilized or not. But if you don't provide nutritional elements at all, the turf will decline, thin, and become susceptible to lots of problems related to nutritional stress. This is not the case with the cool (C3) varieties.
Some people overdo it.

We know how to achieve a healthy balance of supporting normal growth while still encouraging root development and carb storage. We leave all of the nutrient rich clippings on the lawn, water deeply once per week (if no rain) with our trusty traveling lawn sprinkler (National), apply humates via EZ flow injectors through the hose (via the walking sprinkler), as well as occasional applications of Bovamura or similar. No excess fertilation going on here.

Warm season turf species, stimulated to grow vegetatively by heat and short nights of summer, will begin to slow down as the nights get longer. With the proper balanced support system, the grass plants will be able to store carbon resources in the storage and roots. That will enable a healthy warm season turfgrass species to survive a cold dormant season. By the way, we subscribe to the 'remove no more than one third ' rule for grass. We could mow with less frequency, but it wouldn't be good for the grass. At this time of year, mowing is done every five days or so.
We also set the mower to three inches in this heat and keep those blades sharpened 'like a razor', as my husband says, lol.

I hope that you understand a little bit better about the cultural requirement differences between C3 and C4 turf species.

    Bookmark   June 29, 2012 at 10:14AM
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