Mulching with Grass Clippings

I got an email following my last post about the lawnmower asking basically why I was mowing the field rather than letting some sheep on it. Incidentally you can always use the comments section below to ask questions relevant to the topic, rather than an email.

The answer is two fold. Firstly, I’d have to fence off the raised beds, comfrey plot and some sapling trees or the sheep would devour them. That’s a fairly big job and fencing isn’t cheap.

Grass clippings mulch around jostaberry and redcurrant bushes

Grass clippings mulch around jostaberry and redcurrant bushes

The other reason is I want the grass clippings. Generally gardeners look on grass clippings a problem. When you’ve a large amount, they become hard to compost, forming pads across the bin that seem to take an age to actually rot down. Many actually put them in the garden waste bin and even pay to have them taken away!

Composting Grass vs Mulching

You can compost grass if you can mix it with enough other materials but for my money it’s really useful as a mulch. Laid on thickly enough, I’d say 15cm or 6” in proper money minimum, it suppresses weed growth. Not all of them, but most of them. Those that do pop through can easily be hoed off under the mulch and will, eventually, die off.

A mulch also helps retain water in the soil by stopping evaporation at the surface which draws up from below by capillary action. When it does rain, the rain is initially absorbed by the mulch and then trickles down into soil below. This gives much better penetration and prevents run-off.

Over time, the grass mulch is taken into the soil by earthworms which are so valuable and important to good soil management. Because it shelters the soil below, it encourages the worms to come up. The additional humus it will form should help to increase the worm population.

Most of the mulched areas I have are around the fruit bushes so cultivating in the way of digging is likely to damage the roots, something my friendly worms aren’t going to do.

In the spring add a layer of garden compost and or well rotted manure as thick as you can afford over any remaining mulch. Mulch again over the compost layer.

With very poor soils, like mine is currently, a spring feed in addition to the compost is beneficial. Fish, blood & bone or pelleted chicken manures are good. A slow-release general purpose fertiliser is a good alternative.

Check pH

Do check the pH every couple of years and if necessary apply lime in the autumn. The winter rains will wash the lime down into the soil below.

In ten years or so, the bushes will need pulling out and replacing. By this time, hopefully the soil will be much improved and benefit from digging over or rotavating prior to re-planting.

Last notes

If the grass has grown so long it’s formed seeds then your mulch could be seeding the protected area with grass, not the best plan. Hot composting if possible is a better plan.

Never use commercial ‘Weed & Feed’ for your lawn without double checking the usage instructions. Usually the weedkiller element is persistent and your lawn clippings will be toxic for plants other than grass for a long time. Even composted, the chemical lingers.

Posted in Allotment Garden Diary
11 comments on “Mulching with Grass Clippings
  1. jane says:

    Had some badly frosted early potaoes in April, so I covered them with about 8″ of fresh grass clippings and within a few days they were well on the way and poking their leaves out again. Must have been real cosy under there!

  2. jennifer jean says:

    I have piles of grass from cuttings over the last three months; can I use that in preference to fresh cut mowings?

  3. jennifer jean says:

    I live on a once used peat bog and have 70 plus trees, most grown from cuttings but doing well; should I mulch these with grass cuttings also?

  4. John Harrison says:

    Jennifer – depends on condition of the grass and what benefit you need with your trees.

  5. jennifer jean says:

    the grass was good when cut but it has been piled for the last three-to-six weeks; I did turn it but it is now at the stoogy stage so I need to do something with it. The trees all look as though they could do with mulching to keep weeds at bay and to allow moisture gently

  6. Brian McGraw says:

    Hi John,

    Do you find any problem with grass mulching attracting or increasing slug activity?

  7. Karen Elder says:

    Can I use grass clippings for mulching my asparagus bed? Should I feed it first with blood fish and bone? The soil is not particularly good and on the dry side.

  8. Christina Abbott says:

    Just read this. Im interested to know if I can heavily grass mulch my asparagus bed for the winter?

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