using grass cuttings as a mulch around orchard trees

[TheField]

If we go for a cut-collect option for our orchard grass, what's the best thing to do with the cuttings? Just a big heap that will hopefully compost down (or spontaneously combust!)? Or would it make a useful mulch around the orchard trees? Any reasons not to do this, from the trees' perspective?

[nickygradyscott]

I use grass cuttings as a mulch all the time. don't pile them up against the trunks of the trees. If you compost them you must layer or mix with something to allow airflow. Haystacks could spontaneously combust if the hay was not properly dried. it's the balance between air and water that created the ideal conditions for bacterial to exponentially multiply and generate that heat. You can also put very thin layers (1 inch) of mowings and sandwich with cardboard to make 'cardboard mould' (like leafmould). I use this technique with no-dig 'lasagna' gardening as well and layer in other materials too to create no-dig beds.

[Donna Cox]

We've been using a cut and collect mower, with a high tip, for our orchard grass for the last few years. If it's a flower-rich site that has set seed you could use some of the clippings to resow other areas (would need to use them immediately though, transferring to the prepared area straight away). I've never had a problem with a grass heap combusting. Heaping grass can take up a fair amount of space to begin with so needs careful placement. I have used some of it to mulch newly planted trees in the field, avoiding, as Nicky says, the trunk. The heap left creates a valuable wildlife habitat in its own right and will reduce in volume quickly.

[Amy]

I cut the fields in October when the grass and flower stems are relatively dead and dry, and many seeds have fallen. I leave my meadow cuttings from October until the following spring in a large heap.

As Donna says, it needs careful placement. Move it only the once if you can. I found it is better to take the time to trundle up and down the field to leave the cuttings in the final place, than to leave it in heaps around the fields. If you leave the fresh cuttings until the rain falls, then awful fusty moulds develop and you won't want to breathe them in whilst moving the heap. So move the cuttings before it rains. If you leave the heap for several weeks or months, then it is more difficult to move without disturbing the soil beneath, and one ends up with soil mixed up in the heap. This might be ok if you are digging it in, but if used as a mulch, the soil will encourage weeds to germinate and it just generates more work.

Over time, the heap reduces in height. I persuade someone with a small digger to turn it and heap it up again, so it rots down better. You wouldn't want to do this by hand because it is very heavy and sticks together, and because of the moulds.

I don't bother to mix anything else into it, it just rots down a little, in large clumps of stems. If grass sprouts on the surface, I just turn the clod upside down when I see it. So, by spring, it isn't well rotted garden compost, but it is a very useful, fairly dry, coarse, almost strawy, mulch, (and the moulds only linger in the remaining damp patches and don't seem to have spores by then - just turn over the patches to let them dry out).

I apply it as an annual mulch on flower beds and around orchard trees, from late winter into early summer, as and when I can get to it. (I don't bother to feed my orchard trees, but if you do, then obviously apply the mulch after feeding, or pull the mulch aside to scatter feed and then replace it. It's in large dryish clumps by then, so it is very easy to handle.) It's Wonderful stuff. It keeps the moisture in and prevents weeds from germinating. I hardly have to touch those borders for the rest of the year.

I have had very little trouble with it - I do have some new knapweed plants which I have left in place, and they look good, and a meadow sweet once appeared and spread 12" and didn't like the drier conditions of a flower bed so became mildewy and I dug it out. I also have a plant of yellow meadow vetchling which runs about 12" around in my pink themed flower border and is a little more of a nuisance, but I just haven't got around to digging it out yet. But these are isolated incidences in several long flower borders and an orchard.

I asked the RHS about this and about using fresh lawn clippings as a mulch. As others have said, the crucial thing is to keep the mulch away from the tree stems. The RHS says spread the mulch a few inches deep, but not 6" or more as supposedly it stops oxygen reaching the soil. Ideally, spread the mulch out from a circle 3" away from the trunk, up to the tree canopy edge, and a little beyond, if you have the space - this is where the tree feeding roots are.

It saves hours of work.

Info on tree roots https://www.trees.org.uk/Trees.org.uk/f ... 16aa9e.pdf