I love grass clippings! Can't get enough of 'em.
That's not just me being rhetorical but a statement of fact: I can never get enough grass clippings. Grass chopped up by mowers maketh up my garden. Year in year out in all weathers I've collected and distributed cut grasses atop my garden beds.
This is mulching per the good graces of the local lawn mowing industry. I have guys working for me gratis.
I save them tip fees and they deliver me mulch. All I have to do it barrow it from nature strip to garden bed.
I've been lawn clipping dependent for years. This is my second garden built from lawn detritus.
The sheer scale of the amount of cut green material I've thrown on my garden beds may have to be my little secret because dessicated grass quickly rots down to a shadow of its former self.
It's a total Sisyphusian task. [See image] I'm always just one step ahead of exposed raw earth...which I just gotta cover with still more mulch material.
But after a few years and all those wheelbarrow loads ... my yellowish almost greyish sand has changed to dark grey and black loam while recruiting biota big time.
En route I've learnt a thing or two about mulching and mulching with grass clippings especially.
Lesson #1 : Plop Plop
When distributing grass clipping atop the garden beds throw it down in handfuls so that the surface of the mulch is undulated and pitted. You don't want a flat surface or even a convex one. You want your mulch to break down unevenly so that any precipitation enters the mesh of fibres and percolates through to the soil underneath. Undulation rules.
Lesson #2 : Tease it up
Depending on the weather and the condition of the grass on its arrival, the clippings may tend to lock together and create a sort of mat. This can cause the soil underneath to heat up and may prevent moisture seeping through. So you need to tease up the grass cover as though you are brushing it. Separate the fibres, fluff up the grass hairdo and aerate the mulch. I use my hands and pull any weeds at the same time.
Lesson #3 : No dust
In dry weather conditions cut grass mulch will turn to dust. This is all part of the break down process. The solution is to cover the pulverised grasses with fresh mowings. But because the weather is indeed dry -- and we're talking June and July (here in South East Queensland) for example -- your grass clipping supply may be very low indeed because grass doesn't grow without rain and if it don't grow it don't get mowed and your supply will also dry up.
So you need to plan ahead and as the dry conditions kick in you need to deepen your mulch layer: pile up the grass so that you have leeway in the break down. Watering the mulch will also keep down the penchant to dust and ironically slow down the process .
Lesson #4 : Fertilize
You can read the stuff on the N:P:K of grass clippings and angst over it if you like. Since I'm reliant on the green stuff I've experimented with many throw-on additives deployed to fertilise the garden beds. But I always suspect that I am being wasteful of my resources. It just sits there atop the beds like dollops on a carpet...and dries out to pith.
This is why I seriously explored trench/pit mulching in preference to demanding too much of my sheet mulching habits.Nonetheless, after some experimentation I prefer to 'top dress' my mulch with Blood and Bone (+potash). After sprinkling Blood and Bone over the mulch beds, a quick fluff up of the grass clippings will distribute the ground particles to the soil below. Preferable to 'hosing in'.
Lesson #5 : Weeds
If you are gonna use grass clippings as mulch you are sure to be importing weeds into your garden.
My experience has been that if you keep layering on the cut grass you are usually one step ahead of the weeds as you shade them out. But they occasionally will root and they will spread.
Every now and then I pull them...but the norm is that one species is the feral one so you get to know its habits. That's the irony you see: I may get grass clippings mowed from a wide local regional arc, but the weeds I get are usually just the one or two varieties.
Compared to what I got when I laid out locally collected manures -- especially horse -- give me the grass clipping weeds anyday. I got some real nasties from the manures taken from local farms.In comparison, my grass harvest was benign.
This is one reason why I now prefer to bury my manures in pits rather than let them rest on the surface of the soil.
Lesson #6 : Seedlings
My mulch layer is preferably deep. So when it comes to planting I find that you need to create a pit in the mulch in order to plant your seedling or seed. Pull the mulch aside, embed your plant, and...this is where a problem may kick in.
Ideally you'd flag your seed or seedling: but so far I've not found a foolproof method for doing this. I don't block plant, so the bigger the plant is/the more chance there is that I'll continue to know it's there. So planting in mulch has its drawbacks.
My garden beds are 'busy' ...and there isn't much order about them. So marking off what I do -- so that I continue to register the fact -- is still a problem. This is exacerbated by the thickness of the mulch layer.
Nonetheless, a deep mulch layer will also serve as a wind break for your seedling., so with that in mind you could look at your plantings as taking place at the base of a pit walls all around..