Lawn...

[MisterBoy]

Your existing cut grass will, if spread over the lawn as mulch, kill it. But I didn't see if you said what you want to use the space for afterwards... garden, gravel, patio, ...?

 

[Android 07]

Sorry for the late reply.
This is what the lawn looks like.

 

[Harry Bloomfield]

I have a small lawn in my garden and the grass keeps growing very fast.
I do not have the time nor the effort to keep mowing the lawn. What can I do to kill off all the grass? Should I dump bags of sand on top ?

What do you call too fast? Speed of growth depends upon the season, how much rain has fallen and how much sun the grass gets. Mine can sometimes need mowing as often as twice per week, when conditions suit growing and cutting and I have a 1/3 of an acre to try to maintain control of, with around 20 trees.

I use a tractor mower, which makes it fairly effortless, but I don't collect I just let it return the cuttings on top. I have not seen any bad effects from doing that, providing it is spread evenly and cut often enough to avoid clumps of grass sat on top. With only a few inches of soil on top of heavy clay, it can become water-logged in heavy rain, which means the tractor would simply turn it to mud. So there are times when it cannot be cut.

It really needs to be cut now, but it would be silly to take the tractor on it, it is that wet and boggy. It is difficult to even walk on it. Once it is dry enough in the spring, I usually try to go round it several times in the first week, to mulch the long cuttings.