[m1ckz]

is it ok to mulch plants with fresh grass cuttings from the mower    or    will this rot them   thanx

[arugula]

Yes you can, but not too thickly and if you've recently applied any sort of weedkiller to your lawn, I wouldn't use the clippings.

[Hobnails]

I mulch around outdoor tomatoes with a 10 cm layer mostly to prevent the ground drying
out in the summer heat. I water the plants direct to the root through a cut away plastic milk bottle.
I do pile the clippings for a couple of days to let them heat up before using them.
Works well for me as I have no water on the plot other than what I catch or take with.
at the end of the season, it makes good dry material for the compost heap.
On the downside- slugs love it under the grass cover.