On the coffee grounds issuečI have done a bit of this in small trials
myself. Here in Minnesota, I experienced increase growth of bacteria
in the soil (like a green fungus cover) that was not advantageous to
the plants. Coffee grounds are supposed to act like peat moss and keep
moisture in the soil. My experience was the opposite, it dure moisture
from the plants.
Perhaps a coffee "tea" like a "manure tea" would be better. Also, I
think composting with other organic matter would be advantageous.
Please tell your gardener to start out in a test patch before
potentially ruining an entire year's crop.