What is a litre of flowers, well it is usually considered to be flower heads gently pressed down in a container.

One recipe draws the flavour from the flowers with hot water then carries on for four days using cambden tablets to stop fermentation. Other one goes straight to the ferment.

One uses raisins t'other uses grape juice concentrate, this is to provide body/vinosity. Without this the wine would be strong (with enough sugar added) and perfumed but thin.

I would recommend that the must is covered at all times to prevent bacterial invasions. Even if the first ferment is vigorous just leave a space in the bin for the head.
One thing I remember is that immersing the flower heads in water in netting first allows the bugs to crawl off, there may be some.