Well..........
First I would make absolutely sure that they are edible.......
I know rose-petals are and I do know elderflowers are. I am not sure about citrus as they do not grow around here.
Next.
The infusion.
I know that you need just a few elderflowers to make a lot of wine.
To be exact 1 liter flowers (75 gram) for 10 liter wine.
http://wijnmaker.blogspot.com/2009/05/vlierbloesemwijn-2-elderflowerwine-2.html
Do not overdo it otherwise the flavor would be much to strong to be pleasant.
Elderflowers are very fragant.
For rose petals you will need much more. The amount is one liter flowers on 1 liter water.
My rose petal wine recipe will be published somewhere later this year.....
So what I am trying to say is that you need to determine how much flowers you would need to make a decent must.
Actually there is a good way to do some testing.
Pick as much flowers as you can get.
Put them in zip-lock bags of each 1 liter (75 gram) and freeze them.
That way you can do tests with part of the flowers without having to worry that the rest would spoil before you can make the must.
Most flowers freeze well. I know rose petals do and I do know dandelions do. I am testing elderflowers as we speak.
Now start making an infusion of 1 liter water with 75 gram flowers.
Make another infusion of 1 liter with 35 gram, and yet another with 1 liter and 10 gram flowers.
Let each soak for a few days.
Taste every day. After 4 days sieve and taste.
Now you will know what kind of amount you will need to make the proper must with the right flavor.
Make the real must a bit stronger as the infusion you made. As flavor will mellow out during fermentation and aging.
Now do the calcs.
This will be a white wine so:
Flowers do not have acid so add acid to .6
Bring SG to about 1.085 being 11% alcohol.
Do not overdo the alcohol......
I would add double the amount of nutrients that the packaging describes. Flowers provide for nothing.
I would boil banana's (without peel) and start with adding the banana juice to the flowers. Banana's (without peel) will loose their flavor but will bring body.
about 3 to 4 full ripe (black) banana's submerged in water would do per gallon wine.
Next bring the water up to the desired volume of the must with 1 liter less.
The 1 liter less is preserved.
Why ???
I would make a yeast starter, just like on my web-site and add that.
http://wijnmaker.blogspot.com/2007/08/gist-starter-yeast-starter.html
That would bring a volume of 1 liter along.
You could add some tannin as I presume the flowers would not have any. If you do not have tannin around use strong black tea (about a cup per gallon).
As I almost never use tannin in my own wines this is a matter of choice. I personally think that fruit wines do not need to resemble grape wines. But that is a matter of taste.
Next I would pulp-ferment as long as I did the infusion.
Open fermentation in a bin with a cheesecloth on top.
After the desired days pulp-fermentation use the bucket press
http://wijnmaker.blogspot.com/2008/03/bouw-een-emmerzeef-building-bucket.html
bring it over to a carboy.
That's just my approach.
Luc