My mother grew rhubarb in her small kitchen garden. She never made wine with it though. She mostly made rhubarb cake, bread, or cookies.
I thought it would be fun to find a recipe for wine:
250ml white grape juice concentrate
1 sachet general-purpose white wine yeast
1 tsp yeast nutrient
Wash the rhubarb, then chop finely into 6mm lengths. Place in a sterilized, food-grade bucket and stir in the sugar. Cover with a lid or a clean tea towel and leave for three days.
Crush the pulp with the end of a rolling pin then stir in three litres of boiled but cooled water. Strain through sterilised muslin into another clean bucket, add the grape juice concentrate and make it up to 4.5 litres with more water. Add the yeast (activate it if necessary first) and the yeast nutrient.
Cover and leave for a week. Siphon into a clean demijohn and add a bubble trap.
After three or four weeks "rack off" into another demijohn (this disposes of the muddy stuff at the bottom which can taint the wine). Any shortfall should be made up with a sugar syrup made from boiled water, three parts, to sugar, one part, and allowed to cool.
When all fermentation has stopped siphon into clean bottles. It is ready immediately though patience may have its reward.