I'm looking for a novel. It was fairly thick for a young child (maybe 200-300 pages), and I read it in the early-mid 2000's, around 2004.
The story revolved around a rhubarb farm that grew enormous rhubarb, with other magical properties. In the center of the farm there is a towering carousel-ish structure. This was all treated in a very Fablehaven-esque manner, with only a few people allowed on the farm.
The main plot point is some sort of supernatural storm brewing that would desiccate the farm? Sadly, I don't remember much about this.
The cover is a shot from the perspective of of the enormous fair ride towering over the farm, showing enormous rhubarb far below as well as the storm brewing in the distance.
I think the main character is a young girl.