The Seeds of Wither (The Chemical Gardens #1.5) by Lauren DeStefano
The Seeds of Wither offers a VERY brief glimpse into the life of Rose, Linden's first wife and true love. I don't think you really get anything more out of this short than you do through Rose's conversations with Rhine in Wither, hence the 1 star rating.
The book is not worth the 99 cents it costs and I actually ended up returning it. It consists mostly of a preview of Wither and Fever and the preview of Fever is the same as the one at the end of Wither, so not really worth the money.