ggplot: boxplot sort

Question

How do I sort a boxplot in ggplot?

Here's what I'm trying to plot:

qplot(  row.names(pcaDF),pcaDF[,1],data=pcaDF,geom="boxplot") + coord_flip() 

and here's the structure of pcaDF

> str(pcaDF)
'data.frame':   108 obs. of  1 variable:
 $ sort(plotdata[, 1], decreasing = F): num  -5.89 -5.52 -4.66 -4.54 -3.92 ...