gradient filled plot panels with facet_wrap

I did the following barchart by using:

ggplot(yearplot,aes(x=reorder(vE,release.year), y=difference,fill=PAR,label=signif.))  + 
  geom_bar(stat='identity',position = "dodge",  size=3 ,alpha=1)  +
  geom_text(aes(x = vE, y = difference+0.03 , label = format(signif., nsmall = 0, scientific = FALSE)), 
  color="black",size=6) +
  xlab("Genotypen")+
  ylab("Differenz")+
  theme_bw()+
  ylim(-0.2,0.2)+
  facet_wrap(~number,labeller = labeller(number=date.wrap),nrow=1)+
  coord_flip()+
  scale_fill_gradient2(name="PAR \n[mol/m² s]",low="darkblue",mid = "orange1",high = "orangered4",limits=c(1200, 2100),midpoint = 1200)+
  theme(legend.position="top")+
  theme(legend.key.size = unit(3,"line"),
        legend.title = element_text(size = 16,face="bold"),
        legend.text = element_text(size = 14))+
  theme(axis.text=element_text(size=14,face="bold"),
        axis.title=element_text(size=16,face="bold"),
        strip.text = element_text(size=16,face="bold"))

I would like to add temperature values as gradient filled plot panels, similar to the PAR values. So for example the plot panel of june 1 is light green and june 6 is dark green and the rest between. In the data frame is one temperature value for each day. Is there any possibilty to do that?