Do I need to transform my data before PCA?

#1
Hi, I have 18 variables (soil biogeochemical properties) that I want to put through a PCA. Some variables have large units (e.g. %) and some small (e.g. mg C/L). Should I transform the larger units before running them through PCA? Some of the variables also have non-normal data; should I also transform those?
Thanks :)