Was the article about hydrangea flowers by chance? Because that has to do with uptake of metals from the soil (aluminum) that occurs particularly at lower pH's and turns the flowers blue. Doesn't apply to daylilies. As far as I'm aware the "pink socks" in daylilies occur whatever the soil pH. Cell pH is another question. Can you post a link to the article?
Temperature can also affect anthocyanin pigment.
@admmad would be the person to ask about this.
Edit: no I mis-read and am misleading you, hydrangea flowers are blue at low pH and pink at high pH and sort of muddy purply-pink in between so your article obviously was not about hydrangeas. Sorry.
