tyler_ hobbyist I've done some research into what makes flowers turn the colors they do, and I found an interesting article about how a group of scientists were able to alter the genes of roses in order to produce a rose with blue hues (which they never naturally show in the wild):
https://academic.oup.com/pcp/article...d-Biosynthetic
Apparently there's tons of genes that we know of that affect flower color. One of the pigments that gives a blue or purple hue is called an
Anthocyanin. Anthocyanins are already located in the plant, but the idea is you want more Anthocyanin than chlorophyll (which makes buds or leaves appear green).
So in the experiment they altered the genes of the rose to express more of a blue color by getting the roses to produce more
delphinidin which turns into the pigment Anthocyanin. They did this by altering a gene so it produced more of the Flavonoid
3',5'-hydroxylase (often referred to as
F3'5'H).
Producing more of the flavonoid
F3'5'H caused the plant to produce more delphinin, which turned into red-blue Anthocyanin. Anthocyanin turns blue if it's exposed to a high-pH environment in the plant tissue.
It makes me wonder if giving the flavonoid
F3'5'H directly to the plant (either through the roots or foliar spray) may alter the color of the flowers by increasing the amount of delphinidin being produced. Or maybe you could even give the plant delphinidin directly.
I also found out that the pH of the flowers or plant tissue had an effect on the final color, which I found very interesting. Apparently delphinidin is a natural pH indicator, sort of like the drops we use to test pH. If it's in a basic/alkaline environment it turns blue, and in an acidic environment it turns red. I have no idea what changes the pH within the flower tissue, and I doubt it's as direct as changing the pH of the roots, but you need both an acidic flower environment
and plenty delphinidin in order to get the blue/purple to show.
Just as a side note, I tried to find out what's in
Purple Maxx (which you were saying turned your stems purple). I found
this Youtube video from a nutrient supplier, which says Purple Maxx has two active ingredients:
Methyl jasmonate and
Triacontanol. It also has
Potassium Hydroxide listed as an ingredient on the label.