Snapdragon Question

Snapdragon Question

Last year I discovered a young, single-stemmed, purple Snapdragon growing out of our garage wall. I managed to ease it out with the root system intact and transplanted it into one of my flower borders, where it developed, spread and thrived. This year it's gigantic and absolutely stunning... but why is it red instead of purple? I don't mind it being red, as red and purple are two of my three favourite colours; I'm just wondering if something in our clay soil could have caused this to happen?
I decided to finally post some pictures!

I decided to finally post some pictures!

input for strawberries and guinea pig poop

input for strawberries and guinea pig poop

Working on the farm, Photos of the Student Organic Farm at MSU

Working on the farm, Photos of the Student Organic Farm at MSU

My lovely garden-both veggie and roses…

My lovely garden-both veggie and roses…

Lounge/den too

Lounge/den too

Yet another plant ID.

Yet another plant ID.