Purple northern lights?

okay so i have some northern lights that i noticed today has started to turn purple... is that normal? lol is there anything i can do to bring out the purple more? i also have some querkle that is already pretty purple but i'd like it to be more so lol... i've attached a pic of each...

I heard late in the cycle they start to turn purple on the edge of the leaves looking good!!!

Colder temps at night often bring out the purple in plants. Who's the breeder of your N.L.?

Don't know who the breeder is... I picked them up at a dispensory