Red Pure Auto CBD

I think the size difference is just genetics, myself... but your plants look as if you're feeding them (as @Roberts said) and at this point in an autoflower's life, any nutes are too much OR your soil is too rich! Autos don't like/don't need nutes for the first few weeks of their lives. This could actually do the opposite of what you give nutes for - it could stunt them! But I disagree with him about the PH - it's spot on. I AM a little concerned that you've got these ladies in such small pots - it means you're going to have to transplant and autos really hate being transplanted - it's quite a shock to them unless it's done very, very carefully so as to not disturb the root system at all.. Autos should always be planted in the pot they're going to finish in! But as for the size... that's genetics! Good luck!

High Yasai, The purple colour is due genetics! They will look really beautiful and there is nothing to worry about! Happy Growing! 😋