Regarding variegation

Regarding variegation

Hello everyone, I got two variegated peppermint plants in April, and they've grown pretty well. However, up till now, only a small portion of one of the plants have acquired the variegation which was supposed to come with it, even though both pots are placed at the same place, and watered with the same frequency etc. Would anyone be able to share how I can induce the plant to produce more variegation? Thanks in advance for any help.
Attracting Butterflies

Attracting Butterflies

Changes

Changes

My new apartment!

My new apartment!

my room :)

my room :)

Porn!

Porn!

Healthy Cheap Eats Part I: Parmesan Fish Sticks

Healthy Cheap Eats Part I: Parmesan Fish Sticks