How does Sylvia Plath use colour to convey emotion in her poems?

It is evident in Sylvia Plath's poetry that colour is a dominant theme, which she weaves into her poems to help convey certain emotions and other themes. The colours she uses each symbolise something different and occasionally groups of colours to further reiterate these said themes. An example of colour use is in 'Tulips', where the colour white is uses to describe how the speaker feels in the hospital bed. Traditionally, the colour white is used to convey purity, however in 'Tulips', Plath uses it to convey the speaker's current state; the speaker has been stripped of everything that defines her and all that's left is the white colour of the hospital walls, as this is now what defines her.