What is the most important poetic technique used in this poem?
The most significant poetic technique used in this poem is metaphor. The speaker of the poem describes a gardener “caring” for a bonsai tree. The gardener appears to speak lovingly to the tree, but he is actually being quite condescending.
Simply put, to use a metaphor, you say one thing and you mean another. There are two parts to the metaphor: the vehicle and the tenor. The vehicle is what is directly stated (bonsai) and the tenor is what is meant (woman). In this poem, the speaker talks about the the bonsai being domestic, weak, bound and crippled. This is a metaphor for the historical mistreatment of women, more so prior to the Civil Rights Movement of the 1960s.
You could also say that this is an analogy, comparing one thing to another: the way the bonsai is kept from growing and the way women were kept from certain jobs and equal wages.
Personification is also used because the bonsai is given human attributes, with “hair in curlers” being the most obvious personification. It is so obvious, in fact, that you could say this line is no longer personified and no longer part of the metaphor. Rather, it is an overt statement that women have been the tenor of the poem.