In the first stanza, the speaker uses a metaphor when she says that her mother "cooked up her daughters / into girls." This metaphor implies that the mother brought up her daughters as one might cook a good meal, adding virtues and values as one might add ingredients. The metaphor also implies that bringing up children is a delicate process, requiring the careful balancing of lessons and guidelines in the same way a good meal requires the careful balancing of various ingredients.
In the second stanza of the poem, the speaker uses a simile when she says that her mother is as "pale as a witch." The word "witch" has many connotations. A witch is usually associated with evil, which implies that perhaps the speaker thinks that her mother is sometimes cruel. A witch is also associated with magic, which perhaps implies that the speaker thinks that the mother is capable of wonderful, magical things.
Also in the second stanza, the speaker says that her mother is like an anchor "in the midnight storm." This is an example of pathetic fallacy, a literary device whereby the weather is used to reflect the mood of the story or of the characters. Here the "midnight storm" suggests an ominous, troubling mood. The speaker is saying that the mother is like an anchor during troubling, ominous times. In other words, the mother helps her daughters to endure those times.
In the fourth stanza, the speaker uses repetition when she writes three times in successive lines the phrase "Mother I need." The speaker repeats this phrase to emphasize how much she needs her mother. In the third and fourth lines of the same stanza, the speaker says that she needs her mother "as the august earth needs rain." The speaker's meaning here is that she needs her mother as the dry earth needs the rain. The speaker needs her mother to grow and to be healthy just as the dry earth needs the rain in order to be fertile and for crops to grow.