Originally titled ‘Swinging Birches’, the poem ‘Birches’ is one of Robert Frost’s most widely anthologised and studied poems, first published in 1915. Although Frost’s style is often direct and accessible, his poems are subtle and sometimes even ambiguous in their effects, so some words of analysis may be of use here. You can read ‘Birches’ here before proceeding to our analysis of the poem below.
‘Birches’ draws on Robert Frost’s childhood memories of swinging on birch trees as a boy. In summary, the poem is a meditation on these trees, which are supple (i.e. easily bent) but strong (not easily broken). Contrasting the birches with ‘straighter darker trees’ which surround them, Frost says he likes to think they are bent because a boy has been swinging on them. But he knows this is probably not the reason the birches bend: nature, and in particular that common feature of Frost’s poem (aptly, given his surname), cold wintry weather, is probably responsible.
Frost describes how birches, after an ice-storm, ‘click upon themselves’, when they are loaded down with ice on a winter morning. As the day begins to warm up, the sun causes the ice to melt, and the birches shed ‘crystal shells’ of ice, like ‘heaps of broken glass’ fallen from the 
glass dome of heaven. Even if the birches are ‘dragged’ down to the level of the withered bracken near the ground, the birches don’t appear to break, although they don’t straighten up easily once they have been bent really low.
Frost uses vivid and unusual imagery to describe the appearance of the birches: the simile likening the bent birches to ‘girls on hands and knees’, drying their hair in the sun, is especially memorable. It anthropomorphises the trees, but it also reinforces the speaker’s association between the birches and childhood (his preference for believing, even in the face of contrary evidence, that the birches are bent because of boys riding them for play).
It is at this moment during the speaker’s fanciful musings that ‘Truth’ (personified with a capital T) breaks in on his reverie: in other words, the speaker knew he couldn’t entertain the romanticised notion for long that the birches had been bent by boys having fun among them, and he knows, deep down, that the ice-storm was the more likely cause. This bringing-down-to-earth of romantic attitudes towards nature is a common feature of Robert Frost’s poetry.
However, Frost quickly returns to entertaining the idea of a small boy, living in a rural area where he can’t join or form a baseball team with other boys his age, discovering the joys of riding the birches: taking the ‘stiffness’ out of them one by one. The emphasis is on play as a way of learning: a boy growing up in a town may ‘learn baseball’, but Frost’s imaginary youth ‘learned all there was / To learn’ about judging how long he should remain on the birch before jumping off.
We then learn (as it were) that Frost’s speaker can entertain this image at such length because he himself used to swing on birches as a boy: be is reliving his childhood freedom and joy through the memory. He would like to go back to such boyish innocence. When nature presents problems – he walks through a wood without a clear path and gets a face full of cobwebs, or a twig lashes across his eye – he dreams of getting back to the simplicity of birches, which he had learned to judge and bring under his control.
However, when Frost (or his poem’s speaker, at least) says that he would like to ‘come back to [nature] and begin over’, there’s a sense of wistfulness that extends far greater than birch-swinging, hinting at the adult’s vain yearning to return to childhood and live his life over again. However, the level-headed reasonableness returns, and the speaker says that he doesn’t really want to leave nature behind, as ‘Earth’s the right place for love’. Nevertheless, when his time to die does come, he’d like to die while climbing a birch tree, climbing towards heaven (note the rare use of italics to emphasise the idea of moving away from the earth, and nature, towards death), until the birch tree swung him back down to earth at the last minute.
‘Birches’ is written in blank verse: unrhymed iambic pentameter. This means that there are (usually) ten syllables per line, with the syllables arranged into five metrical feet, in this case iambs, which comprise an unstressed syllable followed by a stressed one. Frost was fond of using blank verse in his poetry: since it is close to the rhythms of regular human speech in the English language, it reflects his homespun, colloquial style. In the case of ‘Birches’, the unrhymed iambic pentameter rhythm suits the poem’s meditative, reflective mode.