The theme of this poem is feminine beauty, but a beauty which is inaccessible. The poet is describing a beautiful woman, using a rich variety of symbols (different flowers, fruits, pearls and so on) to emphasise her charms, but this woman is also unresponsive to men's appeals, at least for the time being. This is symbolised by her lips which are described as cherries, but these cherries not yet 'ripe' for kissing. She is not ready yet to respond to a lover. The sense of her beauty carries overtones of something that is forbidden; the reference to the 'garden' in her face perhaps carries echoes of the Biblical Garden of Eden which was perfect to begin with, but where Adam and Eve later fell into sin. The poem thus carries an undertone of warning, that any man who finally gets this beautiful woman might have to pay a price.
The central theme of this excellent poem is the conflict between artifice and reality. This poem initially may look like a very common Elizabethan Petrarchan poem in praise of a woman's beauty as elaborate devices are used to describe the woman in the poem and her elegance and sophistication. However, a closer look reveals that this is a rather superficial approach to the poem. Note the following lines:
They look like rose-buds fill'd with snow;
Yet them nor peer nor prince can buy
Till 'Cherry-ripe' themselves do cry.
The use of the word "buy" and the metaphor that compares the woman to fruit for sale clearly shows that the woman and the speaker of the poem are well aware that actually, what is going on is that the woman is only going to "sell" herself to the highest bidder. The artifice of beauty and praise of that beauty is stripped away as the economic and mercantile motives behind marriage are exposed. The initial stanza and the way in which the poet praises the beauty of the woman are therefore somewhat lacking in sincerity. Although the speaker seems happy to play the part of the courtly lover, at the same time he is well aware of the reality of the situation: marriage in his context was an economic settlement that shows the materialistic side of his society, however much beauty was praised.