The first two things any community makes, according to the narrator of The Scarlet Letter by Nathaniel Hawthorne, are a cemetery and a prison. This is an indication, of course, of two things that never change in human nature. First is man's tendency to sin and society's need to punish; second is the inevitability of death for all men. It is the prison door which captures our attention for this question and, until the end, this novel.

Right next to the prison door, on one side and almost flush against the threshold of the prison, is a wild rose bush. Every prisoner who goes in or out of the building must see it. To the criminal (sinner) who enters the prison, it is a "fragran[t] and fragile" reminder that beauty still exists; for the "condemned criminal as he [comes] forth to his doom," the sight of the delicate petals is a reminder of Nature's pity (sympathy) for him.

The narrator tells us this rose bush "has been kept alive in history," though he cannot attest to the source of its being there and will not presume to guess. He does say, in the last words of chapter one: 

Finding it so directly on the threshold of our narrative, which is now about to issue from that inauspicious portal, we could hardly do otherwise than pluck one of its flowers and present it to the reader. It may serve, let us hope, to symbolize some sweet moral blossom, that may be found along the track, or relieve the darkening close of a tale of human frailty and sorrow.

In the narrator's words, then, the rose symbolizes a luminescent (bright) touch of morality in this story, or perhaps it will serve as a pure and colorful spot of relief in this woeful tail of "frailty and sorrow." Another way to look at the rose is as a symbol of hope to all who leave or enter the prison, a place which represents sin, condemnation, and punishment. It is as if Nature wants to offer at least a glimmer, a fragile petal of hope to all who feel hopeless and condemned. 

As the story progresses, the rose serves as a kind of relief from the weight of darkness and sin.

At the end of the first chapter, the narrator describes the prison from which Hester enters and then, later, into which she recedes, as the “black flower of civilized society.” Earlier, he noted that two of the first provisions that any new community makes are for a cemetery and a prison, implying that there are two certainties in any community: people will die and people will commit crimes. Those law-breaking sinners will need to be punished by society, and so the prison is constructed. The prison, this “black flower,” is juxtaposed with the “wild rose-bush” that grows just beside its heavy iron-studded door. This rose bush is covered with “delicate gems,” which the narrator claims

offer their fragrance and fragile beauty to the prisoner as he went in, and to the condemned criminal as he came forth to his doom, in token that the deep heart of Nature could pity and be kind to him.

The prison is an indication of the lack of mercy and compassion that will be extended to sinners by this Puritan society. The rose bush, however, by growing nearby and producing such beautiful blooms, seems to symbolize the idea that nature does not judge the sinner as society does and that nature will offer kindnesses no matter what.

Further, the narrator notes that the rose bush remains “alive in history” despite the death of the “gigantic pines and oaks” that once overshadowed it. Thus, nature and its will are of much longer duration than any society. The narrator concludes the chapter by suggesting that the roses will “symbolize some sweet moral blossom” that we might find in this story of “human frailty and sorrow.”

The rose-bush, as we learn in chapter one, is a symbol of the redemptive compassion and kindness inherent in the natural world. Man may build cruel prisons and impose harsh laws, but nature, the great equalizer, will bloom in the form of a wild rose-bush outside the prison wall, allowing even the condemned prisoner the mercy of its sweet scent. The rosebush symbolizes the bounty and mercy of nature.

The novel also suggests that saintly people, such as Ann Hutchinson, help nature bloom sweetly: the goodness of nature and the goodness in the hearts of humans are both, symbolically, fertile soils that bring forth sweet flowers.

Pearl, when asked by the governor who made her, will not say "God," which is the obvious answer, but instead announces that she was plucked by Hester from the wild rose-bush that grew outside the prison door.

This may be a theologically shocking response, but it is also a true answer in terms of the novel's symbolism: Pearl is a fruit of the natural goodness and redemptive compassion of God's creation that is symbolized by the rose-bush.

It is through his use of symbolism in The Scarlet Letter that Hawthorne has made one of his most significant contributions to American literature that has been perpetuated throughout the nineteenth and twentieth century.  In Hawthorne's symbolic narrative, the red rose is representative of passion; as such the rose bush outside the prison door--"the black flower of civilized society"-- serves

to symbolize some sweet moral blossom, that may be found along the rack, or relieve the darkening close of a tale of human fraility and sorrow.

This "sweet moral blossom" is the passionate fortitude with which Hester refuses to wither under the scorn of the Puritans who gather in their grey steeple-crowned hats and "sad-colored garments" to watch and scorn her in Chapter I.  In another allusion to the roses by the prison door, in Chapter VIII, when asked by Reverend Wilson who made her, Pearl--knowing her catechism--impishly says that

she had not been made at all, but had been plucked by her mother off the bush of wild roses that grew by the prison door.

Thus, Pearl is the rose and, like the rose, is symbolic, too, of the kind of passion which has accompanied Hester's sin.  The red rose of The Scarlet Letter symbolizes passion and "some sweet moral blossom" in both Hester and in Pearl, who is a symbol herself of Hester's sin of adultery.