The struggle between the Giant and the children over the garden can be read as an allegory about the Irish land struggle. Ireland was still a part of the United Kingdom in 1888, when Wilde published "The Selfish Giant." In fact, the decade leading up to the story's publication marked an important period of civil unrest in Irish history. Starting in 1879, the Irish Land War was a period of agrarian agitation aimed at land reform. At the time, Irish land ownership was concentrated between a relatively small number of people, many of whom were English absentee landlords. For this reason, Irish tenant farmers engaged in a campaign whose main aim was for the people who worked the land to be the ones who owned it.
In relation to this history, it is significant that the story begins with the Giant's absence. Not only has he been away from his garden for several years, he has spent these years in Cornwall. Although Wilde gives no indication that the Giant's garden is located in Ireland or a place analogous to his country of origin, it is nonetheless important that the Giant is like an absentee landlord whose return from England destroys the paradisiacal harmony that emerged during his absence.
In addition, Wilde makes it evident that the Giant's occupation of the land takes away much of its value. He is blind to the fact that his garden thrives when the children play in it. As soon as he expels the children, the forces of winter take over and render the garden barren—just as many Irish people at the time saw their own lands as barren when owned by faraway landlords.
The poor children had now nowhere to play. They tried to play on the road, but the road was very dusty and full of hard stones, and they did not like it. They used to wander round the high wall when their lessons were over, and talk about the beautiful garden inside.
When the Giant evicts the children from his garden, they end up on the road with nowhere to go. They are shut out of what is essentially their own territory. The makeshift quality of the road as a setting underlines the fact that the children have been displaced and pushed into a less appealing environment. This may shed light on why the children end up going back to the garden despite their fear of the Giant, as it suggests that they're unwilling to simply give up the land with which they've become so intimately acquainted. In this way, the story serves as an allegory for the persistence that the Irish people showed while fighting for independence.
"The Selfish Giant" is an allegory that emphasizes the personal and collective importance of Christian love. Wilde suggests that all humans are the Giant. However, he also suggests that with the Gospel (or some other means of salvation) we can achieve not just happiness in life but eternal happiness. In the story, the reward for Christian love is an invitation to Paradise—by opening up his own garden to the children, the Giant is allowed into God's everlasting garden.
The story's didactic implications are well suited to the fairytale genre. Wilde's simple and straightforward narrative spells out the idea that selfishness is a sin that will be punished. The punishment of the Giant is also linked to the story's genre, as it is the various anthropomorphized elements of nature that eventually push him to recognize the consequences of his selfishness:
"I cannot understand why the Spring is so late in coming," said the Selfish Giant, as he sat at the window and looked out at his cold white garden; "I hope there will be a change in the weather."
But the Spring never came, nor the Summer. The Autumn gave golden fruit to every garden, but the Giant's garden she gave none. "He is too selfish," she said.
The response of the garden and the seasons to the Giant underpins Wilde's allegorical message. Spring, Summer, Autumn and their respective flora boycott the Giant's garden until he stops being selfish. Once he has repented and proven his willingness to change his ways, he is rewarded with the happiness that comes from the return of these seasons. Additionally, the clear correlation between the Giant's behavior and the behavior of the seasons allows Wilde to further reinforce the omnipresence of God in the world. An individual's selfishness would not normally affect the natural world, but in Wilde's Christian allegory, the two are intricately linked.
When the Giant reaches old age, he is further rewarded by being granted entry into heaven by the little boy, who represents Christ. Archetypal fairytale villains are rarely given a second chance, but in Wilde's allegory there is ample room for forgiving and redeeming a sinner. In fact, the reward for repenting ends up far outweighing the initial punishment. Wilde uses this narrative to emphasize the necessity of Christian love for the wellbeing of individuals and communities.