One of the more popular interpretations of this poem is that "The Garden" is about—gasp—gardens in seventeenth-century England, hence the title of the poem. Not surprisingly, there's a lot of support for this theory. The poem certainly talks a lot about flowers, trees, fruit, nature and other garden-y things, plus European gardens from the 1600s were usually very carefully landscaped, so the idea that Marvell's uniform stanzas and meter mirror the formal, symmetrical layout of the traditional seventeenth-century gardens isn't without some street cred (see the "Form and Meter" section for more).
But the poem isn't called "Gardens," "A Garden," or "The Garden at Whateverland Palace," it's called "The Garden," and when anyone from the seventeenth century is talking about the garden, it's usually the Garden of Eden they have in mind. This, too, makes a lot of sense because, once upon a time, lots of British people thought of England as being a lot like The Garden of Eden.
If that last sentence made no sense to you, let us catch you up real quick. Marvell's use of the term "garden-state" in line 57 (not a reference to the state of New Jersey's license plates) is our first clue that something's up, but there's historical context that really brings this England-as-Eden concept home. Before Marvell was alive, England was ruled by a charming lass named Queen Elizabeth. She did lots of things well, but one of the things she did best was make everyone in England believe that England was awesome, something she accomplished (in part) by emphasizing the fact that God had a special, super-awesome destiny in store for the country. Being unofficially dubbed the promised land, plus the fact that England was green and filled with lots of flowers, was enough for many people in the late 1500s, so the idea of England-as-Eden was born.
By the time Marvell was writing, though, England has been through civil wars, international conflicts, plague, economic failure, and had killed a king only to reinstate his morally questionable brother; whatever Garden of Eden points Elizabeth I had racked up during her reign were obliterated and then some. So why was Marvell talking about England as some idealized garden paradise when it so clearly was not?
One thought is that Marvell is longing for a return to more peaceful times, both spiritually and politically. Another is that he is looking forward to England's bright future now that all the nastiness of the wars-sickness-death-starvation has been dealt with. Or perhaps the Garden of Eden references are meant to expose the decaying state of England, not its glorious past or future. A fourth theory is that the Bible has nothing to do with this poem at all and the speaker is just trying to talk about plain old regular gardens—no ifs, ands, or Biblical paradises about it. The English nerds have yet to agree on an answer, Shmoopsters, so we are officially giving you license to run with any of these theories that you like, or come up with one of your own.