Along with the other prophets, Jeremiah loves a good vegetation metaphor (see our earlier comments on figs, e.g.). In the second chapter, God attacks Judah for being a domesticated vine that went rogue: "Yet I planted you as a choice vine, from the purest stock. How then did you turn degenerate and become a wild vine?" (2:21) So Judah has gone all "Attack of the Killer Tomatoes"—rebellious fruit (because tomatoes are technically a fruit) on a madcap binge of idolatry.
But some vegetation metaphors are positive. In Chapter 3:5-6, God states, "The days are surely coming, says the Lord, when I will raise up for David a righteous Branch, and he shall reign as king and deal wisely, and shall execute justice and righteousness in the land. In his days Judah will be saved and Israel will live in safety. And this is the name by which he will be called: 'The Lord is our righteousness.'" Whoever the "Branch" is he's going to be the savior of his people, whether you are interpreting the "Branch" as a Messiah yet to come, Jesus, Bahaullah, or anybody else.
When God shows Jeremiah an almond tree in blossom in 1:11-12, and says he's "watching over his word to perform it," the great Biblical commentator Rashi explains that this is because the almond tree blossoms before all other trees. Therefore God's word will be fulfilled before anything else comes to fruition (any of the schemes of humans.) (Source.)
All of these images compare human society to a something that must be cultivated in order to grow and flourish, like any plant in any garden. It must be carefully tended or else it's "Killer Tomatoes" all over again.