These passages from the Bible show the association of the health of the fig tree with the spiritual health of the nation of Israel.

Thereupon this word of the LORD came to me: Thus says the LORD, the God of Israel: Like these good figs, even so will I regard with favor Judah’s exiles whom I sent away from this place into the land of the Chaldeans. I will look after them for their good, and bring them back to this land, to build them up, not to tear them down; to plant them, not to pluck them out. I will give them a heart with which to understand that I am the LORD. They shall be my people and I will be their God, for they shall return to me with their whole heart. And like the figs that are bad, ... will I treat Zedekiah, king of Judah, and his princes, the remnant of Jerusalem remaining in this land and those who have settled in the land of Egypt.

Like grapes in the desert, I found Israel; Like the first fruits of the fig tree in its prime, I considered your fathers. ...

I will lay waste her vines and fig trees, of which she said, “These are the hire my lovers have given me”; I will turn them into rank growth and wild beasts shall devour them.

On that day, says the LORD, She shall call me “My husband,” and never again “My baal.” Then will I remove from her mouth the names of the Baals, so that they shall no longer be invoked.

And he told them this parable: “There once was a person who had a fig tree planted in his orchard, and when he came in search of fruit on it but found none, he said to the gardener, ‘For three years now I have come in search of fruit on this fig tree but have found none. (So) cut it down. Why should it exhaust the soil?’ He said to him in reply, ‘Sir, leave it for this year also, and I shall cultivate the ground around it and fertilize it; it may bear fruit in the future. If not you can cut it down.’”

Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how many times I yearned to gather your children together as a hen gathers her brood under her wings, but you were unwilling!

The following is an excerpt is from the Apocalypse of Peter, a non-canonical book from "The Apocryphal New Testament".

And I, Peter answered and said unto him: Interpret unto me concerning the fig-tree, whereby we shall perceive it: for throughout all its days doth the fig-tree send forth shoots, and every year it bringeth forth its fruit for its master. What then meaneth the parable of the fig-tree? We know it not.

And the Master (Lord) answered and said unto me: Understandest thou that the fig-tree is the house of Israel? Even as a man that planted a fig-tree in his garden, and it brought forth no fruit. And he sought the fruit thereof many years and when he found it not, he said to the keeper of his garden: Root up this fig-tree that it make not our ground to be unfruitful. And the gardener said unto God: (Suffer us) to rid it of weeds and dig the ground round about it and water it. If then it bear not fruit, we will straightway remove its roots out of the garden and plant another in place of it. Hast thou not understood that the fig-tree is the house of Israel? Verily I say unto thee, when the twigs thereof have sprouted forth in the last days, then shall feigned Christs come and awake expectation saying: I am the Christ, that am now come into the world. And when they (Israel) shall perceive the wickedness of their deeds they shall turn away after them and deny him [whom our fathers did praise], even the first Christ whom they crucified and therein sinned a great sin. But this deceiver is not the Christ. [... the sense required is that Israel perceives the wickedness of antichrist and does not follow him.] And when they reject him he shall slay with the sword, and there shall be many martyrs. Then shall the twigs of the fig-tree, that is, the house of Israel, shoot forth: many shall become martyrs at his hand. Enoch and Elias shall be sent to teach them that this is the deceiver which must come into the world and do signs and wonders to deceive. And therefore shall they that die by his hand be martyrs, and shall be reckoned among the good and righteous martyrs who have pleased God in their life.

The next set of passages develop a picture of a time in the future when Israel, represented by the images of the fig tree and the cedar, will blossom and bear fruit that will benefit the whole world.

In days to come Jacob shall take root, Israel shall sprout and blossom, covering all the world with fruit.

I will be like the dew for Israel: he shall blossom like the lily; He shall strike root like the Lebanon cedar, and put forth his shoots. His splendor shall be like the olive tree and his fragrance like the Lebanon cedar. Again they shall dwell in his shade and raise grain; They shall blossom like the vine, and his fame shall be like the wine of Lebanon.

Therefore say: Thus says the Lord GOD: I, too, will take from the crest of the cedar, from its topmost branches tear off a tender shoot, And plant it on a high and lofty mountain; on the mountain heights of Israel I will plant it. It shall put forth branches and bear fruit, and become a majestic cedar. Birds of every kind shall dwell beneath it, every winged thing in the shade of its boughs.

The blossoming that will occur in Israel, the congregation of the faithful, will be brought about by the outpouring of the Holy Spirit in the end times, the latter rain.

... I will make Jerusalem a bowl to stupefy all peoples round about. (Judah will be besieged, even Jerusalem.) On that day I will make Jerusalem a weighty stone for all peoples. All who attempt to lift it shall injure themselves badly, and all the nations of the earth shall be gathered against her.

On that day, the LORD will shield the inhabitants of Jerusalem, and the weakling among them shall be like David on that day, and the house of David godlike, like an angel of the LORD before them. On that day I will seek the destruction of all nations that come against Jerusalem. I will pour out on the house of David and on the inhabitants of Jerusalem a spirit of grace and petition; and they shall look on him whom they have thrust through, and they shall mourn for him as one mourns for an only son, and they shall grieve over him as one grieves over a first-born. On that day the mourning in Jerusalem shall be as great as the mourning of Hadadrimmon in the plain of Megiddo.