Throughout the OT, and in the NT, the fig tree as a symbol is tied in with expectation -- and withering is tied in with judgment (Jeremiah 8:13, Hosea 9:10, 16, Nahum 3:12, Luke 13:6-9).

Note as well that in the messianic age, fruitfulness was a sign of blessing (Revelation 22:2). Witherington adds that the fig tree was a special sign of fruitfulness for Israel. It was often the tree used to bring firstfruits to the Temple. The fig tree was an "emblem of peace and prosperity" and in the messianic age was thought to bear fruit.

These points serve to answer the question of why Jesus expected figs -- at a time of year (April; the normal season was much later) when there wouldn't be any normally. As he approached Jerusalem, his acceptance as Messiah would have ushered in the Messianic age.

Checking the fig tree for fruit out of season was a signal: Had he found fruit (which normally came in after the leaves), it would have been a sign of the coming Messianic Kingdom.

Since he did not find fruit, the tree became a symbol for fruitless Israel, and of his rejection, and was withered -- in line with the OT judgments prescribed above. The withering of the fig tree is an enacted parable (that recorded in Luke) and a prophetic demonstration.

To ask why Jesus was "irritated" or "peevish" is to miss the significance of this episode....and Mark is actually offering a double meaning when he says it was "not the season for figs." The "season" in question is not the normal fig season, but the "season" or time of the Messiah.

The Greek word Mark uses is also used in a highly symbolic way: Mark 1:15 And saying, The time is fulfilled, and the kingdom of God is at hand: repent ye, and believe the gospel; Mark 12:2 And at the season he sent to the husbandmen a servant, that he might receive from the husbandmen of the fruit of the vineyard.

There's another problem. There is chronological contradiction between recountings of "whether Jesus overthrew the tables of the money-changers (Matt. 21:12) and subsequently cursed the fig tree (Matt. 21:19), or cursed the fig tree (Mark 11:14) and then threw out the money-changers (Mark 11:15).

The correct solution recognizes the ancient historiographical practice of arranging material topically for didactic purposes, rather than following a strict chronology.

But Matthew's gospel has the fig tree withering "immediately" while Mark has the fig tree withering the next day.

Actually, if we want to be particular, that's not what Mark says. Mark says nothing about when the tree withered; he says that the next day Peter in particular noticed the withered tree.

And if we really want to get down to details, the word translated "immediately" (parachrema) is the same word used in Acts 16:33, where Paul's former guard was "immediately" baptized along with his family. So, the "clear" chronological marker has a degree of latitude.

More significantly, the amazement of the disciples over the withering of the tree takes place "[w]hen the disciples saw this..." which is certainly non-specific in terms of elapsed time, and might as well be the next day as recounted by Mark (in view of our lesson about dischronologized narrative).

Finally, the clincher on this is that Mark's narrative is clearly and unquestionably fit into an intercalation pattern used throughout his Gospel, so that at once any questions of chronology become academic when this pattern comes to the fore.