Matthew 21:19-20 When Jesus cursed the figtree, it whithered away immediately.
Mark 11:14,19-21 The figtree was cursed by Jesus, and whithered away by the next morning.
This apparent contradiction is often used when someone tries "to prove" that the Bible is obviously full of contradictions because it cannot be that a figtree according to one record whithers away after some time, sort of like over night, and yet is supposed to have whithered away immediately according to another record. This indeed cannot be and this was not the case. Both gospel records are in themselves clear and they record that a figtree whithered away. Since it is impossible that this was one identical figtree, these records must be speaking of two different figtrees, i nother words we have records about two similar situations but not about one identical situation.
In orde to solve this apparent contradiciton it is necessary to carefully read the respective context of each of these sections and to pay special attention to which identical incidents and events are mentioned in both gospels from which one can recognize the chronological sequence and determine the point in time for the cursing and the whithering away of each figtree. In the study Anointing of Jesus and Entry into Jerusalem I have given information about the sequence of events which happened in those days and which are also of importance to the topic at hand in this study.
First of all we should notice that Jesus entered into Jerusalem on one colt (cp. John 12:12-19 & Mark 11:1-11); this happened on the day after his arrival in the area of Jerusalem and a meal at the house of Lazarus in Bethany (cp. John 12:1-11). After Jesus had gone into the temple on this day and had looked around on everything, he returned that evening again to Bethany. The entry into Jerusalem on one animal is recorded both in John 12 as well as Mark 11, and it serves as a point from which to calculate on.
On the next morning Jesus once again went to Jerusalem, this time his entry into Jerusalem was with two animals. On this day, Jesus again went into the temple, but this time he cleansed the temple and caused the money changers and merchants to leave the tmeple (cp. Mark 11:12-19 & Matthew 21:1-17). The cleansing of the temple which is recorded in both Mark 11 as well as Matthew 21 is the next fixpoint which helps set the time frame accurately. It was on this morning, before Jesus entered for the second time in a triumphant entry into Jerusalem that he passed a figtree on his way to Jerusalem, and that he looked at this figtree closer and that he finally curded it. The diciples were astonished seeing him speak to a tree but nothing much happened there and they went onward into Jerusalem, went into the temple, and after Jesus had taught in the temple on that day, they all left in the evening to depart from the city once again.
On the next morning, when Jesus with his disciples was once again on his way into the city of Jerusalem, they passed the place and the figtree which Jesus had cursed the day before, and they noticed that this tree had whithered away over night and had dried up from the roots (cp. Mark 11:19-21). Jesus used this opportunity to teach them about having faith in God. A short while after this, as they were coming close to the city itself, they passed another figtree, and Jesus once again went to this tree, looked at it, and he cursed it after he did not see any indication that this tree was going to bear any fruit. Now, this figtree whithered immediately, right on the spot, which greatly astonished the disciples. Jesus repeated his lesson on faith or believing, and they all went on their way into Jerusalem and wnet into the temple where Jesus was teaching for an extended period of time that day. After this, Jesus went with his disciples to the mount of Olives where he expounded to them some further details of those items he had taught that day. Nachdem Jesus seine Lektion über Glauben wiederholt hatte, gingen sie nach Jerusalem hinein zum Tempel, wo Jesus an jenem Tage
As we can see, the solution of this apparent contradiciton is found in recognizing that these records are not speaking of one identical figtree but rather of two different figtrees which were cursed at different times and which whithered away at different times and in a different manner.