Praise be to Allah

Firstly: 

The pomegranate is one of the fruits of Paradise. Allah, may He be exalted, says (interpretation of the meaning):

“in them (both) will be fruits, and date- palms and pomegranates”

[ar-Rahmaan 55:68]. 

Ibn Katheer (may Allah have mercy on him) said: 

The date-palm and pomegranate are singled out for mention because of their superiority over other fruits. End quote. 

Tafseer Ibn Katheer (7/507) 

Secondly: 

It was narrated by Ibn ‘Adiyy in al-Kaamil (7/543), and via him by Ibn ‘Asaakir in Tareekh Dimashq (56/186), via Muhammad ibn al-Waleed: Abu ‘Aasim told us, from Ibn Jurayj, from Ibn ‘Ajlaan, from his father, from Ibn ‘Abbaas, who said: I heard the Messenger of Allah (blessings and peace of Allah be upon him) say: “There is not one of your pomegranates but it is pollinated with a grain from the pomegranates of Paradise.” 

Ibn ‘Adiyy quoted it in the biography of this Muhammad ibn al-Waleed, and said: He fabricates hadiths and narrates them as mawsool, he steals, and he tampers with isnaads and texts. I heard al-Husayn ibn Abi Ma‘shir say: Muhammad ibn al-Waleed ibn Abaan is a liar. End quote. 

Adh-Dhahabi also narrated this hadith, in his biography of him in al-Mizaan (4/59), as one of his false reports. 

It was also narrated by Ibn al-Jawzi in al-Mawdoo‘aat (2/285), via ‘Abd as-Salaam ibn ‘Ubayd ibn Abi Farwah: Abu ‘Aasim told us…

Concerning this ‘Abd as-Salaam, Ibn Hibbaan said: He used to steal hadiths and narrate fabricated reports. Al-Azdi said: His hadith is not to be written down. Ad-Daaraqutni said: He is nothing. 

Therefore this hadith is false and fabricated.

It should be known that the fruit of Paradise resembles the fruit of this world in name only; as for its reality, there is a great difference between the two, the extent of which is known only to Allah. 

Ibn Jareer at-Tabari (may Allah have mercy on him) narrated in his Tafseer (1/392), with a saheeh isnaad from Ibn ‘Abbaas (may Allah be pleased with him), that he said: Nothing in Paradise resembles anything in this world, except in name. According to another version: There is nothing in this world of that which is in Paradise, except names. 

And Allah knows best.