I agree here and it's almost exactly what I was thinking. Separation comes at the harvest, which comes a little later. The field and the crop are still maturing into wheat and tares. In Revelation 14 two angels come out and harvest:

The Harvest of the Earth

14And I looked, and behold a white cloud, and upon the cloud one sat like unto the Son of man, having on his head a golden crown, and in his hand a sharp sickle. 15And another angel came out of the temple, crying with a loud voice to him that sat on the cloud, Thrust in thy sickle, and reap: for the time is come for thee to reap; for the harvest of the earth is ripe. 16And he that sat on the cloud thrust in his sickle on the earth; and the earth was reaped.

17And another angel came out of the temple which is in heaven, he also having a sharp sickle. 18And another angel came out from the altar, which had power over fire; and cried with a loud cry to him that had the sharp sickle, saying, Thrust in thy sharp sickle, and gather the clusters of the vine of the earth; for her grapes are fully ripe. 19And the angel thrust in his sickle into the earth, and gathered the vine of the earth, and cast it into the great winepress of the wrath of God. 20And the winepress was trodden without the city, and blood came out of the winepress, even unto the horse bridles, by the space of a thousand and six hundred furlongs.