Passage 4.17.11
τὸν δὲ χρόνον τῆς πολιορκίας γενέσθαι τοσοῦτον δηλοῖ καὶ τάδε ἔπη Ῥιανοῦ πεποιημένα ἐς τοὺς Λακεδαιμονίους· οὔρεος ἀργεννοῖο περὶ πτύχας ἐστρατόωντο χείματά τε ποίας τε δύω καὶ εἴκοσι πάσας· Rhianus, unknown location. χειμῶνας γὰρ καὶ θέρη κατέλεξε, πόας εἰπὼν τὸν χλωρὸν σῖτον ἢ ὀλίγον πρὸ ἀμητοῦ.
That the duration of the siege was indeed long is indicated also by the following verses composed by Rhianus concerning the Lacedaemonians: "Around the folds of the silvery mountain they campaigned for two and twenty seasons, winters and grass-times all together." For he counted winters and summers, calling "grass-times" the green corn or the crop slightly before harvest.