The New John Gill Exposition of the Entire BibleDeuteronomy 16:13
Thou shalt observe the feast of tabernacles seven days…
Which began on the fifteenth day of Tisri, or September; see (Leviticus 23:34) ,
after that thou hast gathered in thy corn and thy wine;
sometimes called the feast of ingathering, (Exodus 23:16) , barley harvest
began at the passover, and wheat harvest at Pentecost; and before the
feast of tabernacles began, the vintage and the gathering of the olives
were over, as well as all other summer fruits were got in.