Grape vines are shrubs and just like the fig tree their ability to produce fruit extend over several seasons of harvest.

The harvesting of firstfruits began the day after Passover* (Nisan 16) and lasted for 49 days (7 weeks) to Sivan 5 and culminated with the harvest Sabbath of Pentecost (Sivan 6).

Leviticus 23:10 Speak unto the children of Israel, and say unto them, When ye be come into the land which I give unto you, and shall reap the harvest thereof, then ye shall bring a sheaf of the firstfruits of your harvest unto the priest:

*Passover was on the 14th of Nisan and Feast of Unleaven Bread (also Passover) was on 15th of Nisan. Nisan 16 to Sivan 5 is 49 days. Sivan 6 was Pentecost.