33 Hear another parable: There was a man that was a householder, who planted a vineyard, and set a wall around it, and digged a winepress in it, and built a tower, and let it out to husbandmen, and went into another country.
34 And when the season of the fruits drew near, he sent his servants to the husbandmen, to receive his fruits.
35 And the husbandmen took his servants, and beat one, and killed another, and stoned another.
36 Again, he sent other servants more than the first: and they did unto them in like manner.
37 But afterward he sent unto them his son, saying, They will reverence my son.
38 But the husbandmen, when they saw the son, said among themselves, This is the heir; come, let us kill him, and take his inheritance.
39 And they took him, and cast him forth out of the vineyard, and killed him.
40 When therefore the lord of the vineyard shall come, what will he do unto those husbandmen?
41 They say unto him, He will miserably destroy those miserable men, and will let out the vineyard unto other husbandmen, who shall render him the fruits in their seasons.
42 Jesus saith unto them, Did ye never read in the scriptures, The stone which the builders rejected, The same was made the head of the corner; This was from the Lord, And it is marvelous in our eyes?
43 Therefore say I unto you, The kingdom of God shall be taken away from you, and shall be given to a nation bringing forth the fruits thereof.

From the Book:  Peeps at Many Lands, The Holy Land, by John Finnemore, London, 1908

The grape harvest took place in Sept. and Oct.  As the grapes ripened there were thieves who tried to help themselves to the sweet fruits of the vine keeper's labors:  

"Watch must be kept for thieves, who climb the walls at night to steal the precious bunches, and watch must be kept for animals, which will do terrible mischief among the vines if once they break into the vineyard.

Wolves, bears, jackals, foxes, and the village dogs all are very fond of grapes and some of them are very nimble and not easy to keep out.  As the vintage time draws near, the keeper of the vineyard gathers a great store of thorn-bushes and lays them along the top of the walls.  The thorns project beyond the wall, and the bushes are weighted with stones to keep them in place.  This prevents animals from getting in and steeling the grapes.

The vineyard supplies fresh fruit, raisins, and wine.  The fresh grapes are eaten in great quantities during their season, the months of September and October, and still greater quantities are dried for the winter’s store.  In a warm, open spot in the vineyard a smooth floor is prepared, and here bunches of grapes are spread out to dry.  The bunches are frequently turned, and are sprinkled with olive oil to keep the skin moist.  If the weather is hot and dry the grapes become raisins about a fortnight, but unfavourable weather, cloudy or misty, prolongs the time required, and the raisins are not so well flavoured, and are of darker colour.  When the raisins are ready, the women store them carefully in the earthen bins, and they form a valuable part of the food-supply of the year." 

Photo of a Walled Field with a Watchtower at its Corner