Why was agriculture more successful in the middle colonies than in the north apex?

Because more land could be farmed, is the right answer.

Explanation:

The Middle Colonies, which incorporated New York, Pennsylvania, Delaware and New Jersey were the most prosperous settlements in terms of raising crops. These colonies not only produced food for themselves but for Europeans colonists. Due to more cultivable land, fertile soil and favorable climatic conditions agriculture were more successful in the Middle Colonies than the North.

Climate, plants are more reluctant to grow in colder climates. than in warmer ones.