What is a reason the new england and middle colonies had fewer slaves than the southern colonies

There was more slaves in the southern colonies than in the Middle colonies and New England because they didn't think it was right to have slaves and they had mostly everything that they needed and could do it by themselves. 
And also the economy in the southern colonies was based on plantation farming. Plantations required large numbers of workers, so wealthy landowners bought lots of slaves. In the northern colonies, the geography and climate weren't favorable for large-scale farming. Up north, there wasn't as much good farmland, and the growing season was shorter. Northern farmers didn't tend to have nearly as much land to work, so they didn't need as many workers.