Hello buddies. I reckon you will be shocked to hear that the word "garden" has two dissimilar usages in English language. In simple terms, the use and meaning of "garden" in U.S. is different from its use in U.K. To make it less difficult for you to understand I give its definitions separately:
Garden(in England): The area of land next to a house, where there are flowers, grass and other plants and often a place for people to sit.
Garden(in America): A part of the area next to a house, which has plants and flowers in it.
In the end, by reading this very, very short article you will never wonder why Brits spend most of their time, esp summer time, sitting in the garden whereas Americans consider it an odd and strange thing to do . Simply, people in the U.S. use the word "yard" instead of "garden".