“in summer” or “in the summer”: which one is correct?

Alan is British, so there might be some difference between British and American usage. In American usage it’s safe to always use in the summer. I don’t know of any grammatical reason for saying in the summer. That’s just how people say it.

I’m not implying that there is anything wrong with saying, “In summer we enjoy the benefits a garden has to offer.” What I’m saying is that you can’t make a mistake if you always use in the summer.

When used as an adjective, you would not use the word ‘the’. For example summer weather, summer temperatures, spring morning, winter snow.

We only go swimming in the summer.
We only go swimming in summer weather.