Comma after location?

Solution 1:

It doesn't necessarily need a comma, but it helps separate the different parts of the sentence, making it easier to understand at first glance.

Comma use has some strict rules, but a lot of the time, comma usage depends on personal preference.

Solution 2:

Sometimes it is a good idea to add a comma to a sentence at a point where, if read aloud, you might want to have a small pause.

With your first example:

In the picture(,) you can see that the flowers were blooming.

If this was dialogue and the person was pointing the picture out to the audience then a pause whilst people focus on the picture might be helpful. However, if this text was on a web page with the picture shown above or below the text then you would not need this comma.

In the second two examples there is no justification for adding a comma. That said, if those examples were part of a longer sentence, then the commas could be useful. For example you could have:

Some people dispute that the city 'never sleeps'. However, at midnight, you can hear that a city is never quiet.

Although 'at midnight' is not an option clause therefore needing commas, once read aloud the extra pauses give the emphasis needed.