Iron bars and iron fence - literal or metaphorical?

Question

This passage from The Children's Bach by Helen Garner:

‘At night, because of the noise of people laughing, they turned up the treble on the jukebox. But in the early mornings, in the peaceful shift when customers on their way to work were reading the papers, you could clearly hear the trip and run of the bass lines. Some people came alone, with a library book, dressed in clean clothes of sober cut and colour. Others brought their children and taught them, with smiles and soft words, how to behave in a public place. The clever children read aloud to their parents from the Situations Vacant, the Houses to Let. The big windows of the cafe faced east. People sat with their backs to the sun, and the iron bars of night softened in their shoulders. On the other side of the road, which sparkled with passing cars, a deep garden overflowed its iron fence.’

Does "and the iron bars of night softened in their shoulders" means: Iron bars of window that were cold at night now because of the sun light were warm and customers felts its warm in their shoulder? (This sentence was really unclear to me.)

And does "a deep garden overflowed its iron fence" means: A fence of a deep garden was damaged? (I have never heard "deep garden" Does it mean: A garden like an valley?)

Answer 1

The "iron bars" is metaphorical -- after night, their backs were stiff as if they had iron bars in them, but the morning eased them. The windows need not have iron bars, and if they had, they would not have softened in light.

On the other hand, the garden is "deep" because it is compared to a flood, "overflowing" its literal iron fence -- by having plants grow through. This would engulf but probably not push over the fence. (It doesn't tell what the plants are, but I would expect unspecified plants in a garden to be flowers, though I would not be too surprised at trees or bushes.)