Gardening in China

Temps from -10 to 100°C??!! Do you mean °F?

And you can grow anything from seed anywhere given the right conditions for germination - it's what happens to the seedlings after that you need to worry about.

I would hope that you get replies from those used to growing under such conditions, usually experienced in central continental land masses around 40° or so north or south of the equator. I guess you are looking at plants suitable for growing in USA zones 5 or 6, or the northern/semi-mountainous areas of southern European countries.

Not sure what the air pollution will do. What is it - mainly sulphur dioxide? It may cause problems, but every cloud has a silver lining - it will cut out a lot of fungal problems! In the UK, before the Clean Air Act became law, it wasn't difficult to grow roses as the sulphur dioxide made life very difficult for rust and mildew! But after the air was cleaned up, the roses suffered.

Well gardening in China is good thinking but not always. In China some spots are where the population rate is very high so it leave a bad effect on gardening.