Hi Sol
If u are talking about vegetables then winter is HK's growing season.HK's summer is too hot and humid for most leafy greens and is suitable only really for the melon family(squashes/cucumber etc),chilli/capsicum,beans,gourds,water spinach.
Allow me to give a short guide on what to plant in winter (although we are somewhat late in the season now,late autumn being the sowing time ideally)
Winter
Beetroot,brussel sprouts,broccoli,cabbage,capsicum,carrot,cauliflower,chinese cabbage,kai lan,lettuce,radish,spinach,spring onion swede,sweet corn,tomato,turnip,white radish,marrow,most common herbs.
Depending on your garden ,soil ,shade etc(the micro climate) you can learn that seasons will overlap quite alot for certain things.I have just given anything a go over the years and always check for what the old timers are growing on their fields as a general guide.
If u were talking about trees,shrubs,flowering plants(decorative plants) then a large book would not be even enough to elaborate .I would say just give it all a go ,seeds are fairly cheap!
You might be interested to check the following website and consider linking up with some of the folk at
www.gardeninghonkong.com.
Another great resource for english speakers is a book called "Urban gardening for Hong Kong" by Arthur van Langenberg.
Unfortunatly the best knowledge is with the old locals who depended on the land for survival ,this however is being lost forever because the majority of HK younger generation haven't a chance to have a clue about the land(understandably) and wouldn't wanna involve in such "lowly" pursuits.
Hope this might help u a little .
Peace
JJ