Hosta's might be a good choice in your situation, if they weren't exposed to the midday sun.
I planted a Hosta garden this year on one side of our house, air conditioning compressor unit is in the middle of this garden. They only get late afternoon sun.
Hosta's do incredibly well here in St Louis, MO when they're not planted out in full sun (or exposed to the midday sun).
- Cold winters, will drop below 0°F (-18°C).
- Hot, humid summers, today was 101°F (38°C), but felt like 113°F (45°C).
2011-06-16, Hosta has been in front of air conditioning compressor unit for over 2 years now (10 additional Hostas where planted this year to turn this "dead" area into a Hosta garden)
During my daily walk, I've noticed a lot of people screen (hide) their air conditioning compressor units behind:
I know you can get specific varieties of the above plants that are suitable, will do well in containers (pots). Of course around here, Canna lily and Elephant ear do not provide screening during the Winter months...
Listening to podcast, "Sunday August 28 2011 hour 2" from "Gardening Naturally with John Dromgoole", starting at 20mins:23secs John recommends a few plants to "hide" an air conditioning compressor unit, he highly recommend:
Today (2011-09-02), while waiting at the school bus-stop (for Alpha son) I noticed the nearby apartments screened their bank of conditioning compressor units behind:
You can get "Dwarf" varieties, I have one in my front garden, screening an above ground utility cover:
2010-11-10, Dwarf Burning Bush
2011-04-30, Dwarf Burning Bush
Now that it's their flowering season (late Summer, early Autumn/Fall), I'm really noticing a lot of "Stonecrops" around here:
Personally I like the look of the flowers, plus the ones listed above (and others, like Hylotelephium telephium 'Blackjack') have good looking foliage, at least I think their foliage is attractive. I'm thinking I might put one in garden...
After thought: From what I can remember and know of Hong Kong weather, isn't high levels of salt in the air another factor that needs to be taken into account when choosing suitable plants?