Posted: 12/01/2016 at 18:18
I've started garlic both earlier and later than this in previous years with similar good results, although ideally it would have been earlier.
January is usually the coldest month, so plenty of time for the garlic to get sufficiently chilled if you get it in urgently now, before we get to normal early spring growth. As you will read elsewhere, the cold helps the garlic cloves split and will contribute to larger bulbs.
No problem growing in large tubs or troughs, with a soil/compost mix maybe, which won't dry out as quickly as just compost.
Onion family are not heavy feeders, so don't over do it, or that could be contributing to more green growth above ground and smaller bulbs.
Onion family also prefer more neutral pH, so if you need to do any watering, use tap water, not rain water.