Lime Tree- leaves dropping off

I have a tahitian lime tree which is dropping off all it leaves, it is 3-4 feet tall and had lots of leaves when I bought it couple of months ago, is it common for this to happen because of the cold spell we have been having in melbourne or is there something else wrong, I have been putting seasol on it on a bi-weekly basis but no change. any thing else I can do to make it better. the tree is north facing, gets sun for 3/4 of the day.

Just wait till it warms up I guess. Is it in a pot? If it is it may not have adequate drainage. Either way it is stressed. Too cold, or too much water that isn't draining away. It will improve and seasol is wonderful to help. I would look too spraying the seasol on the leaves at this time of year as in the cold the bloody things just won't soak up anything we put on them be it fertiliser or much else. They will take things in through the leaves though and that is why we spray the foliage with zinc and manganese (Manutec do one) in winter along with regular doses of molasses diluted in water, again spray on the foliage is going do wonders but it is fine in the soil too