From our garlic page
• Garlic grows best in hot wet conditions, but try it all year round. (I have only tried in the spring digging up in the summer, but am told that it can grow all year round.
• Ensure that the growing area is weed free.
• Garlic likes water, so if you live in a hot climate you may need to water it a fair amount. Just don't let it dry out is the common sense approach.
• After about four months you should have some lovely strong garlic, you can tell it is ready when the foliage dies down
• Dig up with a fork to avoid damaging the bulbs..
• Does best when the soil pH is in the 6.2 to 6.8 range.
It might be ready, I am thinking that as it has had over 4 months to grow then it could be, although it has been pretty cold - mind you it is hotter over there, so worth picking one out and seeing.