James Halliday has never been busier, though he admits his commitments have made him a bit grumpy.

Every year, the former lawyer and winemaker churns out 'Australian Wine Companion,' his ever-expanding guide to wines in the region. The 2012 edition is his biggest yet: At 776 pages, it contains tasting notes for more than 6,000 wines and profiles of more than 1,000 wineries. A favorite among oenophiles, the book is the best-selling wine guide in Australia.

This year, in what he calls 'a moment of madness,' he agreed to write a second guide called '1001 Wines Under $20.' The book is slated to come out in November.

'I thought, 'Well, it's only 1,000 wines, I'll do that very quickly,' he says. 'It turns out it was murder.'

Mr. Halliday spoke with the Journal's Jason Chow about his new 2012 guide, the state of the Australian wine market, and how Australia can capitalize on the growing Chinese audience. The following interview has been edited.

The Wall Street Journal: What's your process for updating the guide?

James Halliday: I start my tastings in early June, but my peak tasting period is in early September. For 12 to 14 days, I'll be tasting every day from 7 a.m. to 7 p.m., two breaks during the day, for an annual Top 100 wines that I write for the Weekend Australian newspaper. I'll have tasted 1,200 to 1,400 wines for that. I taste 120 wines a day for 14 days. All wineries in Australia are invited to submit. The bulk of the wine notes comes from this.

My other source of tasting notes is from wine judging, mostly at regional wine shows. I deliberately judge smaller regional shows, because I pick up on small wineries that won't surface at capital-city wine shows.

The real ugly time for us is from January to late March, where we send emails to every winery in Australia to update their information. Winemakers come and go, and we have to update our database.

WSJ: What has changed the most about Australia's wine scene over the years?

Mr. Halliday: Back in our 2000 guide, there were only 1,000 wineries. Today, there's 2,400 active wineries. The industry has grown almost 1.5 times in the past 11 years. Even in this edition, we've added 105 new wineries.

WSJ: In Australia, there's still a massive wine glut and yet more wineries are still popping up. Tell us your take on the local industry today.

Mr. Halliday: It's paradoxical, isn't it? But the wine lake [the excess wine produced] is a byproduct of the dramatic increase of the wine industry, due to exporters, not those who were producing for domestic consumption.

Back in 1995, I was on a thinktank panel that did a 30-year vision for the wine industry, and we predicted that in 2025, we'd see the industry become a 4.5 billion Australian dollar (US$4.5 billion) industry with A$2.5 billion in exports and A$2 billion in domestic sales. But in fact, we hit those numbers in 2002. What we projected to happen in 30 years actually occurred in seven years.

Then in 2004, 2005 and 2006, we had three vintages that were all very good vintages