Winemaker Jenny Dobson says she is scared. And given her tense manner at the head of the upstairs tasting table at Rocco on Ponsonby Rd, I believe her.

Dobson doesn't fear for her life but, like most winemakers at this time of year, she is concerned about the life of her grapes.

Instead of leading a tasting of her top red wine, Boundary, Dobson is keenly aware that she should be hot-footing it around her Hawkes Bay vineyards, checking out the flavours of her grapes so she can gauge exactly when to pick them.

The grapes and vineyards she works with don't belong to her, but Dobson's sense of ownership makes her one of New Zealand's best winemakers.

Her job is chief winemaker at Te Awa winery in Hawkes Bay. Te Awa, named after the Maori River of God, was established in 1992 by the Lawson family. They sold it at the end of 2002 to North American business partners Julian Robertson and the late Reg Oliver, who jointly bought the land, winery and Te Awa Winery restaurant.

Dobson joined wine writers in Auckland to taste the latest vintages of Boundary from 2002, 2001 and 2000, the company's flagship wine which was first made in 1995.

Instead of looking back at all eight vintages Dobson pulled out the last three because, in her words, they show an important style departure. The wine is a three-way blend, made mostly of merlot, with cabernets franc and sauvignon in the mix.

And now Dobson, the queen of red-wine blending in New Zealand, has tweaked the formula in these last three vintages to include more cabernet franc than before.

Cabernet franc was not in the 1995 wine but since then it has increased in importance. The 2002 Boundary contains 16 per cent cabernet franc, heralding a stylistic evolution that Dobson hopes to continue developing. She believes cabernet franc adds more consistently ripe aromas and flavours than cabernet sauvignon can deliver regularly.

In part, this is about climate and that cabernet franc tastes fruitier and richer than cabernet sauvignon at similar ripening dates. The change is also Dobson's personal preference.

She believes that if the blend of grapes in a wine is formulaic and tastes so disjointed that the grape mix in any wine is obvious, the blend should be either reworked or discarded.

As good as the latest Boundary is, it plays only a small part of Te Awa winery's total production. Conversely, one of the cash cows for Te Awa is sauvignon blanc, and Dobson's version is a blend of grapes that has been treated differently.

Half of the 2005 Te Awa Sauvignon Blanc was fermented in oak and tastes more of stone fruit than green plums and freshly cut grass, the signature taste of many Marlborough sauvignon blancs. Dobson believes this is as it should be.

She would never try to make a sauvignon blanc that tastes as if it was from Marlborough when she had used grapes grown in Hawkes Bay. Like her move towards cabernet franc in Boundary, Dobson plays to the strengths of the region she is working in.