It usually takes very little to persuade me that daytime is the best time to taste wine - our palates are always fresher in the morning than in the afternoon or evening - but Marlborough winemaker Sam Weaver had another reason to draw wine writers together on this year's mid-winter solstice. It was a root day.

If you've even heard of a plant root day, you'll probably also know it's a regular feature on the biodynamic calendar, which Weaver adheres to - more or less. He follows "the more logical aspects" of biodynamics; the most extreme form of organics. Biodynamics was founded by Rudolph Steiner, whose ideas waver from easy-to-understand to downright kooky.

Today we're tasting Weaver's new wines on a root day rather than a flower day, leaf day or fruit day, all of which are on the biodynamic calendar. They are based on lunar cycles, which dictate the best days for the development of parts of the plant. Weaver finds root days to be consistently good for wine tasting.

Our tastebuds are dull when we're tired, stressed or having an off-day, but followers of biodynamics see a clearer pattern than mere bad days.

The British supermarket chains Tesco and Marks & Spencer have been using the biodynamic calendar to decide which days to taste wine on for the past few years. It's still early days, but their tasters have gone from cynics to biodynamic believers.

Jo Ahearne, of Marks & Spencers, said she was absolutely amazed by the consistent differences she saw between tastings held on root days and those held on flower days.

The book When Wine Tastes Best, by Maria and Matthias Thun, explains how the biodynamic calendar is based on the lunar and solar cycles, star constellations and planetary movements.

Back on Earth, on this root day, I'm tasting three of Weaver's pinot noirs. For me, the wine with the X-factor is Abyss Pinot Noir and is hard to find, being made in very small quantities. It's named because the grapes grow on vines which edge out to an abyss, overlooking the Omaka Valley in Marlborough. Root day or not, the 2008 Churton Abyss Pinot Noir tastes extremely good just after midday.

Wines of the week
2008 Churton Marlborough Pinot Noir $44
Winemaker Sam Weaver aims to pick his grapes on fruit and flower days on the biodynamic calendar because, he believes, they are optimal for top tasting wine.

This elegantly structured, savoury flavoured pinot noir is the result of that approach.

2008 Murdoch James Blue Rock Pinot Noir $26
Here's liquid proof that price needn't determine quality. Of two very differently priced pinot noirs this silky smooth velvet version beat the far more expensive wine. Smooth, spicy, lingering finish.

2009 Brown Brothers Cienna $16
And now to something less serious - Cienna was a sell-out when first made five years ago as a trial wine. Its low alcohol (6.5 per cent), light fizzy style and sweetness make it the perfect vinous rival for RTDs. The Cienna grape is a cross between cabernet sauvignon and Sumoll. At supermarkets.