Why do some wines taste differently on different days? For years professional tasters, including myself, have agreed that some days seem better for assessing wine than others. Followers of the biodynamic wine calendar, who deliberately hold their tastings on the most auspicious days of the lunar cycle, have a wacky but, they maintain, entirely reasonable explanation.

Ever since the Austrian scientist and philosopher Rudolf Steiner published his theories in l924, biodynamic producers have divided the year into fruit and flower days — the best for tending vines and flowers and for tasting, apparently — and leaf and root days — the worst for tasting, but best for tending leaf vegetables and for planting.

Marks & Spencer was the first big British retailer to hold its tastings on the most favourable fruit days four years ago, along with the small burgundy specialist Howard Ripley, but it took Tesco and Berry Bros & Rudd until last year to follow suit. This winter I suspect that few tastings will be organised without prior consultation of Maria and Matthias Thun’s 2009 Biodynamic Sowing and Planting Calendar, although Waitrose is a notable dissenter.

Attempting to prove that fruit days are fab and root days are foul, Marks & Spencer showed the same wines on two separate days this month and asked me to spot the difference. But despite drilling down through my tasting notes I could not agree that the fruit day wines were fruitier and more lifted, or that the wines on root days were duller, with more marked phenolics and aggressive tannins.

I did think, though, that anyone swigging the wondrous, damson plum fruit of the 2007 Baglio Rosso Nero d’Avola (£5.99), the fat, inky, spiced plum-like 2007 Les Orris Rouge, a £7.99 Vin de Pays des Côtes Catalanes, the Perrin brothers’ blackberry-charged burnt, burly 2007 Rasteau from the southern Rhône (£9.99) and Domaine Bunan’s bold, rich, earthy 2004 Bandol (£12.99) from southern France, would have a lovely time at those end-of-summer barbecues whatever the day of the week.

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