When to sow seeds?

Being generally befuddled by the range of contradictory advice on when to stick seeds in the ground, I was interested to see an article on moon growing in this month's Grow It magazine.

The editor's comment also rang true - "The date of the last frost, summer rainfall expectations and the strength of prevailing winds meld into the tapestry of influences that dictate what we grown and when we grow it. So the idea of adding another factor into the mix isn't instantly appealing." On the other hand, faced with different advice from different sources, maybe another factor could be the deciding one.

I'd heard of gardening by the moon before and been intrigued by it. It sounds rather like New Age mumbo jumbo, but the moon clearly does influence water levels here on earth, in the form of tides, so it's plausible that it could influence plants too. The article reported on a year's experiements conducted by the author, comparing a vegetable bed in which all the activities (digging, composting, sowing, harvesting, etc.) were carried out on appropriate days, according to the moon calendar, with a similar bed in which the same activities were carried out on what should have been exactly the wrong days. The results were impressive, at least for peas, beans and potatoes. As peas and potatoes are two of my main crops this year, this is good enough for me.

Naturally wanting to avoid spending money, I looked online for free information and found the reassuringly mainstream-looking Gardeners Calendar. Rather than reducing my confusion, this increased it by having three different systems; synodic (phases of the moon), biodynamic (zodiac signs, following Rudolf Steiner), and siderial (more zodiac signs, but different recommendations). The website firmly refrains from recommending one system over the other (or indeed moon gardening at all) but suggests starting with the synodic system whilst learning more about the others. This seemed like good advice, but I was bothered by the contradictions between the three, so started my learning with a visit to Wikipedia.

Overcoming my natural suspicion of anything involving zodiac signs, I looked up Biodynamic agriculture The article is very informative, but not hugely encouraging. For example,

Weeds are combated (besides the usual mechanical methods) by collecting seeds from the weeds and burning them above a wooden flame that was kindled by the weeds. The ashes from the seeds are then spread on the fields, then lightly sprayed with the clear urine of a sterile cow (the urine should be exposed to the full moon for six hours), this is intended to block the influence from the full moon on the particular weed and make it infertile.

This stuff is witchcraft! Apologies to any Wiccans, but really, this sounds like the kind of nonsense that gives witches a bad name.

So much for the biodynamic system (and because of its similarity, the siderial system, too). What did the author of the Grow It article use? She refers to a book called In Tune with the Moon, which a little research reveals she also wrote*. Rather irritating that she failed to mention this in her article, but ho hum. It doesn't undermine her results, if she reported them honestly, and why should I mind that she's an expert on the subject, rather than a merely an interested gardener?

*Edit - she's not the author, she's the marketing manager for the publisher. That makes me even less keen on her.

Links from the In Tune with the Moon webpage to pages on Biodynamic growing raise suspicions. I don't want any of this wacky nonsense, I want the kind with empirical evidence! Oh, hang on, they're the same thing. Am I a scientist, open to whatever the evidence says, or a dogmatist, who simply refuses to believe that exposing the urine of a sterile cow to the light of the full moon is going to have any effect on the ground elder?

I really don't know what to think. In addition to considerations of rain, frost, etc., I now have several guides to planting based on the position of the moon, some of which come with a hefty side helping of hocus pocus. I'm more confused than ever!