The theory of lunar planting is that the moon exerts a gravitational pull on the earth’s water table, which is highest during the full moon and lowest during the new moon. One obvious example is the rise and fall of tides, but - importantly for gardeners - it also affects the water table under the soil. During the first half of the lunar month, as the moon grows from new to full (ie a thin crescent to a round), its gravitational pull upon the ground beneath the gardener’s feet increases.
During the lunar month’s second half, as the moon dies (i.e. from round back to thin crescent), its gravitational pull decreases. This unfailing (roughly 4 weekly) phenomenon creates predictable conditions in the garden’s soil. From new moon to full moon (the first half), the moisture in Earth’s crust moves upwards under pressure from the rising water table, so there is an increased amount in the top soil.
This benefits the seed sown and the plant inserted at that time. Also, the same upward pressure encourages enhanced moisture absorption by seed and plant so the chances of germination and plant survival are increased. From full moon to the next new moon (the second half), the pressure upon root systems exerted by the prevailing moisture reduces as the water table falls. It is the ideal time to prune, because the reduced pressure causes reduced bleeding of cut branches; and to incorporate manure (and other feed) into the top soil, because the decreasing gravitational pull encourages additives to be more deeply absorbed; and to harvest root vegetable, when their moisture content is at their lowest so they store longer.
Before modem methods of farming were introduced after WW2, farmers apparently used the phases of the moon as a major indicator of when to sow. It is still used by at least one head gardener with 40 years experience — R. J. Harris on Tresillian estate Cornwall — with great success. He never needs to water his crops, though it is fair to say that he achieves this, not only using lunar planting, but also extremely thorough preparation of the soil in his veg beds in the preceding Autumn (he has a four year rotation plan and the first year involves massive excavation of soil and replacement with twiggy material, kitchen waste and well rotted manure in layers — and he aims to have the bed slightly lower than the surrounding soil when the mixture has decomposed, so rainwater drains into it). www.moongardening.cwc.net gives further information, dates of the moon’s phases and details of how to buy the book: R.J. Harris’s Moon Gardening: Vegetables and Soft Fruit.
