Cape Town - 100726 - Full Moon Pineneedles against the moon from Newlands Forest in Cape Town - Photo: Matthew Jordaan

London - For gardeners, spring is the time of year to be out sowing seeds and planting. Rain and sun make for perfect conditions.

But for some gardeners, there’s one last detail still to fall into place.

Standing in their gardens, staring at the night sky with trowels in one hand and almanacs in the other, they wait for a full moon - the perfect time to dig and sow.

These people are not members of some weird cult, but belong to a growing group of gardeners who decide to plant their vegetables and fruit based on the phases of the moon.

Variously called “moon gardeners”, “moon sowers” or “lunar phase gardeners”, they subscribe to the theory that the lunar cycle has a direct effect on the growth of plants.

Although it sounds wacky, moon gardeners maintain that not only is science on their side, but also that the results are plain to see.

According to the theory, plants that are sown in the few days before a full moon become stronger and more productive, and those sown as the moon is waning tend to be less so.

The moon gardeners claim that the gravitational force of the full moon affects the level of groundwater in the soil, just as it does the level of the oceans. With more water being drawn up into the soil during a full moon, any newly-sown seeds are boosted by the increased hydration.

Plants are also said to benefit from the bright light reflected from the sun by a full moon, with some believers claiming lunar changes cause distortions in the Earth’s magnetic field that can encourage or limit plant growth.

In addition, specific plants are also supposed to benefit from being sown when the moon passes through certain constellations.

For example, root crops such as turnips are said to do well when the moon is in so-called earth signs such as Taurus and Capricorn. Whereas leaf plants such as lettuce and cress do best when the moon is passing through water signs such as Pisces and Scorpio.

One adherent to moon gardening is Charles Dowding, the author of well-regarded gardening books such as Salad Leaves For All Seasons and Vegetable Course Book.

“I’ve been doing it for 30 years,” he says, “and although I am still puzzled by it, one can see the results.”

Last year, Dowding conducted several trials with plants alongside each other, and compared rates of growth and yield.

Half the seeds were sown two days before a full moon, when it was waxing, and the other half were sown two days after, when the moon was waning.

He found that the most striking results were with the carrots. When he pulled them up in June, he found that the “waxing carrots” weighed a total of 7.8kg, whereas those planted when the moon was waning weighed just 4.8kg - a significant difference.

However, other results were less spectacular and even suggested that the plants benefited from going in the ground after the full moon.

Last July, he sowed two batches of turnip seeds around the full moon, and the “waxing turnips” weighed in at 3.3kg, whereas the “waning turnips” came in at 3.5kg. Some potatoes also showed a similarly small variation with a bias towards the “waners”, which came in at 4.7kg compared to 4.3kg for the “waxers”.

Dowding also tried experimenting by planting during the appropriate zodiacal sign days. Half a bed of carrots was sown when the moon was in a water sign, and the other half planted during an earth sign, during which the carrots were supposed to grow better.

“Both grew well,” says Dowding, “but after we weighed up the final harvest, I found a 20 percent increase in the total yield of the carrots from the root day [before the full moon]”.

When Dowding experimented with planting dwarf French beans, he found the yield sown on their appropriate zodiacal day was nine percent greater than those planted on the “wrong” day.

Although Dowding admits that his experiments were not conducted under laboratory conditions, and acknowledges that plants are affected by many variables - one half of a bed can drain differently to the other - he appears to be a believer.

“It’s all about the different powers of the moon,” he says. “In the last two days before a full moon, the male power of the moon - the yang - is very strong. However, after the full moon, the power is more female - the yin - and things tend to rest more.”

That may sound like mumbo-jumbo to some, but Dowding says that following the moon’s phases can do no harm.

“As far as I’m concerned, it’s all part of the whole planting process,” he says. “Besides, if it helps you pay more attention to matters like soil conditions, then so much the better.”

The custom goes back thousands of years. For centuries, farmers have worked by the phases of the moon, following the simple belief that the moon governs moisture levels.

Pliny the Elder, the 1st century Roman naturalist, stated in his work, Natural History, that the moon ‘replenishes the Earth; when she approaches it, she fills all bodies, while, when she recedes, she empties them’.

Ancient Hawaiians believed that tubers (such as sweet potatoes) had to be planted on the third, fourth, fifth or sixth day of the new moon to ensure that the crops would grow upright and firm.

Additionally, medicinal plants were gathered only during La`aukkukah and La`aukulua, the third and fourth days following Hoku, the full moon.

Many modern followers of moon gardening say that scientific evidence is on their side, and point to research in the 1950s by Dr Frank Brown, of Northwestern University in the United States, who supposedly proved that plants absorbed more water around the time of the full moon, and also during a new moon.

Besides changes in groundwater levels, Dr Brown’s research suggested that some plants - such as potatoes and carrots - absorb a little more oxygen at the time of the new moon, possibly because of a tiny change in barometric pressure. However, the variances are so small, that most experts dismiss their importance. Some moon gardeners also point to a series of plant experiments in the 1930s that appeared to show that the “moon effect” did, in fact, work.

Some other advocates of moon planting, such as Julian Gower, the publisher of Gwydion’s Moon Planting Guide, suggest the bright light of a full moon means that plants can photosynthesise (the process of converting light energy to chemical energy) by night as well as during the day and, therefore, grow more.

However, this suggestion has been rejected since the only plants that can photosynthesise from moonlight are certain types of phytoplankton, which are not usually to be found in your average back garden.

One of those who has little time for moon gardening is Professor Stefan Buczacki, the former chairman of Gardeners’ Question Time on Radio 4.

“It’s baloney,” he says. “If there was anything seriously in it, why over the centuries has not every gardener or, more importantly, every horticulturalist, followed these maxims? Why is it that people who plant by the moon don’t win all the prizes at the shows, or develop all the new varieties?”

But despite the lack of any scientific backing for their ideas, the moon gardeners are adamant that moon planting works. As Charles Dowding says: “Why not give it a go?”

Even Professor Buczacki admits that it can do no harm: “I take the view that like so many of these things, if it works for you, then that’s great - you enjoy yourself and you do it.” - Daily Mail