Ian, lIke many other gardeners, is unsure whether he should sow and transplant in the correct moon phase, or sow seeds by the moon phase and transplant anytime, or sow seeds anytime and transplant by the moon.
Over many years of experimenting with moon planting, we’ve found that it is more important to sow seed during the correct phase, than it is to plant out during the correct phase. Seedlings of some varieties of annuals are large enough for transplanting by the time the next correct phase comes around, so it is easy to sow and transplant in the same phase. Others varieties take a shorter, or longer, time to reach transplanting stage, and my advice is that these should be planted out when they are ready, and when climate conditions are suitable, whatever the moon phase. Seedlings sown in a tray will suffer some transplant shock because they often have to be teased apart for transplanting, and these will require some TLC until they become established. However, annual seedlings sown in segmented punnets or individual tubes suffer very little transplant shock and it does not seem to matter when they are transplanted because their root balls are buffered by surrounding mix.
Planting out during the correct phase is important for perennials as strong establishment of the root system is essential for vigorous growth of these plants. This group includes fruit trees and crowns of asparagus, artichokes, herbacous perennials, strawberries, etc., as well as all trees, shrubs and vines.
Most root crop annuals are best sown direct where they are to grow as many don’t perform well when transplanted. If you have to transplant these because mice or ants steal seeds sown in beds, and they are ready to transplant in an incorrect moon phase, just give them some extra TLC. Moon planting gives some extra help in getting plants growing, it is not essential to their survival.
Traditional moon planting is based on observations of farmers for many centuries but very little scientific research has been carried out on why, exactly, certain seeds germinate faster, and grow quickly when sown at particular times, and why cuttings form roots more quickly when taken during Full Moon phase. A brief coverage of this subject on a David Suzuki TV program some years ago stated that fluctuations in sap flow and plant hormones corresponded with the Moon’s gravitation pull, as did subtle variations in Earth’s electro-magnetic field. I think the changes in the electro-magnetic field might be the key to why moon planting works, as plants can only absorb nutrients as water soluble, electrically–charged particles. A serious scientific study of this subject would be most interesting.