Whenever I think I know it all, I just do some Googling to become quickly humbled.
In this case, I found out that Equisetum arvense is used by biodynamic farmers to ameliorate the effects of too strong OR too weak moon forces. When used properly it attracts rain, provided that it is used in a water constellation; Cancer, Scorpio, or Pisces. On the other hand, it curbs excess water when used in the fire constellations; Aries, Leo, or Sagittarius. The result is that beneficial fungi grow better and detrimental fungi die out.
There is actually some scientific basis for this. Field Horsetail has a high concentration of silica, the same stuff that is in those little dry-packs that are sometimes put in packaging to absorb moisture. In this way if a bunch of horsetail is put in a field it could regulate the amount of moisture available to other plants. I don't know much about astrology, but that could be a timing sort of thing. All in all, this may work to improve your organic garden.
|The sterile stem branches upwards and has a separate stem that sticks up from the middle|