STEINER'S PROPOSITION:
'...The stinging nettle is the greatest benefactor of plant growth, it can hardly be replaced by any other plant. It contains sulfur which plays an important part in assimilating and incorporating the spiritual. It also carries the radiations and currents of potash and calcium, but in addition, it has a kind of iron radiation that is nearly as beneficial for the whole course of nature as the iron radiations in our blood are for us... It should actually grow all around our hearts, since the role it plays in nature by virtue of its marvellous inner structure and way of working is very similar to that of the heart in human organism... Nettles like iron so much that they draw it out of the soil and into themselves... The remarkable thing is that we find the very opposite in the leaves of certain plants. If, for instance, we prepare the leaf of urtica dioica, the ordinary stinging nettle, in the right way, we have a remedy composed of sulphur, iron, and certain salts...
ESOTERIC COMMENT:
The nettle is a Mars plant. It aggressively stings when one comes too close. Is promotes the iron-Mars process, regulating iron economy in nature and bring active iron radiation to the soil. Mars, being the first of the outer planets, brings iron, magnesium, sulphur and other minerals. 504 can help to break up unhealthy iron soil conditions. The strength of the sting gives an indication of how strong the 504 will become. 
ABOUT THE PLANT:
Perennial plant with heart-shaped leaves that have fine-toothed edges and taper to a point. Dark, erect stems can grow as tall as three feet in height with alternating leaves. About midsummer tiny groups of reddish to green flowers cluster on tiny spikes. These flowers are incomplete with the male, or barren flowers, having only stamens. The female, or fertile flowers, only have the pistil or seed-producing part. While sometimes both flowers can be found on one plant it is more usual for a plant to have either a male part or a female part, which explains the 'dioica' part of its name meaning 'two houses'.
Properties: Cooling energy, drying, astringent. The aerial parts may be used as an astringent, diuretic, expectorant, haemostatic (stop bleeding), circulatory stimulant, nutritive tonic, improve milk flow for nursing, lower blood sugar levels, treat gout and arthritis, and prevent scurvy. The combination of iron and vitamin C is useful in treating anemia, because the vitamin C improves iron absorption from the GI tract. When boiled, they have also been used as a green dye. The root is used in combination with other herbs such as saw palmetto and pygeum to relieve symptoms of BPH. It has also been used as a conditioner for dandruff and hair loss. When mixed with salt and boiled it produces a yellow dye. Nettles are also helpful in relieving the symptoms of hay fever and other allergic reactions that produce increased congestion in the sinuses. The mineral content makes nettles helpful for goiter, osteoporosis, muscle cramps, high blood pressure and malabsorption syndrome. Almost any condition that requires improved mineral balance will benefit from nettles.
PRACTICAL FARMING CONSIDERATIONS:
The plants need to be harvested just before they flower. The whole plant is dried und stored until autumn in an unglazed earthenware pot. Bury the pot in healthy soil and leave it for a whole year, until the following autumn. 
Burying in peatmoss is also possible. After lifting the remains can be sieved and stored.
HOW TO APPLY 504:
Bind the preparation in compost or dry grass and drill deep holes into the compost heap. Insert the preparation into these holes and backfill.
Liquid manure: 
Wrap the flowers in cheesecloth or dried grass and tie them in such a way that they float on top of the liquid manure.