Stinging nettle tea | The most frequently used and arguably most effective plant-based spray used on Biodynamic vineyards is made from the shoots and leaves of stinging nettles. These can be picked in spring (Pierre Masson, 1998: p.112) or until mid-summer as for the stinging nettle compost preparation 504.

Why used | Stinging nettle’s multiple beneficial effects include increasing resistance to pests and diseases, aiding photosynthesis and stimulating growth by providing a long list of trace elements including iron, potassium, sodium, sulfur, calcium, chromium, selenium, silicon, cobalt, zinc, magnesium and manganese. Countless French Biodynamic wine-growers say stinging nettle alleviates chlorosis (leaf yellowing) caused when iron and manganese become blocked on alkaline soils.

Stinging nettle’s role in promoting sap flow in hot weather helps deter aphids like red spider mites which colonise parched leaves and vine wood. For this a cold nettle extract is sprayed in summer just before lunar apogee, a period during which the moon is said anyway to evoke a ‘summer mood’. The cold extract is made by following Thun’s recommendation of soaking fresh stinging nettles, which can be in flower but must not have gone to seed, in cold or lukewarm water for 24 hours. She says to spray it twice in a matter of a few hours but this is easier for small allotments than most vineyards (Maria Thun: 2003, p.130). Sattler & Wistinghausen (1992, p.78) suggest stinging nettle can be combined with horn silica 501 sprays.

As a soil spray stinging nettle suppresses the upward movement of fungal disease spores, especially in the days leading up to full moon (Andrew Lorand, 2005: p.121) or when the sidereal moon stands in the leaf/water constellations Scorpion, Fishes and Crab (Thun: 2003, p.175). In India, Proctor (2001) found that blending 5% fresh cow’s urine in nettle tea (made there from U parviflora rather than U dioica) is effective against chewing and sucking insects.

Courtney says that diluting the solid stinging nettle biodynamic compost preparation 504 in water produces a spray which when applied separately or used as a watering-in agent around plants strongly stimulates leaf growth, and can be of some benefit in preventing frost damage (Hugh Courtney: 1998).

Stinging nettle tea is often combined with copper and sulfur sprays to minimise the hardening effect copper has on vine leaves, meaning lower doses of it can be used, as long as the pH of the mixture is neutral or slightly acidic (Pierre Masson, 1998: p.121).

Note: Stinging nettle may act as a host plant for Hyalesthes obsoletus, an insect vector of an incurable vine wood disease, Bois noir.

Bibliography

Andrew Lorand., ‘Backyard Biodynamics’, Biodynamics 254/2005, p.21.

Sattler, Friedrich., and von Wistinghausen, Eckard., Bio-Dynamic Farming Practice (Bio-Dynamic Agricultural Association UK, 1992) trans. by A. Meuss, p.78.

Hugh Courtney., ‘The Michaelmas Preparation: BD#504 Stinging Nettle’, Applied Biodynamics 24/1998, p.7.

Hugh Courtney., ‘The Michaelmas Preparation: BD#504 Stinging Nettle’, Applied Biodynamics 24/1998, p.7.

Maria Thun., Results from the Sowing and Planting Calendar (Floris, 2003) trans. by G. Staudenmaier.

Monty Waldin., Biodynamic Gardening (Dorling Kindersley, 2015).

Monty Waldin., Biodynamic Wine (Infinite Ideas, 2016).

Peter Proctor., ‘Making liquid seaweed fertiliser’, in Biodynamic Perspectives, ed. G. Henderson (New Zealand Biodynamic Association, 2001), p.13.

Peter Proctor., ‘Making liquid seaweed fertiliser’, in Biodynamic Perspectives, ed. G. Henderson (New Zealand Biodynamic Association, 2001), p.13.