Organic pesticide from the kitchen: nettle against aphids

Organic pesticide from the kitchen: nettle against aphids

Formic acid against lice

The stinging hairs of the nettle make it possible. At its uppermost tip there is a kind of head that bursts open when touched and releases an acid it contains. It is formic acid. This acid kills aphids, but also spider mites and whiteflies.

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Make nettle liquid or nettle stock

In order to obtain a usable pesticide from the nettle, the plant should be made into a liquid manure or a brew. Both liquids are effective. However, the manure requires a little more patience and can, for. B. can also be used as an effective fertilizer if the amount is too large.

If the nettles are placed in water, the 'heads' with the poison also open. The formic acid is released into the water. In the case of liquid manure, the silica also dissolves from the leaves, which strengthens the cell walls of the plants and has a preventive effect against vermin.

Nettle manure: it takes 1 to 2 weeks

How to process the nettle into a liquid manure:

  • Harvest and chop stinging nettles
  • Put 1 kg of nettles in 10 liters of water
  • Wait 1 to 2 weeks
  • stir regularly
  • Manure is ready when no more bubbles form

Nettle broth: wait 12 to 24 hours

With the nettle broth or stock, only the soaking time or waiting time changes. If you prepare the brew in the evening, you can use it the next morning. In contrast to liquid manure, it is not fermented and less rich in nutrients.

How liquid manure / broth are used against the aphids

Those who see the success will probably refrain from fighting nettles in the future ...

  • Use undiluted liquid manure / broth
  • put in a spray bottle and spray plants
  • Broth can also be poured over it
  • Repeat application regularly
  • Check for renewed pest infestation


Never spray or water your plants with the nettle liquid in sunlight! The leaves could be damaged and burned, for example.