How to prepare homemade nettle extract or porridge

the nettle porridge is a concentrate of plants of the genus urticaria which can be of great help in controlling different pests and diseases. In fact, in professional agriculture, nettle extract is classified as a basic substance to fight against mites, aphids and even to reduce the development of certain leaf diseases, such as powdery mildew.

Although the concentrations of urticaria achieved with the nettle porridge that we can make at home will be much lower than that obtained industrially, if we follow the steps in its preparation we will be able to obtain an interesting broth to apply to all our plants, including those that we have in pots.

With the term slurry we refer to the fermentation process What happens with the remains of plants of the genus urticaria, preferably from the nettle plant. With this natural process it is possible to obtain all the juice and concentrate of the plant.

Also count that there are more 19 species of urticaria spp. thus each manufacturer can choose a different composition according to the varieties chosen. However, the most common species is great nettle (Dioecious urtica) and small nettle (Urtica urens)

Composition of nettle extract

The insecticidal and fungicidal activity of nettle slurry is mainly due to the terpenes and the composition of its trichomes (stinging hairs).

The complete composition of nettle is as follows:

Sheets stinging hairs Domain Seeds
Chlorophyll Acetylcholine Tannins mucilage
Carotenoids (beta-carotene) histamine ceramides Linoleic acid
Flavonoids Serotonin Phytosterols protein
Mineral salts Phenylpropanes Tocopherols
Organic acids lignans
Provitamin A Monoterpendiols
mucilage agglutinin
Scopoletoside Scopoletoside
Sitosterol polysaccharides

The general effects indicated in the commercial nettle extracts They include foliar fertilizer, growth stimulator, iron chlorosis control, pest and disease prevention, and insect repellent.

At the nutritional level, the content of minerals and micronutrients assimilated by plants is considered low, but at high concentrations (10-15%), it can act with a mild biostimulant stimulussince nitrogen comes from free amino acids such as asparagine and arginine (representing 80% of the total).

Analysis of the chemical composition of the usual nettle manure (dilution 1/10):

pHMO. (%)N (%)P2O5 (%)K2O (%) Proteins (%) Micronutrients
7.5-8.5 0.5-1.0% 0.005% 0.002% 0.015% 0.03% tracks

Source: Garmendia A, Raigón MD, Marques O, Ferriol M, Royo J, Merle H. Effects of nettle suspension (Dioecious urtica L.) used as a foliar fertilizer on potato yield and growth (Tuberous solanum I.). PeerJ. 2018; 6: e4729. Published May 7, 2018. Doi: 10.7717/peerj.4729

How to make nettle puree

For the preparation of our nettle-based compound, we will differentiate between 2 components: nettle manure (fermentation/maceration) and nettle extract (cooking). The first is generally used for its nutritional contribution, and the second, where a greater concentration is obtained, for application against pests and diseases.

The concentration of nettle manure is generally 10% (1 kg of fresh nettle for 10 liters of water). On the other hand, for its activity as a Basic Substance, a much higher concentration is needed (75% fresh nettles or 15% dried nettles).

Depending on the fermentation time, it can be classified in 3 different ways:

  • Macerated nettle extract: 12 to 36 hours
  • Fermented nettle extract: 10 to 15 days
  • Ripe nettle porridge: >15 days

Generally, what we want to apply to the plants is a fermented extract of nettles, so the The average time will be between 10 and 15 days.

nettle porridge

For the preparation of nettle porridge, we do not need a lot of ingredients, just entertain them by selecting fresh nettle leaves (large nettle and small nettle, preferably), performing this task with gloves because this plant has a pungent activity.

Let’s see what we need.

Ingredients used:

  • 10 liters of water, preferably rainwater.
  • 1 kg of fresh nettle (harvested before flowering).

Enter the fresh nettle leaves in the container, to which you will add drinking water, respecting the previous proportion. That is 100 grams of fresh nettle leaves per liter of water. Shake the mixture vigorously and try to leave all the leaves submerged in water.

Cover the container, but do not seal it tightly. This way you will activate the fermentation process. You will notice a powerful unpleasant odor emanating from the container, so it must be tightly closed. Move every 2 days and leave to ferment for 10 days.

After 10 days, filter the fermented nettle manure and keep it in an environment protected from light and at a temperature not exceeding 30ºC.

Nettle extract as an insecticide/fungicide

According to the Basic Substances Regulation, HEALTH/11809/2016there is a specific concentration according to the pharmacopoeia from which there is complete activity on pests and diseases, which we will specify later.

  • Cook the nettle leaves, fresh (75 g/L) or dry (15 g/L) (we choose the young shoots that have not become seeds; they are cleaned and washed) in drinking water. Fermentation can be facilitated if the nettle is chopped beforehand.
  • Stir the mixture daily.
  • Leave to macerate for 3 to 4 days at 20°C (unless otherwise indicated in Appendix II).
  • Filter the maceration and dilute the filtrate in 5 times its volume of drinking water in a closed and identified container.
  • Make sure the pH is between 6 and 6.5 to ensure good manufacturing.

What is nettle manure used for?

Generally, nettle slurry can be used to enrich a compost mix, to contribute directly to the soil (nutrients + microbiological prebiotic) or, in a higher concentration of fresh leaves, as a pest and disease repellent and control.

In the latter case, as anything called an insecticide/acaricide/fungicide requires special permission, nettle extract is currently classified as basic substance in Europe.

Nutrient intake

Promote mulch or plant cover

Mix the dry plant matter (aerial part) with the mulch at a rate of 83 g per kg of mulch. Thus, although the nutritional contribution is not very high (see composition table), it contains organic complexes that can promote the multiplication and development of natural microbiology, acting as a prebiotic of the compost.

Direct floor application

As if it were a fertilizer, using high concentrations (10%, equivalent to 100 ml per liter of water) we can apply directly to plants or create a repellent effect on soil insects.

Insect control

The first thing to keep in mind, according to the recommendations of the basic substance, is that preventive foliar treatments have no impact on preventing the proliferation of the pest if it is not yet in the crop. That is to sayhas no systemic activity the only source of protection provided by the extract or the slurry of nettle is not either the nutritional improvement and the contribution of antioxidants.

However, yes it can have repellent activitywhich reduces the likelihood of the pest acting on the plant, especially when it has other feeding possibilities (plants not treated with nettle slurry).

CultivatedPlagueDoseAdvice
leaf crops Aphids (different types) 1.5L/100L Early stages of development
stone fruit trees Aphids (different types) 1.5L/100L Applications every 7 days
pome fruit trees Codling moth (Cydia Pomonella) 1.5L/100L Applications every 15 days
Bean black aphid (Aphis fabae) 1.5L/100L Apply at all stages of cultivation
Potato potato aphid (Myzuspersicae) 1.5L/100L Apply until the end of tuberization
crucifers Broccoli flea beetle, Plutella 1.5L/100L Applications every 7 days (up to 6)
Vineyard Mites (Tetranychus urticae and Tetranychus telarius) 1.5L/100L Up to 6 foliar applications

for emite controlwith only a maceration of 24 hours at a temperature of 20 ºC, excellent results can be obtained, being constant in the application (up to 6 foliar applications with a margin between applications of 7 days).

disease control

Against diseases, it has preventive and curative activity, according to European documentation on nettle extract.

VScultivationDiseaseDoseAdvice
crucifers alternate 1.5L/100L Apply until BBCH49
cucurbits Mold and Alternaria 1.5L/100L Apply every 7 days (all stages)
stone fruit trees Alternaria, Monilia, Botrytis, 1.5L/100L Apply every 7 days (all stages)
Vineyard Mold 1.5L/100L Apply every 7 days (all stages)
Potato Phytophthora 1.5L/100L Apply every 7 days (all stages)

Associated products

Bibliographic references

  • Basic substance Urtica spp. HEALTH/11809/2016–rev. 0.1 – January 24, 2017

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