Natural insecticides

Natural insecticides (prepare the nettle macerate)

Among the natural insecticides, one of the most important for the family garden is nettle macerate, because in addition to being completely organic, it can be self-produced very simply, with great economic savings compared to the pesticides found on the market.

Nettles are a very common spontaneous herb and very easy to recognize, which is why they are an easily available ingredient for making an organic and economical pesticide, which does not require a license for use. Nettle leaves are stinging and contain formic acid and salicylic acid, properties that we are going to use against parasites.

In addition to the use of insecticides, we can also obtain fertilizer from macerated nettle. The recipe is very simple: just leave the leaves to soak for a longer period of time to extract the many useful substances of the plant and make them available to the plants as foliar fertilization.

As you may have guessed, nettle is really an important plant essence for natural cultivation, we see below where to collect it, how to prepare its macerates, with dosages and directions for use.

How to prepare the nettle macerate

The nettle macerate recipe is really very simple, timing and dosages are indicative. The following are the recipes and periods that I use, but it is also possible to use different quantities of plants, obtaining a more or less diluted product. In the preparation, it is important to define whether we want to obtain an insecticide or a fertilizer since the infusion times depend on this.

Find out more about Nettle: properties, benefits, uses in the kitchen.

The insecticidal nettle macerate

The preparation of the insecticide macerate, which we will call short macerate, is really simple: you need about a kilo of nettle plants cut at the base (the roots are not needed for the preparation), which we must macerate in 10 liters of water. It is better to use rainwater, if you really use that from the water supply, let it settle for a few hours after removing it from the tap so that it loses some volatile disinfectants (especially chlorine). The use of fresh plants is preferable, but failing that we can also macerate dry leaves, in this case, the ratio becomes 100 grams per 10 liters.

To obtain an insecticide macerate, the infusion time is one or two days, after which the compound must be filtered and is ready to use, spraying it on the plants without dilution.

Among the side effects of this preparation, there is certainly its pestilential stench, unwelcome to insects but also to humans. It is worth bearing it, considering how much the nettle macerate is useful for the organic garden.

The fertilizer nettle macerate

Fertilizers can also be obtained from nettles, leaving them to macerate for longer than the two days we considered for the insecticide. Nettle leaves contain useful substances such as nitrogen, magnesium, and iron, for which we will obtain a precious liquid organic fertilizer.

The dosage is identical to that of the short macerate, so 100 grams per liter in the case of fresh plants, or 10 grams of dry leaves. What varies is the infusion period, in fact for the fertilizer, we have to let it macerate 10/15 days.

Find and recognize nettles

Natural insecticides

If we want to prepare the macerate for free we must be able to find and recognize nettle plants in nature, going to pick them. First of all, it is better to know that the best time to do it is before the plant’s bloom because flowering involves a waste of energy and nutrients that impoverish the properties of the plant. However, it happens that you have to adapt to what you find and the macerate has its effectiveness even if you catch nettles in bloom.

Nettles are a spontaneous plant, easily recognizable by their appearance: the emerald green leaves with serrated edges are characteristic. To remove any doubts, even if it is unpleasant, we can try to touch a leaf, which is covered with stinging hairs. If we feel the classic sting, we have almost certainly identified the right plant.

Once the nettle has been identified, it is advisable to use gloves for harvesting, so as not to find your hands covered with irritation.

The nettle plant prefers soils capable of retaining moisture and very rich in organic matter and nitrogen. If we want to know where to find it, let’s take it into account: we can look for it in uncultivated areas of partial shade, perhaps frequented by animals that with their manure provide the elements loved by this spontaneous grass.

Preservation of the insecticide

The short nettle macerate is kept for little, after a few days it loses its effectiveness, so it is better to prepare it just before use.

Use of the insecticide macerate

As an insecticide, the nettle infusion is excellent in particular against plant lice (aphids and cochineal), as well as being an acaricide product, making it perfect for fighting red spider mites. Its effect is largely due to formic acid. a substance that makes nettle leaves sting. On many other animal parasites, for example against some Lepidoptera such as the moth or against the dipterans that afflict the orchard, it still has a repellent effect, while it does not work against cabbage, which indeed seems to be attracted to nettles. In any case, it is a useful insecticide if used at the beginning of infestations, as it struggles to effectively counteract a significant settlement of parasites.

The use is very simple, it is done by spraying the preparation over the entire aerial part of the crops to be protected. We can repeat the treatment after 4 or 5 days, to best eliminate the parasites. We avoid doing treatments in the hottest and sunniest hours.

We can do both preventive treatments and to get rid of an infestation already in progress, in this second case it is better to repeat the treatment after 4 or 5 days with a second pass, to eliminate a greater number of parasites.

Precautions and waiting time

We recommend two precautions when using this organic insecticide: the first is to be careful where you leave the bin with the macerated product because the stench could annoy the neighbors, especially if you do the long maceration.

The second, more serious, is to be careful because the nettle macerate bothers all insects, even those that are useful in the garden: it is slightly toxic, for example, for bees. As a shortage period, we recommend letting 5 days pass, however it is a pesticide that has no impact on the environment and naturally degrades.

The fertilizer nettle

The long nettle macerate is used as a precious fertilizer, thanks above all to the rich presence of nitrogen, and also to reintegrating iron and magnesium. After preparing it, we can dilute it one to ten and use it as irrigation water for the garden.

A particularly valid use is in pot cultivation, given that a limited soil offers fewer nutrients to crops and requires more frequent fertilization.

Other uses

The macerate also has the effect of reinforcing the natural defenses of plants against some pathogens, due to the salicylic acid present in the nettle tissues: powdery mildew, peach blister, tomato, and potato blight. It is not a decisive treatment but it helps in prevention. For this use, fertilizer macerate is better.

There are those who also use the long macerate of nettle on the seedlings at the time of transplanting, wetting the roots, and those who consider nettles a good activator of composting.

Buy nettle extract

If you are very lazy or can’t find nettles in your area, you can also decide to buy products made from nettle extract, which are therefore natural and environmentally friendly preparations. The fact remains that it is a pity to pay, not even a little, to have something that can be self-produced. When there is no time, however, it may be worth taking the shortcut to the ready-made extract and it is always better than spending it to buy toxic pesticides or fertilizers.

We find both insecticide and fertilizer extracts on the market.


You may be interested to read about the Red spider mite blogpost/ Powdery mildew blogpost/ Rock powders in agriculture blogpost/ Care plants with propolis blogpost/ Horsetail for diseases, parasites blogpost/ biological fungicide blogpost/ Feed plants with algae blogpost/ Whitefly on plants blogpost/ barbecue sauce recipe.

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