Protect your crops with plant extracts

Today at Gardenprue we dedicate the entry to plant extracts . It is something like extracting the juices of some crops that interest us through some chemical or physical processes and applying them to those plants that we want to protect. It is very interesting and of course, totally ecological. Do you want to have a totally organic garden? We have to tell you this. 


How can it be that something used by the pharmaceutical industry , the cosmetic industry and even us as curative remedies is not used for plants as well? We are talking about plant extracts . It is a very studied world that, however, and I do not know for what reason, does not apply much in the plant world. It is not necessary to go very far, in Nature we will find many answers. We, as human beings, have been able to take advantage of these properties for a long time, but always for ourselves, and we have preferred to leave it in the hands of chemistry (whose current role in agriculture as we know it is irreplaceable) or who knows what the solution to the main problems of plants.

Well, just as some medicinal plants can alleviate some physical problems, they are also capable of doing so, in their own way, with other plants. It is something like plants that heal other plants .


Having ready-to-use plant extracts to cure other plants relies on fermentation . It is a process similar to wine and must be controlled, knowing the duration of the phases and the period in which the extract or slurry will be ready. However, 8 out of 10 attempts end in a prolonged mash, which of course smells awful. This is the great secret, if the fermentation is done well, the extract does not have to smell bad and therefore should not be called slurry.

The objective of an extract is not to kill the plague , but rather to have a protective function. Somehow we cannot measure the results visually with a magnifying glass looking for samples of bodies of insects whose extracts have ended their lives. It has other functions whose dynamics are being used a lot in current phytosanitary products, not as toxic as in the past. It is based on blocking the changes of stages or cycles of insects , such as blocking the laying or the molt. This makes the jump in resistance to the product much more difficult than those products that use other ways to end the pest, which in the long run, when used with great frequency, end up becoming harmless products for the pathologies of the crops. .

Just fight pests? No, also reinforce. Of all the plant molecules that an extract is composed of, there are those that are capable of regulating the activity of the crop that we want to protect, increasing resistance and reducing its vulnerability to future unexpected visits. And although it seems that we are only talking about pests, there are also remedies from plant extracts for diseases .


Despite what some of us thought (perfume always in a small bottle) the quantity is important when making plant extracts . Large amounts of plant extract production (50 liters and up) are recommended to improve fermentation quality and better control temperature fluctuations. Of course, all these are recommendations and will depend mainly on the size of our garden or orchard and the needs we have.

As a recommendation, they specify 1 kg of fresh vegetables for every 10 liters of water to make plant extracts , although in some cases the amounts are usually lower (for example, in nettle, 800 grams is preferable instead of 1 kg). Note that collecting 1 kg of nettles, since we have mentioned them, is very easy, it grows wild throughout our garden and until recently, we surely despised it.

The fermentation is the secret of the extract of plants, and linked to this process is the temperature. It will depend on this to achieve in a few or many days a perfect slurry to apply to our plants. As an average to say according to the book of plants to cure plants that a fermentation between 18 and 20 ºC of nettles would be ready in just 15 days.

When we get past these days and we are not aware that the fermentation process has already finished, this is where the real bad smell begins (the previous one is controllable) and when the product can start to spoil. One must be careful with that. One trick is to stir daily to get a more homogeneous mixture and especially to control the bubbles . These will tell us how the fermentation process of the plant extracts is going. If no effervescent bubbles appear when stirring, the fermentation will be over and the broth will be ready to use.

Nettle extracts elaboration process
Source: faenasdelahuerta


Although any plant that we collect from the field has, to a greater or lesser extent, a function, although there is a list of those that have truly been shown to have a very high capacity to help other plants. The following plant extracts are widely used:



  • Wormwood infusion (100 g / L in 20% dilution), to prevent the entry of insects into the crop.
  • Macerate 500 g of rhubarb leaves in 3 liters and make 3 treatments, one per day to avoid the plague.
  • 100 g of garlic minced and macerated with 2 tablespoons of olive oil and 1 liter of water resting for 1 week diluting the broth to 5%. Insecticidal remedy.
  • Infusion of fresh nettle leaves (100g / L).


  • Horsetail decoction (100g / L) and dilute to 20%. Do 3 treatments 1 week apart
  • Macerating nettles (100g / L). 3 treatments in 30 days.


  • Decoction of 50 grams of horsetail per 5 liters of water and boil for 1 hour, then diluting to 20%.
  • Garlic root decoction   (100g / L), previously soaking for 24 hours. Then boil for 30 min.


  • Decoction of 50 grams of horsetail for every 5 liters of water Boil one hour and dilute to 20% and apply 3 to 5 treatments at 7-day intervals.

These are, by way of example, some of the remedies against pests and diseases extracted from other plants and whose information is collected in the book plants to cure plants. There are so many more!

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