Fertilize hemp for a high yield harvest

Hello dear Bonsanto Community,

As of now, our much sought-after 35-watt LED lamp is available again.

The 35 watt LED plant lamp is our "queen" because it has the following advantages:

Effective and innovative: you do not have to change the lamp between growth and flowering phase. One lamp for all phases.

Cool in operation: it is significantly cooler than other comparable LED plant lamps.

Power saving: It is absolutely power saving. Herewith you get the highest yields at very low electricity costs.

Have fun with it!

Let the growers grow!

Fertilize hemp

In order for your cannabis plant to grow strong and thrive, you should provide it with fertilizer. Learn everything you need to know about fertilizing cannabis and how to recognize nutrient deficiencies and surpluses in our blog.

If you are growing in our Bonsanto Mini grow box and using our grow box specific fertilizer, you should first and foremost follow our Bonsanto growing guide . You can find more tips and advice in this blog post.

Table of contents

Why should you fertilize hemp?

In order for you to have a bountiful harvest and for your cannabis plant to grow optimally, you need to provide adequate nutrients and fertilize your plants. Cannabis has a high demand for nutrients. This occurs especially in the growth phase and the flowering period.

In addition, fertilizing cannabis can promote the growth of your plant. The nutrients contained in the fertilizer, such as potassium and nitrogen, support plant growth and contribute to the development of strong leaves and plant roots. Likewise, nutrients support the formation of buds or flowers. So if your cannabis plant is supplied with sufficient nutrients, you can expect a bountiful harvest!

Another reason why you should fertilize your cannabis is to avoid deficiency symptoms such as yellow leaves or high susceptibility to diseases. If you fertilize your cannabis plant sufficiently, you can avoid these problems.

What nutrients does cannabis need?

For healthy plant growth, cannabis needs some nutrients. The nutrients that are most important for your cannabis are the so-called macronutrients nitrogen (N), phosphorus (P) and potassium (K). Nitrogen is especially important in the growth phase of cannabis, as it promotes the development of leaves and stems. Phosphorus is a substance that is essential in the flowering phase, as it supports the formation of buds. Potassium strengthens the plant and facilitates nutrient absorption. The NPK number shows you the ratio of the three macronutrients in a fertilizer. Example: If your fertilizer is labeled NPK 5-20-10, this means that the fertilizer contains 5% nitrogen, 20% phosphorus and 10% potassium.

Also secondary nutrients such as calcium, magnesium and sulfur should also be included in your fertilizer. Calcium regulates the pH of the grow soil and also promotes plant growth. Since magnesium is important to the process of photosynthesis, it is also among the necessary nutrients for your plant. Sulfur is used by plants for chlorophyll formation and the production of vitamins and other important proteins.

Moreover mirconutrients include, for example, iron, copper and zinc. These substances are also important for your hemp plant, even if they are only needed in small quantities.

Fertilize hemp nutrients

When should you fertilize hemp?

When exactly you should fertilize your cannabis basically depends on various factors. Depending on which fertilizer you use and in which growth phase your cannabis is, the fertilization time can be different.


When you buy a fertilizer, you will usually find instructions from the manufacturer regarding the dosage. These instructions should be used as a guide when you want to provide your cannabis plant with nutrients. We recommend that you start fertilizing cautiously and wait to see how the plant reacts to the nutrients, because too high a dosage can lead to problems. How you can recognize an excess, we explain in one of the next sections.

When growing in our Bonsanto Mini Growbox and using our"Organic Boost" fertilizer and/or use the "Extreme Energy" Concentrate follow our growing guide. Start using the Organic Boost fertilizer from the 2nd week after germination. From the 7th week you can add the "Extreme Energy" concentrate.

Growth phases

If you look at the growth phases, you can do without fertilizer in the seedling and cutting phase. If you use a pre-fertilized grower soil, such as our Bonsanto Premium Soil, this is already sufficient in most cases. The cotyledons of your cannabis plant still contain enough nutrients in this phase. If you give your plant too much fertilizer in this phase, this can even hinder growth and harm your plant.

In the Growth phase , the whole thing looks different. To promote healthy plant growth and strengthen your plant, you can supply your cannabis with fertilizer in this phase. This is also advisable when your plant goes into Flowering . Also in this phase cannabis needs nutrients to form buds and resin.

It is important that you stop fertilizing in time so that there are no fertilizer residues in your harvest and the taste when smoking does not suffer. We advise you to stop fertilizing about one to two weeks before harvest. 

Fertilize cannabis plant

How much and how often fertilize?

A general statement about how much fertilizer a cannabis plant needs cannot be made. There are several factors, but you should orient yourself.

As just mentioned, first follow the fertilizer manufacturer's dosage instructions. Each fertilizer behaves differently and may contain a different composition of nutrients. The manufacturer knows these properties best, so the dosage instructions should be followed. If you do not find information from the manufacturer about how often you should fertilize, you can use the fertilizer about 1 time a week. Depending on how your plant responds, you can then increase or decrease the dose. With Bonsanto fertilizer "Organic Boost" we advise a fertilizer quantity of 20 drops per liter, whereas with the concentrate „Extreme Energy“ 10 drops per liter are sufficient.

Basically, it is important that you monitor your plants to determine if they need more nutrients or if they are oversaturated. If you notice a deficiency or over-fertilization, you should of course adjust your fertilization method. If you are new to growing, take it slow and use too little fertilizer at first rather than too much.

Wie oft Cannabis düngen

What are the methods of fertilization?

If you want to fertilize your cannabis, you can choose between different fertilization methods. It is advisable to use a high quality fertilizer that has been specially developed for the cultivation of cannabis. In our store you can find the Bonsanto "Organic Boost" fertilizer as well as the "Extreme Energy" concentrate, which are specially designed for indoor growing. Keep your hands off fertilizers from the hardware store. In order not to harm your plant, you should not save here at the wrong end!

Organic fertilizer

One of the most popular fertilizers among growers are organic fertilizers. These are environmentally friendly and consist of natural materials such as compost. The advantage of organic fertilizer is that the plant absorbs the nutrients with a time delay, which is why overfertilization is usually excluded with this fertilizer. However, if your plant shows signs of nutrient deficiency, you will have a hard time fixing it with an organic fertilizer. If you are a beginner grower, we would recommend using an organic fertilizer.

If you use soil containing microorganisms as a grow substrate, use an organic fertilizer. The microorganisms convert the organic matter into food for your plants. If you were to use an organic fertilizer in combination with a substrate such as perlite or coco or a soil without microorganisms, the conversion would not take place and your plant would not be able to absorb the fertilizer.

As an organic fertilizer we recommend our Bonsanto fertilizer "Organic Boost". This is 100% organic and suitable for any indoor grower. Even if you grow in one of our mini grow boxes, the fertilizer is the optimal solution to accelerate the growth of your plant without the plant becoming too big for the box.

Mineral fertilizer

An inorganic fertilizer is the mineral fertilizer. This provides nutrients in a concentrated form and allows growers to supply nutrients directly to the cannabis plant. Thus, with a mineral fertilizer, you have more control over the nutrient supply to your plant. Mineral fertilizers are usually less expensive than organic fertilizers. However, if you use this fertilizer method, you must be careful not to over-fertilize! 

If you are using a growing medium such as coco or perlite, use a mineral fertilizer. Mineral fertilizers can also be used if your plant is growing in growing soil. In this case, it is also okay if the soil does not contain microorganisms.

Mixed fertilization

If you want to use the advantages of both fertilizers, you can also use a mixed fertilization. By combining organic and mineral material, your cannabis plant will be optimally supplied with nutrients. A mixed fertilization is usually easier to use than a purely mineral fertilizer.

How do you recognize nutrient deficiencies?

As mentioned in the previous sections, it is important that you regularly check your plant for nutrient deficiencies. This way you can tell when your cannabis needs more fertilizer.

The most common sign of nutrient deficiency is yellow discolored leaves. Depending on the discoloration, you can even tell exactly which nutrient your plant is lacking. Magnesium deficiency is manifested by yellow spots, whereas a lack of nitrogen can be recognized by generally yellowish discolored leaves.

Deformation of the leaves and leaf drop can also be indications of a nutrient deficiency. If your cannabis plant is supplied with insufficient magnesium, the leaves curl. If the leaves grow slowly, this may indicate a phosphorus deficiency. If the leaves of your plant fall off, your plant is clearly undersupplied.

If you notice that your plant is growing slowly, this may also be due to underfertilization. If important nutrients are missing, it is not able to grow. Low flower formation and small buds can also indicate a deficiency.

If you suspect that your plant needs more nutrients, you should adjust the fertilization. Therefore, check your cannabis regularly and see how the plant reacts to the fertilization.

Fertilize hemp detect nutrient deficiency

How do you recognize nutrient excess?

Overfertilization can be just as harmful as a nutrient deficiency. Therefore, a balanced fertilization program is important for healthy growth.

If you have overfertilized your cannabis plant, you can tell by different signs. An indication of nutrient overuse is brown and curled leaves. Also, if your leaves become darker and shinier, this may be due to the use of too much fertilizer. If the lower leaves of your plant fall off, but the upper leaves look healthy, you should also consider overfertilization.

If you feel your plant is suffering from an excess of nutrients, there are several ways you can respond. Probably the most obvious is to significantly reduce the amount of fertilizer you use. To flush nutrients out of the soil, you can add pH neutral water to your soil. Also, measure the PH of the soil. If the soil is not in the optimal range for your cannabis plant, i.e. has a value that is not between 6 and 7, make sure that the pH value levels off again. The pH value affects the nutrient uptake of the plant and can therefore be a cause of overfertilization.

Cannabis Overfertilization Detect
Recognize hemp overfertilization

Tips for fertilizing hemp

To help you fertilize your hemp successfully, here are two tips for you:

  • Rinse before harvest: To achieve a flavorful smoking experience, you can rinse your plant with pH-regulated water one week before harvest. This will prevent nutrient residues from being present in your crop.
  • A deficiency is easier to correct: Since it is easier to make up for a nutrient deficiency than it is to correct an over-fertilization, we advise you to always start fertilizing cautiously and see how your plant responds to the nutrients.
  • Use our Bonsanto "Organic Boost" for fertilizing! This is beginner friendly and over fertilization is virtually impossible. 
Fertilize hemp for a successful harvest

Fertilize hemp - overview

  •       Plants need nutrients for healthy plant growth
  •       Fertilizer promotes the growth of your plant, health and the formation of buds
  •       Macronutrients are most important for your plant
  •       How much fertilizer the plant needs depends on the growth phase
  •       Follow the dosage instructions of the manufacturer
  •       Fertilize carefully at first and see how your plant reacts to the nutrients
  •       For fertilization you can choose an organic or a mineral fertilizer
  •       The organic fertilizer protects against overfertilization
  •       Mineral fertilizers can be directly absorbed by the hemp plant
  •       Start fertilizing from the growth phase
  •       Stop fertilizing about one to two weeks before the harvest
  •       Try to avoid both nutrient deficiency and nutrient excess

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