For their growth, plants need various elements for their development. These are divided into three groups, the primary elements, the secondary ones and the micro elements.

The primary elements are Nitrogen (N), Phosphorus (P) and Potassium (K) which are always indicated in the order N-P-K. They are considered primary elements because they are the ones that plants consume in greater quantities.

The secondaries are Magnesium (Mg) and Calcium (Ca).

Micro elements are consumed in very small quantities and are often present in the seeds if of quality. We are talking about Iron (Fe), Sulfur (S), Manganese (Mn), Boron (B), Molybdenum (Mb), Zinc (Zn), Cobalt (C), Chlorine (Cl) and Copper (Cu).

The first of the primary elements is nitrogen, the most important as it allows the plant to create proteins essential to create new tissues and is involved in the production of chlorophyll. It directly affects growth in general and is of vital importance especially during the vegetative growth phase in large quantities, while it is less necessary during flowering.

We can say that the percentage of nitrogen (N) in the fertilizer to be used during vegetative growth must be higher, while it should be lower during the flowering phase.

Phosphorus (P) is also very important for photosynthesis. Cannabis plants need large contribution of phosphorus during germination, cloning and especially throughout the entire flowering period.

Earth Worm Castings – Compost Soil Amendment – 5 Gallons – 30 Lbs

Price: $58.75

The third primary element is potassium (K). It is associated with the creation and transport of sugar and starch, as well as the increase of chlorophyll in the leaves.

Potassium is essential for good root development and plant resistance to diseases and parasites. This element is used throughout the cycle.

Secondary elements Mg and Ca: Magnesium is essential to allow optimal absorption of light as well as other nutrients. Calcium, on the other hand, is essential to allow the creation of new tissues and allow optimal growth.

The most important of the micronutrients is Iron. Its deficiency normally presents itself as a yellowing of leaves and shoots with the capillaries of the leaves remaining green.

If the fertilizers also contain micro elements in relevant percentages, they should be indicated, otherwise they must be supplemented individually.

Fertilizers and fertilizers in general, of whatever origin they are, have three numbers marked which indicate the percentages of the three primary elements: N-P-K, Nitrogen, Phosphorus and Potassium (for example 15-30-15).

What we are interested in knowing is the proportion of one element to the other. In the example above, the amount of phosphorus is double that of nitrogen and potassium.

Roots Organics HPK Bat Guano and K-Mag 0-4-3

Price: $17.45


Fertilizers for the vegetative growth phase must have a high nitrogen content, and are marketed as fertilizers for green plants. Those best suited to the flowering phase contain more phosphorus than nitrogen, so the second number must be greater than the first.

Know that there is nothing more harmful than excessive fertilization, which can lead to irreparable damage to the plant by burning its roots and leaves. If over-fertilizing is minor, you will notice the tips of the leaves getting burned. To solve this, a thorough rinsing of the vase might be enough. In the case of a strong over-fertilization, on the other hand, the leaves will burn and curve downwards. In this case we will hardly be able to save the plant.

Generally, there is no need to fertilize the plants more than once a week, always respecting the specific indications of the fertilizer used. While the absence of an element can be integrated, the excess fertilization is difficult to reverse.

Most of the organic materials that can be integrated into the soil such as cornwall, humus or manure. These are slowly assimilated by the plant and are unlikely to cause over fertilization issues compared to industrial fertilizers. They are also natural, cheaper and sustainable.

In the case of soil properly prepared with organic fertilizers there is no need to add other fertilizers during the vegetative growth phase.