Best Nutrients for Cannabis Flowering Stage

Your cannabis plants have been in the vegetative stage for a while now. They grew in size, developed a vigorous structure, and plenty of fan leaves. When the female plants grow small white pistils from the nodal areas, they?re signalling that it?s time for the flowering phase. During this phase, buds grow and develop a solid cannabinoid and terpene profile.

Outdoors, the flowering phase begins naturally with the fall season, while indoor growers need to kickstart the flowering phase by changing the light cycle from 18?6 to 12?12 hours of light and darkness. Before we proceed with the details, it?s important to note that the main mistake growers make during the flowering phase is overfeeding plants. Just because buds are forming doesn?t mean that they need to be blasted with fertilisers and boosters; this often leads to nutrient toxicity. As a rule of thumb, less nutrients produces better results. If nutrient deficiency is detected, one should gradually add the necessary compounds into the mix.

Which elements does a cannabis plant need?

Your cannabis plant needs a main group of elements that are collectively referred to as macronutrients. Here?s a breakdown of the mineral and non-mineral elements you need to feed your plant.

Mineral nutrients obtained from the soil:

Nitrogen (N)

Phosphorus (P)

Potassium (K)




What Nutrients Does Cannabis Need to Grow?

Nutrients are used like food by plants. Cannabis requires large amounts of mineral nutrients to compose it?s leaves and dense flowers. The best nutrients for cannabis are in fact the nutrients which are used by the plant to support growth.

Well-fed cannabis plants are green and healthy, which can lead to increased flower production and higher yields of bigger buds. Well-fed plants have a stronger immunity to disease than underfed plants.

Underfed cannabis plants are often slow to grow, stunted, yellowing and frail. The buds develop sparsely and produce a lower quality and yield than well-fed plants. Underfed plants have a weak immune system due to lack of nutrients.

There are six major nutrients that cannabis plants require to grow ? three of which are obtained from the air and water:

Carbon Dioxide (CO2) ? Plants simply absorb CO2 from the air, combining it with water and light, to make carbohydrates ? a process more commonly known as photosynthesis.

Hydrogen (H) ? Hydrogen is a part of water (H2O). As plants absorb water, they split the water molecules into hydrogen and oxygen using the energy from the sun.

Oxygen (O) ? Along with what has been described above, plants consume oxygen through their pores ? even at night. This is what?s called respiration. Respiration combines oxygen and the food created during photosynthesis to produce usable energy for plants.

The other three nutrients are Nitrogen (N), Potassium (P) and Phosphorus (K). These nutrients are mostly obtained though a plant?s roots, but can also be absorbed through tissue (i.e. foliar feeding).

What About Organic Nutrients?

One thing to note here is that when you are growing marijuana in soil, you would be wise to go with organic nutrients. This way, you know exactly what you are feeding your plants, and therefore there is nothing to worry about when you consume it.

However, beware that you should not really be using organic nutrients for hydroponic grow operations, as they may cause the growth of bacteria in the water and may mess with pH levels.

Flowering Nutrients & Sativa vs Indica

Something else not note here is that there are of course 2 main different kinds of marijuana, these being cannabis Indica and cannabis Sativa.

What you need to know here is that cannabis Indica plants can usually handle a lot more nutrients than cannabis Sativa plants.

Simply put, cannabis Sativa plants do not require as high a level of nutrients for proper growth, which is true for both the vegetative state of growth as well as the flowering stage.

Before you begin feeding your weed plants any nutrients, it is wise to look up the nutrient requirements of the specific marijuana strain you are growing.

What is the best nutrient ratio for the flowering stage of cannabis?

During this period, nitrogen should be the lowest. A beneficial N-P-K ratio formula is 1?3?2 in the early stages of flowering up until the mid-blooming stage and a 0?3?3 in the last stages of blooming. Finally, you can give the plants a light flushing solution together with fresh water in the final week before harvesting.

How long is the flowering stage?

When planting your cannabis indoors, the flowering period begins the moment you start switching your grow lights for equal 12 hours of daylight with 12 hours of darkness. Depending on the cannabis strain, the period can last for seven to nine weeks.


? Light: Grow Lighting during the flowering phase should be stronger in the ?red? wavelength spectrum as opposed to ?blue? wavelength spectrum during veg. The light cycle should be switched to 12?12 for indoor operations unless we?re dealing with autoflowers, which can handle longer light periods.

? Temp/humidity: For photoperiodic plants, mimicking the differences between summer and fall by making the light cycle shorter and the temperatures slightly lower is good practice. Lowering the temps by 2?3C during the flowering phase will do great, but it?s not necessary to develop high-quality buds. The humidity levels should not surpass 50%, otherwise the buds can begin to rot.

? pH: For soil-grown cannabis, 6.0?6.5 pH levels are ultimate, for hydro, 5.5?6.0pH does the trick.

? Ventilation/circulation: Good air circulation is important during every phase of growth. Something to consider during the flowering phase is that buds exude pungent aromas, which can be detected by neighbours quite easily.


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