Npk: What Is The Best Ratio For Growing Cannabis

Perhaps you’re new to cannabis cultivation or struggling with macronutrient deficiencies? Maybe it’s overfertilisation that’s spoiling your marijuana? Whatever substrates you grow with, plants need the right nutrients at the right time. Eliminate the doubt and subpar harvests with our NPK intel.

NPK: What Is The Best Ratio For Growing Cannabis

The Simple Guide To Npk Ratios For Marijuana

Nutrients are a critical factor of cannabis cultivation. The trio of macronutrients nitrogen, phosphorus, and potassium are the fuel for the marijuana growth engine. NPK base nutrients cannot be applied in the same ratio for the complete cannabis lifecycle.

Moreover, cannabis plants differ significantly in nutrient requirements from strain to strain. All things considered, it’s no surprise that figuring out the correct ratios to dose plants can be complicated. Allow us to simplify cannabis plant feeding for growers of all levels.

Changes In Nutrient Requirements

Vegetatitve Growth

Vegetative Growth

Early in the cannabis life cycle, nutrient requirements are minimal. Less is most definitely more. Most growers favour a high N feed. An NPK ratio of 3:1:1 during the growth phase is an excellent macronutrient feed for virtually all cannabis strains. Of course, some strains will respond better with some slight tweaking.

It’s not all about nitrogen, but N levels should always be proportionately higher than phosphorus and potassium until bloom. Nitrogen-rich feeds are not required for soil growers as most high-quality cannabis soils contain enough fertiliser for the first 3-4 weeks. Just add water and keep an eye out for nutrient lockouts. Alternatively, Easy Grow tablets can slow release nutes during vegetative growth.


Flowering Phase


As cannabis plants transition into flowering, macronutrient requirements swing in the opposite direction. That means switching to bloom base nutrients and adjusting the NPK ratio. A highly effective NPK formula is 1:3:2 for early to mid-bloom, followed by 0:3:3 for late bloom. Add a final flush of pure water and/or light flushing solution during the final week for flavour. Then, it’s time to harvest. P & K dictate the quantity and size of bud, respectively.

Thus, tapering off N levels while simultaneously increasing P & K is the primary grower objective. Too much nitrogen late in bloom spoils the sinsemilla. Buds will taste harsh and just won’t smoke as smoothly as a thoroughly-flushed stash. Leave out the N altogether for the final 20-30 days.

Every cannabis strain has its own nuances. This is true when it comes to nutrients and feeding too. Regardless of whether you intend to use organic or chemical fertilisers, you must incrementally increase doses. You simply cannot launch right into full-strength feeds from the get go. Again, Vertafort slow release organic bloom tablets are a viable alternative as they time-release nutes throughout flowering.

Feeding: Heavy, Light, And Just Right

Feeding Heavy And Just Right

As mentioned earlier, soil growers really only need to water plants through the seedling stage. Typically, adding beneficial microorganisms and enzymes is enough. These will help roots develop and make nutes in the soil readily available. However, hydro and coco growers are advised to start by applying 25%-strength feeds and work up from this base level.

Some strains, especially indica varieties, tend to respond better to higher doses of fertiliser; the more sativa present usually corresponds to fewer nutes required. Hybrids and autoflowering strains occupy the middle ground, with some leaning toward a preference for lighter or heavier doses.

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Molasses And Cannabis: Taking Your Soil To The Next Level

Hands-on grow room experience with a particular cannabis strain is really the only way to know for sure. Although, it must be noted that typically only the XL auto strains have a greater thirst for nutes. Most ruderalis hybrids are kind of like feeding miniature sativas, even if they have predominantly indica genetics.

Heavy feeding, or in other words full-strength doses of cannabis nutrients, accompanied by timely doses of bloom booster supplements can work wonder for yields. But only if you have a strain with a proven positive response to an intense feeding regime. Instead, try to adopt a feeding schedule with an objective of dosing nutrients to just the right amount.

Anyone that’s ever tried to “juice” bunko marijuana with boosters and potions can tell you that you’re wasting your time and money. Genetics will determine how potent and how much of a stash you bring to harvest. Even if you do everything just right, you can and likely will still hit the ceilings dictated by genetics. Work up your feeds slow and steady, monitoring plant behaviour every step of the way. Sorry, no shortcuts for this one.

Ph & Micronutrients

PH And Micronutrients

Macronutrients cover plants’ basic NPK requirements, but not everything. Micronutrients must also be blended into the cannabis feeding program. Plus, for any nutrients to be available to roots, the pH of the growing medium and the nutrient solution must be perfectly dialled-in.

Silica may well be classed as a cannabis macronutrient in the future, as it is all-important to plant health by thickening cell walls. Better still, silica has recently been linked to increased trichome production by North American professional growers.

Every name brand of nutrients has a host of supplements to cover all the micronutrients. These will be the products with the 0.1, 0.2, etc. NPK values. High-grade soil should contain most trace elements that cannabis needs. If not, you can always feed some molasses tea once a week.

It’s mostly coco and hydro growers that will require the vast majority of these products. A good sized bottle of Ca/Mg will be essential. Don’t forget pH of 5.5-6.0 for coco and hydro. 6.0-6.5 for soil. Dial these levels in for every feeding. Either invest in a pH meter or pH-perfect nutrients to make sure. Now get to work on that bumper crop.