Feeding Cannabis: Nutrients & Feeding Schedule | Weedx

Feeding Cannabis: The Complete Guide for Every Growth Stage

Alongside light, water and climate, proper feeding is one of the most important factors for healthy cannabis plants and a good harvest. But when does your plant need which nutrients – and how do you avoid overfeeding? In this guide you’ll learn which nutrients cannabis needs at each stage, what a typical feeding schedule looks like and which mistakes you should avoid at all costs.

The basics apply to plants grown from seed as well as to rooted hemp clones.

Why feeding matters so much

For healthy growth and strong flower formation, cannabis plants need a balanced supply of macro, secondary and micronutrients. If you feed too little or too irregularly, nutrient deficiencies follow, usually showing up as yellow leaves and slower growth. If you feed too much, overfeeding or nutrient lockout can occur – this puts the plant under considerable stress and prevents dense, resinous flowers from developing.

The key nutrients at a glance

The NPK ratio on every bottle of fertiliser from the grow shop shows the share of the three main nutrients:

Nitrogen (N) – important for leaf and stem growth, especially needed in the vegetative phase
Phosphorus (P) – supports root development and is central to flower formation
Potassium (K) – strengthens the plant, aids energy transfer and improves flower quality

Cannabis also needs trace elements such as magnesium, calcium and iron so that all internal processes run smoothly.

Feeding by growth stage

Seedling stage

Young seedlings still draw their first energy from the seed itself and need hardly any additional nutrients. If you do feed, the mix should be very light, around a 1-1-1 ratio, so as not to overwhelm the delicate roots.

Vegetative stage

Now the focus is on building leaves and stems, so nitrogen demand rises significantly. Many growers use a ratio of around 10:5:7 in mid-veg, often switching to a more balanced ratio like 7:7:7 towards the end of the phase to prepare the plant for flowering.

Early to mid flowering

Once flowering starts, nitrogen demand drops while phosphorus and potassium become much more important to support flower formation. NPK ratios of around 1-4-3 to 1-5-4 are recommended in this phase; an N:P:K ratio of 1:3:2 is sometimes suggested as well.

Late flowering

In the last weeks before harvest, a pure potassium fertiliser (e.g. 0-0-10 or 0-0-20) can further support nutrient uptake and flower ripening. Important: no more fertiliser should be given in the last 1–2 weeks before harvest, so that no residues remain in the flowers – instead, flush with plain water only.

How often should you feed?

As a rough guide, fertiliser is usually given with every second or third watering. Many feeding schedules recommend regular application about every 10 days, increasing the dose from a low starting amount for seedlings to a higher dose during flowering.

pH and nutrient uptake

Even with optimal feeding, the plant can only absorb nutrients if the pH of the irrigation water is right. A pH of around 6.0–6.5 is considered ideal – if the value is much higher or lower, the availability of phosphorus, for example, is restricted, which can lead to growth problems.

Organic or mineral feeding?

Cannabis can be fed with classic liquid fertilisers as well as organic alternatives such as compost, worm castings or compost tea. Organic fertilisers also promote soil microbiology and provide a more even, gentler release of nutrients – however, the nutrients first have to be broken down by microorganisms before the plant can absorb them, so the effect is somewhat delayed.

Common feeding mistakes

Overfeeding – the most common cause of nutrient problems; when in doubt, dose more sparingly and watch the plant
Wrong NPK ratio at the wrong time – e.g. too much nitrogen still in the flowering phase
Ignoring pH – even a perfectly dosed fertiliser is of little use if it can’t be absorbed due to the wrong pH
Not flushing before harvest – affects the taste and quality of the buds
Irregular feeding – a fluctuating nutrient supply stresses the plant more than constant, moderate feeding

Conclusion

Proper feeding isn’t a matter of chance; it follows the plant’s natural needs at each growth stage: lots of nitrogen during growth, more phosphorus and potassium during flowering, and no fertiliser at all in the last weeks before harvest. If you also keep an eye on pH and dose a little too sparingly rather than too generously, you lay the foundation for strong plants and high-quality CBD flowers.

Sources

Note: this article is for general information about plant cultivation only. Please observe the laws on growing and possessing cannabis that apply in your country or canton.

Feeding Cannabis: Nutrients & Feeding Schedule at a Glance