Cannabis plants require nutrients during all phases of their growth. However, the way to provide nutrients is very specific, and you shouldn’t overburden your plants with too many nutrients all at once. Likewise, providing too little nutrients has adverse effects on the plant’s growth as well. Most growers use concentrated nutrients to more efficiently grow their plants.
Know that cannabis plants generally need three types of macronutrients – phosphorus, nitrogen, and potassium. These three are the foundation for healthy growth and high yields in cannabis plants. Despite this, plants need other nutrients and micronutrients like:
Generally, you can get these nutrients and micronutrients from your fertilizers, but there are differences between various fertilizers. The nutrient ratio can vary, and so can the ingredients used in the fertilizers. Some fertilizers are for soil, while other are for hydro mediums.
Nutrient requirements at each growth stage
- Cannabis seedlings only require feeding after 3-4 weeks, when they develop leaves. The NPK (nitrogen-phosphorus-potassium) ratio you should use is 2:1:2 (2N, 1P, 2K).
- Vegetative stage cannabis – By now, you’re using the 2:1: NPK Ratio, which is slowly adapting your seedlings to the nutrients. You might also want to use the 4:2:3 NPK Ratio for even better results in shorter timeframes. When the middle vegetative phase kicks in (6 weeks after germination), go with an aggressive 10:5:7 ratio to really increase the plants’ energy input. At the end of the vegetative state, you should lower the nitrogen input and opt out for the 7:7:7 NPK Ratio.
- Flowering stage cannabis – During the flowering stage, your cannabis will want more potassium for bigger flowers and more resin. For the first two weeks during the flowering stage, you should go with the 5:7:10 NPK Ratio, while the mid-flowering period matches the 6:10:15 ratio. More potassium for those babies! Finally, during the late-flowering period, go with the 4:7:10 NPK Ratio to soften things out.
It would be a good idea to know how to read the feed chart provided with all fertilizers. The manufacturers plan the fertilization for a set period of 12-13 weeks. You should fertilize the plants once a week and use a specific ratio of water as well (the feed chart will describe the process in more detail).
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How to fertilize your plants
Not knowing how to prepare the fertilizer and how to fertilize the plants can lead to severe damage. Here’s how you do it the right way:
- Prepare heated water (about 22°C).
- Add the nutrients and stir the mix. Also, use a PPM meter to be exact with your measurements.
- If you need to adjust the pH, use phosphoric acid or nitric acid.
- Feed the plants with the resulting mixture, and use the EC or the PPM meters to see if the plants are absorbing the nutrients properly.
If you don’t want to overfeed or underfeed your plants, using a PPM (parts-per-million) is a must. It measures the amount of nutrients in your mixture or the grow medium. If the plant soil contains nutrients, then only add the difference until you reach the recommended measurements on your feed chart. Both the temperature and the pH levels are very important if you want to grow your plants properly.
To optimize the fertilization process, you should learn more about these three procedures:
- Foliar feeding or foliar spraying – just spray the leaves to combat nutrient deficiencies and to provide key micronutrients during key growth stages.
- Chelation – Even artificial fertilizers contains chemical chelates that ease the nutrient absorption by the plant. Using organic chelates like humic or fulvic acid is even better when providing iron or zinc to your plants.
- pH flushes – flush your plants with pH-neutral water for the duration of an entire week before you harvest the plants. This way, the plants will absorb all remaining nutrients for a healthier and smoother smoke.
What about nutrient-related problems?
Nutrient-related issues are bound to appear even when veterans grow plants, let alone inexperienced growers. We’re talking about pH imbalances, which are caused by improper nutrient intake, water and medium imbalances. Nutrient burns are also problematic when the plants have too much nutrients to absorb. The plants may wither and die if this condition is left unabated. To treat it, just flush the plants with pH-neutral water.
Nutrient lockout issues manifest in the plant’s inability to absorb anymore nutrients. This is caused by pH imbalances or a nutrient build-up around the root. In turn, this problem leads to nutrient deficiencies, which leads to crispy and yellowed leaves, and various brown spots. You can flush with pH water and better control your fertilization procedures to solve this.
Are organic fertilizers better than chemical ones?
Naturally, using organic fertilizers is much healthier and promotes higher plant yields than chemical ones. The plant absorbs the nutrients in the soil much slower, which in turns prevents nutrient burn, nutrient lockout, and various feeding issues. Moreover, by using organic nutrients, you’re enriching the soil with plenty of microorganisms, creating a complex microbiome which benefits your plants in the long term.
Organic nutrients are more sustainable, they boost the health of the soil, and they’re eco-friendly, while chemical nutrients are incredibly accessible and easy to come by. Moreover, chemical fertilizers are absorbed much faster by the plant, but can also lead to nutrient burns and lockouts. Lastly, with chemical fertilizers, you have more control over the NPK ratio.
Whichever you’re using, it’s much better than simply letting your cannabis with no nutrients at all.