Depends on a few decisions and variables
In several other articles on this web site and in the book we have outlined the three crucial variables (light, media, nutrition) and several other important variables (air, water, seeds, plant management) in successfully raising marijuana in an indoor environment. As should be obvious from these other articles, the best answer to the question “what should I feed my plants?” depends in part on the answers to these other variables. If you have decided to use a soilless media of Coco and Perlite mix, the answer to what and how should I feed my plants is straightforward. We have outlined in this article a great plan for feeding your plants.
If you are using soil or an organic mix like FFOC the answer is much more complex. The medium you will be using contains a lot of nutrients, so you will need to adjust the feeding formula to just cover the missing and consumed nutrients.
Feeding Cannabis Seedlings
For seedlings we recommended you use a modified Lucas grow formula mix using the “General Hydroponics” flora series nutrients and creating a mix of the three nutrient bottles in every gallon of water. This includes:
- 5 ml bloom mix
- 10 ml micro mix
- 15 ml grow mix
This mixture is very concentrated: up to 200 ppm nitrogen.
Because young seedlings are usually fed with a nitrogen level of 50 to 57 ppm, or about 25 to 33 percent of the real strength of the above mix, dilute one part of mix with 2-3 parts water for seedlings until leaves begin to show on the stem. After the seedlings begin to grow leaves the nitrogen strength can be increased up to 100 ppm, or dilute the mix with 1 part water for each part mix.
When the seedlings’ height reaches around 10 inches dilute the mix to 150 ppm, using 1 part water for 2 part mix. In this phase, observe your plant leaves keenly to make sure they do not show any signs of stress, and if they do move back to the weaker mix for a short period.
The Lucas Formula for Cannabis Vegetative growth stage
Once your seeds/plants reach the vegetative stage, the most straightforward approach to delivering a good mix of nutrients to your plants is represented by the “Lucas Formula” or “Lucas Ratio”. The “Lucas Ratio” outlines the best mix ratio of nutrients and micro-nutrients for the particular media you are using by creating a mix of “General Hydroponics” flora series nutrient building block system. Use the Lucas formula for seedlings from the time they are over 10 inches high until the seedlings have entered the vegetative phase of growth, which is identified by the plant having 5 sets of leaves. At that time switch to the Lucas vegetative formula which recommends: 10 ml bloom and 5 ml micro per gallon of water. This mix can be applied to the plants without diluting and without making them leggy or making the leaves burn.
Cannabis’ Flowering Phase
General Hydroponics Flora series feeding strategy is a sequence which follows a similar approach to the Lucas formula but includes an update for the blooming phase of plant growth. Using this update, the flowering should must include application using a mix with 16 ml of Bloom and 8 ml of Micro per gallon of water.
Be cautious with light feeders such as Kali mist and start feeding them with just half of the strength above to avoid burnt leaves.
General Hydroponics Nutrient System
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Feeding Formulas Summary
Remembering that the media you use may require adjustments to the nutrition formulas, the recommended formula for Coco media using Hydroponics Flora series nutrients is:
Seedlings: 5 ml bloom, 10 ml micro, 15 ml grow General Hydroponics Flora/Gallon H2O
*Dilute as recommended above for each seedling phase
Vegetative: 10 ml bloom and 5 ml micro General Hydroponics Flora/Gallon H2O
* Vegetative starts once 5 sets of leaves appear
Blooming: 16 ml of Bloom and 8 ml of Micro General Hydroponics Flora/Gal H2O