Growing cannabis outdoors has incredible potential to yield ginormous, terpene-laden crops — if the plant’s nutritional needs at each stage of development are met. Below, we present you with the ultimate, completely optimized outdoor grow nutrient plan for maximum plant wellness, explosive growth, and resin production. Whether you’re a seasoned grower or a beginner, this nutrient regimen is formulated to see your outdoor grow nutrient schedule by precisely matching nutrient input with every growth phase.
Learning About Outdoor Cannabis Nutrient Requirements
Outdoor cultivation adds factors that indoor cultivators cannot closely control, such as soil blend, climate, and the microbial flora in the atmosphere. Because of this, a disciplined but flexible nutrient program is necessary. Cannabis crops require varying ratios of macronutrients — nitrogen (N), phosphorus (P), and potassium (K)—and secondary nutrients like calcium and magnesium, as well as a range of micronutrients, to develop.
Environmental factors such as wind, rain, soil variability, and natural pests may favor or deter nutrient uptake. An outdoor crop in good health must possess a solid nutrient uptake system supported by strong root health and good soil biology. Regional factors such as temperature swings, day length, and humidity also impact the rate at which nutrients are broken down. Optimizing nutrition to fit outdoor environments is crucial to being resilient and reaching maximum yield.
When to Start Giving Seedlings Nutrients
1. Seedling Stage (Weeks 0–3): Building a Healthy Foundation
Less is better at the seedling stage. Young seedlings can be hurt by too much feeding, resulting in nutrient burn, stunted growth, and root damage. During this stage, the plant’s root system is still developing, and an excess of nutrients can overwhelm its ability to process them, typically resulting in irreparable damage. A light touch enables the seedling to build a healthy foundation without being poisoned by nutrient toxicity.
- Nutrient Focus: Minimal feeding cannabis. When working with high-quality soil, water-only methods are ideal. This enables seedlings to adjust to the natural nutrient level of the soil without overloading them. Light organic additives such as worm castings or kelp extracts can be added if the soil is deficient in essential micronutrients.
- Feeding Frequency: Light once-weekly foliar sprays or weak root feeding after true leaves have emerged. Novice growers often like to skip adding nutrients to the potting soil initially, since it can overwater or overfertilize and be stressful to sensitive seedlings.
While seedlings are very sensitive to excess nutrients, they do enjoy microbial inoculants that promote root health. These inoculants can be introduced early to help the seedling build a strong root system, which will be necessary for nutrient uptake in later stages of growth.
2. Vegetative Stage (Weeks 4–10): Green Explosive Growth
Vegetative is when outdoor cannabis plants feed for their future heavy loads of buds. The maximum leaf weight now will directly affect flower size in the future. Plants are in a stage of maximum growth at this time, with leaves increasing in size to catch as much light as possible, with stems and branches growing in preparation to support the heavy buds that will come with the flowering stage.
- Nutrient Accent: Excess nitrogen intake triggers vegetative growth. Nitrogen helps in the formation of chlorophyll and promotes the development of robust, healthy leaves. Leaves act like the solar panels of the plant, powering all metabolic processes.
- Recommended Nutrient Feeding: To attain maximum growth, nitrogen needs to be supplied in higher concentrations during the early to mid-vegetative stages. Organic nitrogen sources like blood meal or alfalfa meal can be used in soil, while liquid fertilizers are the ones that ensure more immediate delivery of nutrients. Supplementing phosphorus and potassium in moderate amounts further will ensure the root of the plant grows healthy and facilitate early flower formation.
- Feeding Frequency: 5–7 days through soil drench; foliar feed every 10–14 days using a nitrogen-based spray. Overfeeding is still to be avoided, but the nutrients being supplied are to be tweaked to provide a balance between quick growth and structural support.
As the plants grow, their nutrient needs shift, and constant checks must be made to avoid nutrient imbalance. In this case, a slight increase in potassium gives the plants the energy to support their developing leaves and future flowers. Plants also gain from being treated with silica products that help strengthen cell walls, improving the plant’s resistance to stress, pests, and diseases.
3. Transition Phase (Pre-Flowering Weeks 11–12): Bud Set Preparation
Transition to pre-flowering involves a marijuana plant’s nutrients adjustment to allow for the hormonal change that results in flowering. The aim is to gradually reduce nitrogen while adding phosphorus and potassium to prepare the plant for bud development.
- Nutrient Focus: Balanced NPK with a special emphasis on P and K. Phosphorus assists in root development and flower formation, and potassium assists in cell enlargement and plant overall strength. Cutting back on nitrogen at this time will keep the plant from forcing vegetative growth at the expense of flowering.
- Recommended Feeding: Transition the ratio of nitrogen to phosphorus and potassium over a period, using nutrient ratios favoring flowering first. Bat guano or fish bone meal organic amendments are rich in slow-release phosphorus, which will support this conversion.
- Frequency of Feeding: Nutrient application needs to be spaced further apart when the plant is in the pre-flowering stage. Foliar sprays with bloom enhancers that have added phosphorus can help support the plant when it’s in the flowering stage.
This flowering stage is a sensitive phase because poor nutrient management may result in lockout of the nutrients, and this implies that the plant cannot uptake the required nutrients to induce flowering. Through the proper application of phosphorus and potassium, you set the stage for a successful flowering cycle.
4. Flowering Stage (Weeks 13–20): Bulk, Density, and Resin Production
During flowering, the plant transforms, requiring the nutrient cycle to adjust to its new priorities. This stage is where marijuana plants will focus their energy on growing large, sticky buds.
- Early Flower (Weeks 13–15): Early flowering indicates the beginning of bud development, where phosphorus is especially useful for root well-being and establishing bud sites. Potassium helps plants create thick, hardy stems capable of holding larger buds. Nitrogen must be reduced at this stage to avoid excessive vegetative growth.
- Mid Bloom (Weeks 16–17): At this stage, the plants begin to focus on bud development, and the nutrition regimen must have potassium and phosphorus as its priority to enhance the development of heavy, quality buds. Micronutrients like manganese and zinc play key roles in enhancing resin development and cannabinoid level. The frequent application of bloom boosters containing additional phosphorus and potassium is also applicable for enhancing flower size.
- Late Flower (Weeks 18–20): When the plant reaches maturity, nutrients have to be gradually reduced. Excessive fertilizing during this stage will lead to nutrient toxicity and a bitter flavor. A water flush or light compost tea at this stage will eliminate residual nutrients, creating a cleaner, smoother smoke.
5. Flushing and Harvest Preparation (Weeks 21–22)
Flushing washes excess nutrients out of plant material, creating cleaner, smoother smoke and more potent terpene profiles. Flushing the plants ensures the final product is as good as it can be, free of any unwanted chemical residue and heavy salts that will affect the flavor.
- Flushing Time: Flushing would work best in the last 10–14 days from harvest. In this flushing period of the plant, the nutrients present are flushed out of the plant’s system, and then the plant begins to focus all its energy on ripening the flowers. The plant itself slowly tends to break down the stored nutrients towards maturity.
- Method: Immerse the soil in pH-balanced water (6.0–6.5) to encourage runoff, which can wash away excess salts and nutrients from the growing medium of the plant. Organic farmers can use a mild organic tea flush, providing beneficial microbes to break down any residual nutrients present.
Flushing is a critical part of the harvest preparation stage and is crucial in allowing the cannabis plants to finish their growth cycle with the best flavor, potency, and smoothness.
Pro Tips for Outdoor Cannabis Nutrient Schedule Success
- Soil Testing: Always test soil pH and nutrient levels at least twice a season to modify feedings cannabis as a result. This guarantees your plants get the right proportions of nutrients by the individual soil chemistry.
- Weather Adaptation: Heavy rains can leach nutrients from the soil, making them unavailable to your plants. After a storm, topdress with slow-release organic fertilizers or foliar sprays to replenish any lost nutrients.
- Organic Inputs: Organic soil inputs such as compost, worm castings, and alfalfa meal contain slow-release organic nutrients that take longer to release, reducing the risk of nutrient burn. Organic nutrients promote a healthy earth ecosystem that guards soil life as well.
- Preventative Measures: Apply silica on a regular basis, as it constructs fortifications in cell walls that also shield plants from pest and disease pressure and natural stressors like wind and excessive rains.
