Cannabis Fertilization Requirements at Each Stage of Growth

While your specific growing situation and especially your varieties will likely lead to adjustments in fertility inputs, these general guidelines have produced many successful cannabis crops. 

1. Seedling or Cutting

The plant can live for a time off of nutrients in the seed. Use minimal or no fertilizer in the early seedling stage. Rooted cuttings are often deficient after propagation. Feed both very gently with a 1-1-1 balanced formula at about 100 ppm for each once there is adequate root development.

2. Vegetative Growth

The vegetative growth stage averages 4 weeks, but can be as short as 2 weeks or as long as 2 months depending on environment, variety and container size. After transplant, kick feed rates up to about 200 ppm N, 120 ppm P₂O₅ and 200-250 ppm K₂O for vegetative growth. 

3. Early Bloom

4. Late Bloom

At week 5 of bloom, reduce N applications to about 125 ppm, and make sure you have adequate phosphorus once the calyx or sepals form.  Use about a 1 to 1.5 ratio of N to K₂O in the last four weeks of bloom. Potassium silicate may help strengthen plants during the latter part of the blooming cycle. 

5. Flush