In vegg you want a higher N and a lower P K
But In Flower you’ll want a much lower N and a much higher P K
During the vegetative growing phase, plants need high nitrogen and potassium levels, and a medium intake of phosphorous. As a general rule, the amount of phosphorous should be around half of nitrogen, while potassium levels can vary from one-third to half of nitrogen. In the flowering stage, nitrogen level must be drastically lowered, while increasing phosphorous and maintaining the same level of potassium used in vegetative stage. All commercial cannabis fertilizers are differentiated for grow and bloom phases according to these basic principles.
Switching to the proper nutrient mix when plants start flowering just means feeding them with a different NPK balance. Nitrogen, phosphorous, and potassium percentages are indicated on product labels with three numbers, along the lines of NPK 5-18-5 – with each number indicating the ratio of N, P and K respectively. The correct proportions of the three main elements are calculated by the manufacturer. Therefore, the grower just has to add water and stick to the right dosage.
In addition to the NPK variable mix, cannabis actually needs small quantities of secondary and micronutrients. Some of these are more important than others for plant’s health. Most are already present in a good soil mix, while others are often included in cannabis feed in addition to NPK. Specialist additives can also be bought, but this is only advisable for more experienced growers, as overfeeding can be detrimental.