Nutrients are a major part of your cannabis plants' lives. They are essential to their health and well being, and you are going to have to make sure they are getting just what they need in order to thrive. The three main nutrients are nitrogen, phosphorous and potassium – or NPK for short. For a better understanding of exactly what these nutrients do to your cannabis plants, see our article on Nutrients for Cannabis Plants.

NPK can be obtained for your cannabis with a few methods. These are through the soil mix you may use a growth medium, compost and fertilizers (often in liquid form). The quantity of each nutrient is often displayed on the packaging of the product (for shop bought items). This quantity is expressed as a ratio, for example 20:20:20; what this means is that the mixture you have bought consists of 20% N, 20% P and 20% K. The remaining 40% will be made up of soil or water etc depending on what you have bought. This ratio is likely to vary brand to brand, so make sure to read the label.

The stage of growth your cannabis plants are in is going to largely dictate how much of each nutrient they need.

Germination and seedling stage

Do not add any additional nutrients in during this stage unless you are 100% sure you know what you are doing. Young cannabis seeds are very vulnerable to overfeeding. It is recommended to buy a dedicated germination soil for this stage and add nothing else.

Vegetative stage

During this stage your cannabis plants are going to require high levels of nitrogen (N) and moderate levels of both phosphorous (P) and Potassium (K). You will need a grow medium mix that has a higher or equal ratio of N to P and K – for example 12:12:12 or 12:6:6.

Flowering stage

Once your marijuana plants have reached the point where they start to flower, they are going to need a higher amount of phosphorus (P). Be ready to adjust the balance of your grow medium accordingly.

The amount of nutrients required can vary strain to strain. For example, a strain that does not need too much feeding will be fine in a 10:10:10 grow medium, whereas a strain that is nutrient hungry may require a 20:20:20 substrate. Notice here, the effective ratios of nutrients are the same in relation each other, but the latter example has a higher overall content.

Giving your cannabis plants too much or too little of any nutrient can lead to problems. It can be very easy for a novice weed grower to get it wrong and over/underfeed their plant. With time, you will get to know what each strain you grow requires from you, but until then it is a good idea to have a look at our articles on how to feed your plants, as well as our troubleshooting article - which tells you what bad signs to look out for, what may be causing them and how to remedy them.