How to Pick the Best Fertilizer for Cannabis

Fertilizer for marijuana plants

Growing your own cannabis can be a rewarding experience. With a little care and attention, you will have a reliable supply of healthy buds. But this is best achieved by getting the right fertilizer for your marijuana plants.

So what is the best fertilizer for weed? This area can often be a little confusing. There are so many options for you to choose from. But which one will be the best fertilizer for marijuana and offer the best performance?

Organic vs Synthetic

The first thing to consider is the type of fertilizer that you are getting. The two main types being synthetic or organic, while the third option is hybrid.

Synthetic Fertilizer

These are designed to give plants what they need to grow. This can be determined by looking at the NPK ratio. NPK tells you the precise amount of Nitrogen (N), Phosphorous (P), and Potassium (K) in the mixture. There might be a few other secondary, and micronutrients included with the mixture as well, for added benefits.

One of the downsides of synthetic fertilizers is how the product acts in the soil. These nutrients don’t typically contribute much to the overall soil composition. They are often applied to supplement the plant directly and be taken up either by the roots or through foliar application.  Because of this, the plant certainly may benefit in the short-term, but the soil typically gains no benefit from its application, meaning you will need to re-apply more in the near future.

On the positive side, synthetic nutrients are specifically designed to give the plants the nutrients they need to achieve strong growth. This can be tailored to suit the stage of growth that the plant is in. We’ll discuss what you should be looking for.

Organic Fertilizer

Using an organic fertilizer has a number of benefits over synthetic fertilizers. However, the main benefit is the improvement of soil health and biology by adding organic materials. This provides a more balanced environment for your cannabis plants to grow and thrive in.  Organic fertilizers also have a much lower risk of burning your plants with over-fertilization.  Since you are focused on feeding the soil primarily, the plant is not being force-fed nutrients; but rather being allowed to take them up naturally to encourage balanced growth during important stages of its life.

Hybrid Fertilizer

Hybrid fertilizers are an excellent compromise between synthetics and organic products.  Offering many of the benefits of both products, hybrids will often start with an organic base to provide the soil nutrition you desire, while be supplementing with synthetic components to provide a more immediate feeding to the plant. This is usually done to encourage a more direct, accelerated growth boost to the plant.  

Depending on the product, this can mean denser foliage, flowering, etc. So if you are not completely dedicated to organic products, you can certainly consider a hybrid product to give you the best of your fertilizer options.  If this is the direction you are headed, check out our hybrid (boost) line of fertilizers to get you going.

Best Type of fertilizer  to Use for Cannabis

In most cases, it will be easier to use an organic or a hybrid fertilizer for your marijuana plant. Not unlike synthetics, you will be able to get the mix of nutrients that you need, tailored to suit the stage of growth that the plant is in.  The benefit of organic/hybrid being that there is lower risk of burn when applying the fertilizer.

Finding the best nutrients for weed can be tough, but our organic and hybrid products are great options for either choice of marijuana fertilizers.  Follow the recommendations and you should see great results without a ton of experience or know-how necessary.  

NPK Requirements

There are a few distinct growth stages that you will go through when growing cannabis plants. At each of these times, you may consider fertilizer tailored to that stage of the growth cycle.


During this period, there is no need for any fertilizer. All you need to do is water the seedlings frequently, or apply a rooting product like our Azospirillum super concentrate to help with root development.

Vegetative Stage

This is often considered to be the stage beginning when plants getting their first leaves, to getting their first buds. It typically occurs several weeks after planting.  During this period, you want to get them the nutrients they require to make strong roots as well as encourage some vegetative growth and branching. Ideally, the NPK tailored to this period has a greater Nitrogen than phosphate or potash. During this time, something like Mr. B’s Green Trees Organic Growth 7-4-4 or Growth Boost 15-5-5 would be an excellent choice to maximize growth.

Transition Stage

As plants transition from vegetative cycle to flowering, the nutrient needs change along with it. The ratio of nutrients needed shifts from a higher nitrogen component to a more balanced ratio between the NPK as the plant prepares for bud and stem development. Switching to an all purpose blend (5-5-5 or 8-8-8,) works great, or you could go straight to the bloom specific products at this time as well.

Budding Stage

During this stage, you will need to again change the NPK ratios slightly. At this stage, nitrogen is consumed less and we can focus more on your phosphorous and potassium levels to maximize our yields. Some independent studies have shown high levels of nitrogen to negatively impact plant blooms because of this, something with an NPK ratio similar to that of Mr. B’s Green Trees Organic Bloom 2-8-6 or Mr. B’s Bloom Boost 2-10-10 will maintain that healthy flowering you are looking for to maximize your harvest.

Knowing the Right Amount of Fertilizer to Use

Now that we know the right type of fertilizer, it’s time to think about how much fertilizer you should be employing. Fertilizers will come with application instructions printed on the label.  You can use this to determine the ideal method of application for your plants as well as how much to use and how often. We also offer a great, easy to use calculator on our website that will allow you to calculate the exact needs of your garden in seconds!

Signs of Nutrient deficiency

Let’s start by looking at some of the signs you need to increase the nutrient load. Some of the most common issues you might observe include:

· Yellowing of leaves

· Death of plant tissue

· Low flower production

There are a number of reasons why a plant may lose it’s color. One of those reasons can be a lack of chlorophyll production; caused by nutrient deficiencies in the plant or soil.

If you’ve narrowed down the cause of the discoloration to a nutrient deficiency, you could do a soil test to find the specific nutrient you need to supplement, or you can try applying an all-purpose organic fertilizer in the meantime to bring some balance back to the soil.

Signs of Too Many Nutrients (nutrient burn)

It’s also possible to give your plants too many nutrients. More common to the growth stage, and also with synthetic fertilizer usage; this can lead to burning the plants. Burn will reduce the productivity of your cannabis crops and may kill off your plant altogether. There are a few signs that this might be happening, including:

· Wilting/curling

· Browning on edges of leaves

· Lack of plant growth

· Leaves falling off prematurely

Finding Nutrients

Applying the fertilizer is important. But you also need to make sure that you are getting a high-quality mix. There are plenty on the market, but you need a thoughtful formulation designed to give your plants what they require to grow strong buds. This is why so many people choose to use NorCal Nutrients. We understand what cannabis plants require at every stage of their growth and will provide the right mix of nutrients to feed the plant appropriately without negatively impacting the soil ecology.

If you are interested in purchasing one of these specialty fertilizers for your plants, you can find a dealer on our where to buy page.