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What Are the Best Marijuana Fertilizers and Nutrients?


Currently, in the U.S., a majority of states have implemented legislation for medical and/or recreational (adult-use) cannabis. The rules and regulations of this legislation vary significantly across state governments. In California, individual consumers can cultivate marijuana plants, while in Missouri, one has to obtain a doctor’s certification and medical card to do so. Regardless of your state’s cultivation laws, if you can legally grow, you will need to learn about fertilizer and find the right product for your individual needs. 

Organic Marijuana Nutrients

Healthy marijuana plants require fertilizer with three elements for strong roots and high flower yields: nitrogen (N), phosphorus (P), and potassium (K). This combination of elements will often be represented on packaging as a single entity, NPK. So, if you’ve ever wondered what NPK stands for when nutrient shopping at your local grow store, now you know. Nitrogen is vital for leaf growth, potassium facilitates the development of flowers, and phosphorus contributes to root and bud growth. Together, these are the essential nutrients to grow weed.

However, NPK nutrients aren’t the only ingredients found in weed fertilizer. Marijuana plant food also contains micronutrients such as calcium, magnesium, sulfur, and several others. While these nutrients for growing weed aid specific growth processes, they are not as crucial as the three core nutrients, NPK, which are the best nutrients for growing weed. Let’s explore what each of these macronutrients provides the plant:


Nitrogen is essential to any organic lifeform on earth. Not only is it a vital factor for the chlorophyll production that spurs photosynthesis, but it’s an integral component of amino acids, which are the building blocks in all proteins. 

Cannabis plants require nitrogen throughout the entirety of their life cycle. Just as humans require adequate protein as an energy source to maintain healthy muscle mass, plants need it to form strong roots, stalks, branches, and leaves. Without sufficient nitrogen, cannabis plants will wither away and simply not be able to support growth. 

Spotting a nitrogen deficiency is relatively easy once you know what to look for. It’s common for leaves to turn yellow and fall off the plant. However, this is considered more normal for lower leaves as they are dying off to save energy for the tops of the plants to grow. Therefore, when the leaves receiving the most light at the top of the plant begin to yellow, it could signify a nitrogen deficiency.


The second of the NPK nutrients is phosphorus. This nutrient is responsible for strengthening a plant’s structure by creating strong roots and buds. It is also required for photosynthesis, metabolism, and the uptake of additional nutrients. Essentially, phosphorus helps a plant reach its fullest potential and achieve its genetic integrity. While necessary during the entire life cycle, phosphorus does its best work during the flowering stage. Cannabis plants with adequate phosphorus levels will be strong, sturdy, and vibrant with a solid root system. 

Without phosphorus, a plant cannot produce flowers and will likely be stunted in growth. Early signs of deficiency look like a reddish-purple color spreading throughout the leaf’s veins, and the leaves may begin to turn gray, blue, or a deep shade of green before eventually turning yellow and brittle. Additionally, plants with inadequate phosphorus levels are more susceptible to plant diseases and pests.


Potassium is kind of like the immune system of the plant. Cannabis demands extra doses of this valuable nutrient during its flowering phase to produce chunky, well-developed buds. In addition to increasing the size of the buds, potassium protects the plant from infection and disease, helps to use water efficiently, and strengthens plant tissue. 

Much like nitrogen and phosphorus, potassium is known as a mobile nutrient. This means it can be taken from old-growth and redirected towards the newer growth. This is why deficiencies will show on the oldest growth first, where the leaves will begin to yellow at the tips until they eventually turn brown and crumble. As a result, stems will weaken, and the overall yield will be much less than it would have been with proper nutrition.

Household Nutrients for Weed Plants

Before embarking on your quest to find the perfect cannabis fertilizer, you must first decide whether to utilize “homemade” nutrients or purchase products from a local gardening store. Of course, you can always make your own nutrient profile with your preferred mixture, but it is less complicated to buy pre-made nutrients. 

For example, a standard “homemade” plant food for weed might contain 4 parts cottonseed meal, 2 parts phosphate, 2 parts wood ash, 1 part limestone, and 1 part kelp meal, which would need to be purchased separately and mixed. However, the nutrients derived from these five substances can likely be bought as one nutrient-mixed product at the store. 

For beginning cultivators, purchasing pre-mixed fertilizer is the safest bet. As you become more experienced, you can experiment with different amounts of nutrients and make observations of your cannabis plants to determine your preferred mixtures. 

Fertilizer Guidance for Each Growth Stage

Choosing the best fertilizer for marijuana can be daunting for both the experienced cultivator and the novice. If you don’t use enough or have the wrong ingredients, your marijuana plants won’t grow to their full potential. However, if you use too much, your plants will likely develop “nutrient burn,” indicated by yellow, burnt tips on the leaves. 

While some slight variations may occur, there are some standardized guidelines for what your plants need during their early growth, vegetative stage, and flowering.  

Early Growth

Early growth is defined as seedlings or fresh cuttings. This is when your plants are just beginning to grow, reaching for light, and developing their fragile roots. During this time, the plants can easily thrive off of the nutrients from the seed and the minor amounts found in the peat plugs or potting soil. However, too much too soon will harm these young plants. Generally, do not start feeding plants until they have at least 2-3 true leaves. 

Vegetative Stage

The vegetative stage lasts anywhere from four to twelve weeks. During this time, your plants are going to require an NPK ratio of roughly 3:1:1. This ratio is defined as 3% nitrogen, 1% phosphorus, and 1% potassium. Keep in mind that the soil you are using is likely rich in nitrogen, so you may not necessarily want to feed with fertilizer at this exact NPK ratio. Because of this, you may want to use a 1:1:1 NPK fertilizer as a safety precaution. 

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Flowering Stage

The flowering stage is divided between early bloom and full bloom. The first sign of flowering is the development of pistils. During the early bloom stage, adjust the NPK ratio to 1:3:2. You’ll recall that phosphorus is critical during this time to strengthen the plant and develop strong roots and buds to support the mature plants. This adjustment prepares the plant to produce super dense, chunky buds bursting with trichomes. 

During late bloom, adjust the NPK ratio to 0:3:3. The plant will utilize the remaining nitrogen present, but its need for potassium increases. This is when anything that might go wrong with the plant could destroy the crop, and potassium helps ensure a healthy harvest with an optimum yield.

Keep in mind that these are generalized guidelines. When using commercial nutrients, be sure to follow the directions provided. Not all nutrients are created equal, and some products suggest a minor adjustment to ratios as often as every week. Be sure to keep a log of your plant care to include feeding schedules, ratios, and how the plants are responding to the nutrients. As you become more experienced with cultivation, you will begin to see which strains respond best to a particular fertilizer, and you’ll be able to quickly spot and treat deficiencies.

Cannabis Fertilizer to Nourish the Soil for Marijuana Plants  

Asking a room full of growers what is the best marijuana fertilizer will rile up the crowd just as much as asking if indoor or outdoor weed is better. 

When fertilizing cannabis plants, you focus on feeding the soil, not the plants. It’s the living soil that determines a plant’s success.
Yes, light and water are critical elements, but what goes into the soil will predict the outcome of the end product. 

If you’ve never heard of bokashi, your plants are missing out. Bokashi is fermented organic matter made by adding fermented bran, rice, or wheat to a compost collection. You can make this at home, but it can be a time-consuming and tedious process unless you enjoy home composting. TeraKashi is an organic bokashi fertilizer that you can buy online and add directly to your soil. By introducing antioxidants and minerals into the soil mix, TeraKashi breaks down nutrients that the plants cannot absorb, allowing them to grow bigger and produce higher yields. 

In addition to nutrients and minerals, plants need the valuable microorganisms found in soil. Sometimes, even pre-mixed potting soil doesn’t contain diverse compounds, and an additional supplement will be highly beneficial. Products like TeraGenix’s EM-1 do just that by increasing the number and diversity of microbes in the soil. This improves the soil structure and helps the nutrient cycling process and improves water absorption. 

Indoor vs. Outdoor Needs

Nutrient and fertilizer requirements vary based on growing conditions. For example, while indoor and outdoor cannabis needs supplementation, the exact formula may differ. If you choose to grow hydroponically indoors, you will need to up your nutrient feeding schedules because they are cycled much quicker than a soil system. 

Even when growing outdoors, nutrient needs vary depending on where you plant your pot. In the ground, containers, or raised beds all come with slightly different requirements. This is because of the diversity in soil drainage for different types of grow media. It’s important to know the percolation rate  of your soil to adjust your feed ratios accordingly. Fortunately, most store-bought fertilizers will provide an instructional guide where you can match up your grow media with your grow set up.

How Often Should I Feed My Weed Plants?

As soon as you begin feeding your plants in the vegetative stage, use a marijuana fertilizer every other time you water. Continue to follow directions as advised on the packaging to determine the proper ratios week over week. 

When your plants begin to flower, follow the same feeding schedule every other watering. But, be sure to adjust the ratios to accommodate the new growth cycle. 

Monitoring the trichomes on the plant will help you determine how close you are to harvest. This is when you prepare to flush. Flushing your plants is when you use only water to wash out any remaining nutrients in the soil. If you don’t flush your plants to rid the excess salts and nutrients, the final product can taste bitter and harsh to smoke. 

If you grow in soil, you’ll want to flush one to two weeks before harvest. If you use coco, flush within the last week. For all hydroponic grows, flushing is only necessary for one to two days before you harvest. 

Additional Readings on Cultivation

The Weed Blog is a comprehensive source to find reviews of specific top strains of cannabis and online news resources regarding the legalization of marijuana. We are committed to helping you find valuable information about cannabis on our website. With marijuana law constantly changing, learn about the latest legislation from our website and what you can do to help. Otherwise, consider these other top tier articles regarding cannabis cultivation:

How to Organize the Watering Process When Growing Marijuana

What You Need to Know about Autoflowering Cannabis Seeds

What Budget Do You Need for Growing Marijuana at Home?


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