Depending on your type of grow, choosing the best fertilizer for marijuana plants can make a real difference to both the size and quality of your yield. Trouble is, the market for cannabis fertilizer is pretty saturated. What nutrients does your cannabis grow need? In what concentration? What are the best brands? Is it better to spend more on marijuana fertilizer, or can you get what you need without breaking the bank? We have narrowed down the most popular and well-renowned nutrients to make your choice a little easier. After all, a well-fed cannabis plant is a happy and productive cannabis plant.
Marijuana plants need a balanced diet. From all the essential macro and micronutrients to N-P-K ratios suitable for different growth stages, your plant needs the right nutes in the right volume at the right times.
The Best Fertilizer for Marijuana Grown in Soil
Organic soil is teeming with beneficial microorganisms. These microbes feed off plant waste, and can produce ready-to-use nutrients that your plant will use to grow. You can take advantage of this symbiotic relationship by complementing it with organic nutrients. You can read more on the ideal feeding schedule for soil and more articles relating to nutrients and fertilizer.
Note: If you are using super soil or living soil, there is usually no need to add nutrients or fertilizers throughout the grow.
1. Pure Blend Pro Bloom Soil by Botanicare
NPK Ratio: 1-4-5
Ideal for: Flowering stage
Botanicare is a leading hydroponic brand that has been in the market for nearly thirty years. They sell products formulated explicitly for soil, such as Pure Blend Pro Bloom Soil. It belongs to the best-selling Pure Blend Pro Series – a line of marijuana fertilizer consisting only of natural and organic-based ingredients like fishmeal, seabird guano and kelp. As with any Botanicare nutrient products, you do not have to worry that you’re feeding your cannabis anything toxic.
Pure Blend Pro Bloom Soil contains the essential major and secondary elements that cannabis needs, including calcium and magnesium, as well as some trace minerals. The high amounts of phosphorus, in particular, make it ideal for blooming marijuana plants. It comes in a water-soluble formula that promotes rapid nutrient absorption.
2. Soil Liquid Trio Pack by FoxFarm
NPK Ratio: 6-4-4 (Grow Big), 0-0.5-0.7 (Big Bloom), 2-8-4 (Tiger Bloom)
Ideal for: Vegetative stage (Grow Big) and flowering stage (Big Bloom and Tiger Bloom)
FoxFarm is already a household name for top-notch soil mixes and fertilizer for marijuana plants – and unsurprisingly so. The company, after all, takes pride in quality and consistency, delivering only reliable, tried-and-tested formulations every single time.
Soil Liquid Trio Pack is among their most famous creations. This three-product collection brings together some of the highest-selling FoxFarm liquid weed fertilizer – Grow Big, Big Bloom, and Tiger Bloom. This powerful trio encourages healthy, robust growth and prolific bud development. When paired with soil that has been enriched with beneficial microbes, worm castings and bat guano, expect explosive growth and yields unlike any other.
3. Flower Girl Bud & Bloom Booster by Dr. Earth
NPK Ratio: 3-9-4
Ideal for: Flowering stage
Since its inception nearly three decades ago, Dr. Earth has been committed to clean and healthy gardening. In line with this vision, their products contain only sustainably-sourced natural and organic ingredients. Flower Girl Bud & Bloom Booster – a dry and fast-release fertilizer – is no exception. This potent blend features alfalfa meal, feather meal, fishbone meal, soil microbes, mycorrhizae and mined minerals. It encourages vigorous budding and can be used as a stand-alone supplement during the bloom stage.
Best Fertilizer for Marijuana Grown with Hydroponics
As the name indicates, soilless media – such as peat, hydroton, rockwool, coco coir, perlite and vermiculite – do not contain soil. Some, though, might look or even feel like soil. Unlike soil, however, these substrates are usually inert – or lack nutrients and/or beneficial microorganisms. This means you’ll have to nourish the plants from the very beginning.
Soilless growing media can either be used for hydroponic systems – such as deep water culture, nutrient film technique and ebb and flow – or soilless growing. All the products below are compatible with both, read on, and decided which is the best fertilizer for weed grown in your hydroponics setup.
Note: If you have a hydro setup, consider increasing the carbon dioxide concentration in the room to help boost plant growth. One way of doing this is by using white vinegar and baking soda.
1. Kind Nutrient System by Botanicare
NPK Ratio: 2-2-4 (Kind Grow), 4-0-0 (Kind Base), and 0-6-6 (Kind Bloom)
Ideal for: Vegetative and flowering stages
The Kind Nutrient System – featuring Kind Grow, Kind Base and Kind Bloom – is a top-quality hydro cannabis fertilizer from Botanicare. This series highlights the brand’s patented formula, which is packed with powerful nutrients and carefully chosen supplements. Together, the three products fulfill the requirements of cannabis plants during all stages of growth.
The Kind system also gives you full control over the cultivation process. In particular, it allows you to easily customize the blends to meet specific needs – be it maximum root development, lush foliage, accelerated growth, or enhanced yields. Attaining your desired harvest has never been so easy.
2. Flora Series by General Hydroponics
NPK Ratio: 2-1-6 (FloraGro), 5-0-1 (FloraMicro), and 0-5-4 (FloraBloom)
Ideal for: Vegetative and flowering stages
You have probably already heard of General Hydroponics – they’ve been a mainstay of the hydroponics industry for more than forty years.
One of their highly-acclaimed types of marijuana fertilizer is the Flora Series, which consists of FloraGro, FloraMicro, and FloraBloom. Each product is formulated to satisfy the requirements of cannabis plants across different phases of growth. You can also combine the products to obtain the precise nutrient ratios you need. Either way, you can be assured the crops will receive the optimal balance of all the nutrients, allowing them to develop to their fullest potential.
3. FloraDuo by General Hydroponics
NPK Ratio: 5-0-6 (FloraDuo A) and 1-5-4 (FloraDuo B)
Ideal for: Vegetative and flowering stages
FloraDuo is yet another gem from General Hydroponics. This innovative nutrient system comes in two parts – FloraDuo A for vegetative growth, and FloraDuo B for blooming. It promises cannabis plants their much-needed primary, secondary and micro nutrients in every growth stage. It’s incredibly flexible, allowing growers to tweak the nutrient mix and ratio as the crops mature and transition through their phases.
Best Fertilizer for Weed Plants Grown in Coco Coir
Coco coir, which is made from fibrous coconut husks, is among the most popular soilless media for cannabis growers. Since it’s perfectly suitable for hydroponics, the hydro fertilizers listed above can be used for coco as well. Although you will have to supplement with calcium and magnesium to prevent nutrient deficiencies later in the grow.
1. CALiMAGic by General Hydroponics
CALiMAGic is an ultra-concentrated blend that contains fully soluble and readily available calcium and magnesium. If you are using a hydro setup, it won’t clog spray lines or drip emitters. It can easily be mixed with fertilizers and is aimed for crops that need higher levels of calcium and magnesium than usual. That includes cannabis plants grown in coco. Simply put, CALiMAGic can make any hydro marijuana fertilizer viable for coco coir, helping to optimize plant nutrition while avoiding nutrient problems down the road.
2. Cal-Mag Plus by Botanicare
Cal-Mag Plus is developed to make up for any mineral deficiencies in a nutrient program – such as coco coir’s natural tendency to lack calcium and magnesium. This supplement is also enriched with nitrogen, iron and other trace minerals to help maximize yields. When used alongside nutrient mixes, this blend boosts the plant’s absorption of essential minerals. For best results, pair it with Botanicare fertilizers.
3. Coco A & B by CANNA
NPK Ratios: 4-0-1 (Coco A) and 0-4-2 (Coco B)
Ideal for: Vegetative and flowering stages
CANNA is a Dutch company selling innovative and high-quality growing media, fertilizers, and supplements. Their products are a breeze to use, allowing even the most inexperienced of growers to reap a spectacular harvest.
Coco A & B belongs to the brand’s line of coco cultivation products. This fertilizer pack consists of two products – Coco A for growing, and Coco B for flowering – and contains all the essential elements that cannabis plants need. Aside from minerals, it’s also packed with natural chelates, humic acid, and fulvic acid for maximum nutrient uptake. Both products were also formulated with the unique properties of coco coir in mind. This duo not only nourishes your crops, but also helps you make the most out of your substrate.
Bonus: The Best Natural Fertilizer for Marijuana Plants
If you are growing in soil and do not want to shell out for commercial blends, then consider making one yourself. These are different types of homemade marijuana fertilizer and they typically contain natural and organic ingredients. Each material has its corresponding nutrient content, and you can experiment to attain the desired nutrient ratio.
|Organic Material||Nutrient Content|
|Compost||Nitrogen, phosphorus, potassium|
|Worm castings||Nitrogen, nitrates, potassium, phosphorus, and calcium|
|Chicken manure||Nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium|
|Bone meal||Nitrogen, phosphorus, calcium|
|Bat guano||Nitrogen, phosphorus, potassium|
|Kelp meal||Nitrogen, potassium|
|Garden lime||Calcium and magnesium|
|Gypsum||Sulfur and calcium|
Unknown to many, human urine is packed with nitrogen, which is one of the critical nutrients for healthy cannabis growth. Depending on the diet, it may also contain small amounts of phosphorus and potassium. Make sure not to dump your pee directly on the plants, though. Instead, dilute it to a 1:10 ratio in water. Use immediately to avoid the formation of toxic ammonia.
Also called “black gold,” compost simply refers to decayed organic matter. To make, allow a damp pile of organic materials to decompose over a period, which can take anywhere between three months to two years. It is not only rich in nitrogen, phosphorus and potassium but it contains micronutrients and trace minerals as well. It can be prepared as compost tea and used as a foliar spray.
Simply known as worm manure, worm castings are what the earthworms release after feeding on soil microbes and other organic matter. They hold a wide range of minerals, including nitrogen and nitrates. It is a potent cannabis fertilizer, so a little goes a long way. The recommended casting to soil ratio is 1:4 or 1:5.
This material consists of chicken manure and urine. Of all the animal feces, it contains the highest amounts of nitrogen, phosphorus and potassium. It’s also packed with micronutrients. It is usually composted for 6 to 9 months before use to make it less “hot” for the plants. To use, dust it over the soil bed or work it into the soil.
This powder is a slaughterhouse byproduct and consists of dried and crushed animal blood. It is one of the richest sources of organic, non-synthetic nitrogen in the market. It is incredibly potent and should be used sparingly.
This fine powder is made of ground animal bones – usually that of cattle, hogs and other animals from meatpacking plants. It’s an excellent source of phosphorus and calcium. It also has small amounts of nitrogen.
This material, consisting of bat droppings and urine, has been used as a fertilizer for thousands of years. It typically has a 9-6-2 or 10-3-1 NPK ratio. It also contains trace amounts of macronutrients. You can work it into the soil or prepare it as compost tea. Read our article Is Bat Guano Good for Weed Plants? for further information on this organic marijuana fertilizer.
This marine-based ingredient consists of dried and ground seaweed. It usually has a 1-0-8 NPK ratio and boasts more than sixty different essential minerals.
Also called dolomite or sweet lime, this alkaline material is often used to raise the soil pH. It contains decent amounts of calcium and magnesium.
Also known as calcium sulfate, gypsum is a naturally occurring mineral that is mined from sedimentary deposits. It is an excellent source of calcium and sulfur.
This table salt-like material is another naturally occurring mineral. It is prized for its high magnesium content. To use, dissolve about one to two tablespoons of the salts in 5 liters of water. The solution can be directly added to soil or used as a foliar spray.
This is, simply, the leftover powder from burning wood – such as the ashes from a fireplace – it’s a fantastic source of potassium. Moreover, it helps increase the pH level, making it ideal for areas with over-acidic soil. To use, sprinkle it on the plants or add it to the compost pile.
Things to Consider When Choosing Cannabis Fertilizers
There are so many factors to keep in mind when deciding on which marijuana fertilizer to use. Understanding them allows you to choose which one best suits your needs. If you are confused, do not fret. This section will help you navigate your way across the countless options in the market – and make the right choice.
Soil vs. Hydro
First, consider the growing method – is it soil or hydro?
It’s important to choose a product that caters to your gardening situation. If using soilless media – whether you intend to plant in pots or install a hydro system – opt only for hydroponic fertilizers. Similarly, if using soil, stick to what is designed for your needs. Note, though, that some are compatible with all growing styles – be it soil, coco, or hydro.
Homemade vs. Professional
If you are growing in soil, you can choose between a homemade cannabis fertilizer or a professional blend.
To prepare homemade nutrients, you need to combine organic matter sourced from minerals, animals and plants. You do have to be mindful of the ingredients you add, ensuring you achieve the optimal nutrient ratio for your plants. You will have to experiment – and possibly make mistakes along the way. It can be labor-intensive, but it allows you to customize everything to match your needs and preferences. This do-it-yourself option is better suited for advanced growers.
For many, buying professional fertilizers is a lot simpler. Since the blends already have known ratios and formulations, there is no need to tinker with different mixes, which means less risk of mis-feeding your plants. These products are ready-to-use and may contain natural or synthetic ingredients.
Note: If you have a hydro setup or are growing in soilless media, you need to buy professional fertilizers that are made especially for hydroponics. These usually do not contain organic matter.
Take into account the current growth stage of the plants. Remember, the nutrient requirements of cannabis increases as it matures, decreasing only in the late flowering stage. Make sure the NPK ratio is appropriate. As a guide, refer to the table below.
|Growth Stage||Nitrogen (N)||Phosphorus (P)||Potassium (K)|
|Flowering||Low||Medium to High||High|
Note: Steer clear of “slow-release” or “extended” fertilizers, which release a steady stream of nutrients over a period. Such products can cause nutrient problems later on.
Choose the Best fertilizer for Marijuana Plants to Stay Healthy
Choosing which weed fertilizer to use can be a hurdle for many cannabis growers, especially those who are just starting out. Aside from never-ending options in the market, there are also different types available. How on earth do you even know which one is for you?
There are many considerations. Ultimately, it boils down to the growing style and the current growth stage of the plants. Make sure you opt for a fertilizer designed for your needs. And, if using soil, you also have the option to go down the do-it-yourself route.
Using high-quality, tried-and-tested marijuana fertilizer, though, is just one step. To keep the plants healthy and thriving, you also need to have a basic understanding of cannabis nutrition, as well as the right feeding and watering practices.