What Are The Best Nutrients For Growing & Flowering Cannabis? Buyers Guide To The Top Soil & Hydroponic Liquid Fertilizers

Are you thinking about growing your own cannabis plants but getting overwhelmed as to where you should start? There are so many different products available for plants. It's not always easy to know which will be the best nutrients for cannabis.

Do you go with soil and organic nutrients or should you opt for hydroponic? Let me share my experiences with you, and show you what some of the options are. This can help you decide which nutrients you need. I’ll also share some of my favorite products, to make choosing easier.

What Nutrients Do Cannabis Plants Need?

cannabis nutrients

The answer to this question isn’t as simple as listing a load of individual nutrients that your plants need. Growing weed requires different ratios of nutrients at different times during the growing process. Then there's the question of whether you are growing your plants in soil or another medium, called hydroponics.

Let’s start with the various nutrients that they will need if you are using soil as your growing medium.

Best Cannabis Nutrients for Soil

Even at the simplest level, cannabis plants need over a dozen nutrients for healthy growth. These can be split into two different groups, referred to as macronutrients and micronutrients.

The most important nutrients obtained from soil are called macronutrients, and include:

  • Phosphorus
  • Nitrogen
  • Potassium
  • Magnesium
  • Sulfur
  • Calcium

The other basic building blocks which all plants need are oxygen, hydrogen and carbon, all of which they get from air and water.

The three most important of the nutrients I have listed above are nitrogen, phosphorus and potassium—chemically denoted as N, P and K.

When you buy nutrients or soil from the store, you might notice ratios on the packaging, listed as N-P-K. The exact ratios your plants need will change throughout their growth cycle.

During the vegetative state, before flowers start to bloom, a high level of nitrogen, medium level of phosphorus and high level of potassium are ideal. This equates to a 3-1-2 ratio of N-P-K during the first few weeks.

If you have chosen a good quality soil, additional nutrients might not be needed until the plants are over four weeks old.

Once your little beauties start flowering, then the amount of nitrogen can be reduced. I find a 1-2-3 ratio is ideal at this stage, to encourage large buds. Too much nitrogen can mean smaller buds and sometimes an unpleasant taste to the finished product. See FAQs below for a little more information.

Check the mix in your nutrients at this flowering stage. They should have low nitrogen and medium to high phosphorus to help produce more flowers, and high potassium to boost yield.

The other thing you need to check is the pH level of the soil. In general, soil regulates its own pH at about a level of 6.0 to 7.0. If your plants are not thriving, despite being fed with nutrients, check the pH. If it’s not right, your plants can’t absorb the nutrients you are giving them.

Photosynthesis, which enables your plants to create energy from light, is an important part of their growing process. The chlorophyll in the plant (the stuff that makes it green) is what captures sunlight and gives the plant energy. Magnesium is key to this process and is an important nutrient to consider.

Calcium helps make the plant strong. Sulfur helps the plant produce enzymes and proteins and aids the production of chlorophyll. It also improves the growth of roots and production of seeds.

If a plant is lacking in these basic macronutrients, then the leaves will turn yellow and the plant won’t be healthy.

In addition to the macronutrients, there are other micronutrients that are essential for the health and potency of your crop. Although these aren’t required in large amounts, they are still essential and include:

  • Molybdenum
  • Zinc
  • Copper
  • Silicon
  • Cobalt
  • Manganese
  • Boron
  • Chlorine

They all help the plant to metabolize, reproduce and thrive in different ways.

rich soil for growing plants

Hydroponic Nutrients and Growing Mediums

Growing cannabis hydroponically involves a water-based growth medium other than soil, such as coco noir, clay pebbles, water or rockwool. This way of growing marijuana plants is becoming increasingly popular and can produce a bigger yield than soil grown plants, increasing it by 25 to 30 percent.

Adding nutrients to these growing mediums can be easier as the plans only need enough of the medium to keep them upright. The roots are more open and easily absorb oxygen and nutrients, making it a more efficient growing system.


As a result of the increased yield, many of the nutritional products available for growing cannabis are hydroponic nutrients. They come in liquid or powder form. Whichever you choose, they must be diluted in the correct ratios, or you can overfeed your marijuana plants.

These nutrients might be labeled as either “grow” or “bloom.” Grow nutrients are high in nitrogen for growth in the vegetative stage. Bloom nutrients, on the other hand, are high in phosphorus to encourage flowering. Make sure you get the right one for the stage of development your plant is in.

Unlike soil, growing in a hydroponic medium can be unforgiving if you get the amount of nutrients wrong. You can actually end up killing your plants. For this reason, you are better off starting with about a quarter of the recommended dose and increasing it as needed.

Whichever hydroponic medium you use, remember to check the pH levels, especially if you are feeding your plants but they aren’t thriving. Ideally, you will want it to be about 6.0. You can buy many different pH testers, like this one from Oakton.

testing the ph of water

Which Should I Use, Soil or Hydroponics?

There are many ways you can grow cannabis plants. Some involve lots of expensive high tech equipment. Some are as basic as soil and a pot, or a grow-bag in your garden.

It’s worth remembering that cannabis has been grown successfully for millennia. There’s no need to feel pressured into following the latest fancy trend. You can stick to time tested basics.

Using organic soil can be a good idea if you are new to marijuana growing. It might not be as detrimental if, or when, you make mistakes, and will stand up to less than ideal conditions. The downside is the growth might be slower and the yield will probably be lower.

Soil differs from hydroponics in that it contains organic matter which is non-inert, like compost, humus, worm castings and manure. These supply many macronutrients and micronutrients to the soil. Things like fungi and other microbes process these non-soluble substances, so the plant can use the nutrients.

This means that non-organic nutrients can build up in soil, preventing the plant’s roots from absorbing water and nutrients.

Organic nutrients and fertilizers usually contain more elements which are better for the soil and the plants. If you’re a newbie, you might better off sticking to organic growing if you’ll be using soil as the growing medium.

There are commercially available soil blends which contain all the organic nutrients you need. On the other hand, you can get organic nutrients which are premixed and help take the guesswork out of plant feeding. Although they can be costly, you just follow the instructions given, and the results are generally good.

Hydroponics are less forgiving and need more attention, some expertise, and more of your time. The upside, as I have mentioned, is you can get quicker flowering times and a bigger yield from your plants—if you get it right.

Go with what you feel comfortable with, and what suits your budget and your time. You don’t want to end up spending money unnecessarily on paraphernalia you won’t use. Do your research before you get started, to make sure you are using products which are compatible with your growing medium.

How Much Difference Is There Between Nutrient Brands?

There’s no doubt about it, growing cannabis and trying to figure out which nutrients you need can be like walking through a minefield. This is especially the case if you're a new grower. Trust me, even with my knowledge of plants it’s some trial and error to get it right.

The companies selling nutrients produce many different types for a wide range of purposes.

The main thing to bear in mind is giving your green babies the right nutrients at the right time. This means using certain ones for vegetative growth and different ones for flowering.

Even though the ingredients in products can vary from brand to brand, many of the products are very good. The manufacturers use different formulas and techniques to create what they think is the best mix for optimal growth.

Although the ingredients vary, they can still add up to the same overall nutrient ratios. This means two different sets of ingredients can produce the same N-P-K ratio from different levels of nutrients.

It is worth repeating that the main thing to check is that you have the right nutrients for your growing medium, soil or hydroponics.

The other thing to make sure you don’t do is confuse supplements with nutrients. Supplements will generally have a very low N-P-K ratio.

Provided you are feeding your plants with the right N-P-K and suitable micronutrients, supplements should not be needed. Adding them to the mix could end up burning your plants and ruining your crop.

Frequently Asked Questions About Marijuana Nutrients

What Is the Best N-P-K Ratio for Flowering?

NPK for flowering

Photo by Esteban Lopez on Unsplash

We have already covered this briefly above. Once your plant hits the flowering stage then you need to reduce the nitrogen and up the phosphorus and potassium. A ratio of 1 percent nitrogen, 2 percent phosphorus and 3 percent potassium (N-P-K 1-2-3) is good for early flowering and easy to remember.

Once your flowers enter the mid-stage then you can increase the level of phosphorus to about 3 while keeping the nitrogen at 1. For later stage flowering, reduce the phosphorus back to 1 and increase the nitrogen back to 2.

How Often Do I Need to Feed My Cannabis Plants?

This all depends on your growing medium. These guidelines should be helpful:

  • Growing in soil outdoors: Growing your cannabis in a good soil outdoors where they get plenty of sun and water can mean they don’t need a lot of added nutrients. There will be times when you will have to water them and this is a good opportunity to add marijuana fertilizers.
  • Mediums without soil: If your weed is growing in conditions such as peat and sphagnum, it will require watering on a regular basis and need plenty of cannabis nutrients added. As a rule of thumb, when the top of the growing medium is dry to the touch, water your plants. Add your marijuana fertilizer to the water.
  • Using Coco Noir: If this is your growing medium, then again your plants will need lots of feeding. There should be plenty of run-off and nutrients should be supplied to the medium with water daily.
  • Hydroponics: With a true hydroponic medium, the roots of your plant are always in water. Hydroponics nutrition should be added constantly to the water when it’s topped up. This is the only way your plants can get the nutrients they need to grow.

What Are Big Bloom Nutrients?

Big Bloom is one of a range of nutrients supplied by Fox Farms. It’s an organic, environmentally friendly, plant food for cannabis and other plants.

It is formulated to encourage the growth of large, strong blooms. It also promotes sweeter tasting fruit and thicker seed pods. This fast-acting liquid nutrient has a lot of bat guano and worm castings in its mix.

It’s good for cannabis plants grown in soil or hydroponically. It features alongside two other Fox Farm products in a trio of the best nutrients for cannabis in my reviews below.

Can I Overfeed My Plants With Cannabis Nutrients?

The simple answer is yes, you can. If you think about it, plants are a bit like us, they thrive when fed little and often. Overeating or going hungry makes us feel unwell; the same applies to plants.

Signs that you have overdosed on your cannabis nutrients include:

  • Yellowing or wilting leaves.
  • Brown marks at the leaf edges and margins.
  • Brown or black rotted roots.
  • Little or no growth.
  • Dropping leaves.
  • A crust of fertilizer build-up on the soil.

Adding too much fertilizer to your soil or hydroponics prevents the plant from taking up water and results in leaf burn. This happens because the water pressure between the roots and the soil reverses. This means the water is drawn from the plant rather than being absorbed into it.

It’s best to add marijuana fertilizers little and often, and most importantly, consistently. Don’t just shock your plants with a lot of nutrients every now and again. For this reason, apply well-diluted nutrients, starting at about quarter of the recommended dose.

You can always increase the amount if necessary but you can’t take it away.

The Best Nutrients for Cannabis

small cannabis seedling

Picture courtesy of Pixabay

We already mentioned there is a plethora of nutrients available on the market. Trying to work out which ones you should choose can be overwhelming. Never fear, I have done the legwork for you to give you the best choices .

There’s no doubt that having the best cannabis nutrients is important, especially if you’re growing hydroponically. Let's take a closer look at what I think are the best nutrients for growing cannabis.



#1 Best Overall Nutrients for Growing Cannabis - Advanced Nutrients Bloom, Micro & Grow

This combo pak from Advanced Nutrients gives you what you need through all the stages of your marijuana plant’s growth.

The pack has one liter each of Grow, Bloom and Micronutrients, and can be used for either soil or hydroponic mediums. The N-P-K ratios are 1-0-4 for grow, 1-3-4 for bloom and 2-0-0 for the micronutrients.

What I really like about this product is it also helps balance the pH. You won’t have to worry about your plants not absorbing the nutrients this system supplies. The technology used ensures the pH is maintained as well.

Chelates are included in the ingredients for these cannabis nutrients, which helps absorption, and fulvic acid helps the plant grow.

Each of the product packaging is a different color so you don’t accidentally use the wrong one at the wrong time. The nutrients are easy to use, making them a good choice for new growers and experts alike.

The company is so confident in its product that it offers a 100 percent money-back guarantee for six months. They simply ask you to return the unused product with your receipt and they will refund your money.

Pros

  • Adjusts pH automatically.
  • Easy to use.
  • All-in-one package of marijuana nutrients.
  • Suitable for hydroponics or soil nutrition.
  • Added chelates and fulvic acid for nutrient absorption and growth.
  • Money back guarantee.

Cons

  • Directions need to be followed carefully.

#2 Best Marijuana Fertilizers for Soil - Fox Farm Liquid Nutrient Trio

Fox Farm brings us another 3-part combo of the best nutrients for cannabis in liquid form. Each bottle contains 32 ounces.

First is Grow Big Hydro, with an N-P-K of 6-4-4, aimed at boosting your plants through their vegetative stage.

Next comes Tiger Bloom with an N-P-K of 2-8-4, to be used once your first buds appear. This high phosphorus marijuana fertilizer will boost flowering potency and increase your yield.

Finally, the third bottle is Big Bloom, with an N-P-K of 0.01-0.3-0.7. It can be used through all the growing cycles to increase nutrient uptake and keep root systems healthy. It will also encourage large, strong flowers.

There is a different bottle for each stage of growth so you don’t get mixed up with which one you should be using when. Provided they are used in the correct order your plants should thrive. Just remember start at a quarter of the recommended dose to be safe.

Fox Farms also have a handy feeding schedule you can refer to on their website to help you along.

If hydroponics are your thing, the company does produce a similar trio geared for hydroponics nutrition.

Pros

  • Easy to use, even for inexperienced growers.
  • Good for early growth and late buds.
  • Feeding schedule available.
  • Can be used on other household plants and vegetables.

Cons

  • Need to monitor soil pH closely.

#3 Best Nutrients for Cannabis on a Budget - Dyna-Gro Liquid Grow & Liquid Bloom

This offering from Dyna-Gro has been described by some as the best fertilizer for weed which doesn’t break the bank. I definitely agree! It comes in two blends, a grow and a bloom. You get an 8-ounce bottle of each in the package.

While made for growing veggies, flowers and all sorts of plants, your cannabis will also benefit from it. All the macro and micronutrients your marijuana plants need are included in the ingredients. The grow blend has a 7-9-5 N-P-K ratio and the bloom has a ratio of 3-12-6.

These blends are suitable for soil or hydroponics; just follow the correct dilution for the medium you are using. Directions for use are supplied on the bottle, along with the ratios for dilution.

These concentrated nutrients are easy to mix and use and can help all your plants grow bigger and better.

Pros

  • Concentrated formula.
  • Helps through growing and blooming cycles.
  • Works for any growing medium.

Cons

  • The nitrogen level in the “grow” formula seems to be a little on the low side.

Are you growing your marijuana in a medium other than soil? this combo of nutrients from General Hydroponics could be just up your street. Each one-quart bottle has a blend of nutrients that will see your plants through a specific growth stage. Just dilute the requisite amount from each bottle as directed for vegetative growth and flowering.

The first one, FloraGro, has an N-P-K of 2-1-6 to help strengthen the roots of your plants and stimulate the growth of the vegetation.

Moving on to the second stage, you get FloraBloom, with an N-P-K of 5-0-1. It’s high in magnesium, potassium, sulfur and phosphorus to stimulate floral growth. It also claims to enhance the aroma and flavor of your cannabis.

Finally, we get FloraMicro, with a 0-5-4 ratio and supplying trace elements as well as calcium, potassium and nitrogen. This helps your plants stay strong and healthy through all stages of growth.

Interestingly, this series of nutrients is apparently used by NASA and scientists doing Antarctic research to enhance plant growth.

There are a number of feed charts you can refer to on the company website, or you can use their template to custom your own. There is also a very good FAQ section, covering the Flora system of nutrients.

Pros

  • Can be used for soil as well as hydroponic mediums.
  • Supplied feeding schedules on website or customize your own.
  • Concentrated formulas.

Cons

  • Can be difficult to measure small amounts.

#5 Best Organic Nutrients for Cannabis - General Hydroponics Organics Go Box

General Hydroponics supplies this box with two full size 16-ounce bottles of Bio Thrive Grow and Bio Thrive Bloom. The box also includes six different 8-ounce bottles, each containing various plant supplements. Two of these are Bio Weed and Bio Bud, designed for application during the vegetative and flowering stages of your cannabis plant respectively.

None of the products in the box contain any chemicals; they are all organic which is a great choice for a growing number of people nowadays. There is an instruction manual supplied, along with a schedule for feeding your weed. A nutrient feeding chart can also be found on the company website.

There are no N-P-K ratios listed for these nutrients, however they seem to work well for many users. Suitable for both soil and hydroponics, you have all the nutrients you need in one package, and some additional supplements as well.

Pros

  • Easy to use with instructions included.
  • Works for all types of plants.
  • Can be used in soil or other growing mediums.
  • All organic.

Cons

  • No N-P-K ratios.
  • Smell can be pungent and unpleasant.

#6 Best Plant Food for Cannabis - Humboldts Secret Plant Food

Humboldt Golden Tree is not strictly a nutrient but a booster that works alongside your existing feeding regime. It claims to reduce the vegetation time of your plants by 50 percent and increase yield by 20 percent. Many find that it does just that.

This professional-level marijuana fertilizer can be used in all growing mediums to boost the plant’s photosynthesis. It works by activating the enzymes involved in growth and energy supply, and has an N-P-K of 0-0-2.25.

It comes in a range of sizes, from 2 ounces right up to 5 gallons. Whether you have a single plant or a whole garden full, there’s a quantity to suit your needs.

Humboldt does produce its own 2-part nutrient kit but states that Golden Tree can be used with any other nutrient brand. This applies whether you are using soil or hydroponics for your cannabis babies.

Pros

  • Decreases growth time.
  • Boosts and enhances blooms.
  • Increases yield.
  • Easy to use in soil or hydroponics.

Cons

  • Has an unpleasant smell.
  • Other nutrient systems are still needed.

#7 Best Nutrients for Cannabis for Beginners - Advanced Nutrients Hobbyist Grower Bundle

If you are just dipping your toes into growing your own weed, then you might not want the complication of dealing with advanced nutrients. This basic four-step nutrient kit from Advanced Nutrients works alongside your existing nutrient regime. It won’t give you a headache trying to work out what extra nutrients to add or when to add them.

Voodoo juice, the first product, is a root treatment that will enhance the growth of your plants. Follow that by B-52 (and I don’t mean the alcoholic cocktail). This all-around supplement will enhance any base nutrients.

The third product, Big Bud, does what it says on the package: it enhances the size of your buds. Finally, Overdrive will keep your flowers and fruit production going longer.

What’s great is this set also helps balance your pH so you won’t have to measure it all the time.

Each bottle is 250 ml; however, while they are small, they are also highly concentrated.

Pros

  • Easy to use for beginners.
  • Can be used in soil or hydroponics.
  • Balances pH.

Cons

  • Still need to use basic grow/bloom nutrients.

Conclusion

Finding the best nutrients for growing cannabis, especially when you are an inexperienced grower, can be a challenging task. The good news is, it doesn’t have to be that way. Until you are more confident in your growing abilities, there is no need to over-complicate matters.

Any of the cannabis nutrients I have reviewed will help you feed your plants and give you a healthy and abundant crop. They will all offer your marijuana plants maximum support to keep them strong. Just make sure you choose the best one for the medium you are growing in, and follow the directions.

If I had to pick a favorite it would be Advanced Nutrients Bloom, Micro & Grow. It’s easy for beginners and also the more knowledgeable among us to use.

As well as a good balance of cannabis nutrients for each stage of growth, it also helps balance pH. This applies whether you are growing in soil or a hydroponic setup. Furthermore, I like the company’s confidence in offering a money-back guarantee.

The ultimate choice is yours, but hopefully you now have more knowledge to confidently choose the best nutrients for cannabis plants. No matter which of these nutrients you choose, both you and your plants will be happy.