Best Nutrients and Fertilizers for Growing Cannabis Reviews

Laws around the world are starting to change when it comes to marijuana.

Cannabis seedling coming out of the seed

Growing is becoming an increasingly popular choice.

With a simple set-up like a grow tent and some LED lights, you can make sure you have enough marijuana on hand at all times without spending a fortune.

If you’re stuck for choice with seeds, check out this series of articles. We spent plenty of time testing a wide range of strains and there’s something for everyone.

Once you have everything up and running, you need to give your plants a helping hand…

How about getting the best nutrients and fertilizers for growing cannabis?

We’ll look first at getting things right when it comes to fertilizing your crop.

After that, we’ll look at 5 nutrients and fertilizer reviews so you can easily check out the best products on the market.

Do You Need To Use Nutrients and Fertilizers for Growing Marijuana?

Marijuana plant growing out of fertile land

In a word, yes.


Proceed with caution.

Marijuana plants turn light into energy through photosynthesis. This means there’s no need whatsoever to apply chemical fertilizers with a heavy hand.

There are plenty of variables. Mainly, though, you’ll want to think about 2 broad areas:

  • Nutrients suitable for your chosen strain of weed
  • Fertilizers appropriate for the growing medium

Base Nutrients for Marijuana

When you’re looking at nutrients, there are 3 main ones prominently displayed:

N - nitrogen, P - phosphorus, K - potassium (kalium)
  • Nitrogen (N)
  • Phosphorus (P)
  • Potassium (K)

These appear in the same order. The numbers refer to percentages of the above nutrients.

A 15-10-15 mix would contain 15% nitrogen, 10% phosphorus and 15% potassium. The remaining 60% is inert filler and secondary elements.

You want to get the NPK levels right for the best crop.

As an overall guideline, think about the main stages:

  • Rooting and Germination: Go for more phosphorus with less nitrogen and potassium
  • Vegetative Stage: You need plenty of nitrogen
  • Flowering: More phosphorus and potassium along with some extra calcium for good measure

Important Note: Whatever feed you are using, stop 2 weeks before harvest. This allows time for the chemicals to be flushed fully from your plants.

Why Use Nutrients or Fertilizer For Cannabis?


Nitrogen is used in every growth process and is indispensable. This is the principal component of amino acids.

The energy obtained from nitrogen is transferred and stored in large part due to phosphorus.

Flowering and the uptake of water is helped by the potassium.

In addition to the trusty NPK trio, there are many other nutrients that also play their part.

Calcium is necessary for your plants to build up strong cell walls and healthy roots.

For the vitamins and proteins necessary for producing chlorophyll, sulfur comes into its own.

Magnesium is another key component for chlorophyll.

Other nutrients like boron and copper, iron and zinc are beneficial in trace quantities.

Nutrients will make the difference between your plants just getting by and truly flourishing.

What Is Special About Nutrients For Marijuana?

It is possible to use standard houseplant feed but there’s always a risk.

Since you have doubtless invested a great deal of time and money in your crop, you are far better off going for something specifically designed for cannabis.

Getting your feeding regime right is far more about how and when your plants need a helping hand than what you use.

Think about what works best in the germination, vegetative and flowering stages. Do plenty of reading and research.

Get the logistics right and you could be enjoying a bumper harvest. Get things wrong and you could do more harm than good.

Can You Grow Without Nutrients?

It is possible to grow weed completely organically. This is only practical, though, if you are growing in soil. For hydroponic set-ups, this is not an option.

Even with soil, you’ll be reliant to a large extent on luck to pull things off without adding nutrients. To succeed, you’ll need highly fertile soil and a strain designed to grow freely and easily. The alternative is to purchase specialized soil.

What Happens If You Use Too Much Feed?

Seeds of Cannabis over white background

Feeding in a heavy-handed manner can create all sorts of problems for your plants. It’s far more damaging than not introducing enough nutrients.

If you see erratic leaf sizes or sagging branches, you could be in trouble. Other potential flashpoints include yellowing leaves or chemical burn.

Awkwardly, these symptoms are very similar to plants suffering from a lack of nutrients. This makes diagnosis pretty tough.

One way to test things is to ease back to a simple, balanced soil along with water for a few days…

If the plants start to perk up, it’s likely you were overfeeding them. If the problem continues or gets worse, ramp up the feeding pronto!

5 Best Nutrients and Fertilizers for Growing Cannabis Reviews

Product Name





Our Rating

Fox Farm FX14049 Liquid Nutrient

Fox Farm FX14049 Liquid Nutrient

Grow Big: 6-4-4
Tiger Blom :2-8-4
Big Bloom :0.1-0.3-0.7



Editor Choice

General Hydroponics 3 Pack

General Hydroponics 3 Pack

Grow Big: 3-1-7
Micro: 5-0-1
Bloom: 0-5-4




Advanced Nutrients Bloom, Micro & Grow 3 Pack

Advanced Nutrients Bloom, Micro & Grow 3 Pack

Grow: 1 – 0 - 4
Micro: 1-3-4
Bloom: 2-0-0




Advanced Nutrients Bud Candy Fertilizer

Advanced Nutrients Bud Candy Fertilizer


Single bottle



Humboldts Secret Golden Tree

Humboldts Secret Golden Tree


Single bottle



When it comes to nutrients for marijuana, Fox Farm is a hard-hitter in this space. As well as producing their own line of soils, they also specialize in plant feed.

With this handy pack, you’ll get just what you need for the 3 different stages…

  • Grow Big
  • Tiger Bloom
  • Big Bloom

Grow Big Hydro comes in at 6-4-4 on the NPK scale. You can get things rolling with this and stimulate energetic growth during the veg cycle. For a standard feed with Grow Big, use 12mls per gallon. Jack this up to 20mls per gallon if you are looking for a heavy feed.

As well as the main nutrients, Grow Big also contains Norwegian kelp and earthworm castings. There is a chelating agent thrown in so your plants can better absorb these valuable nutrients.

Break out the Tiger Bloom when you spot your plants start to flower. It’s a phosphorus-based 2-8-4 NPK. Also blended in are calcium and magnesium, potassium and kelp along with some earthworm castings. All of this combines to enhance flower development. Ensure your plants get their NPK along with all the micronutrients they need.

Big Bloom is great to use throughout the entire grow. This is 0.1-0.3-0.7 NPK. Fox Farm advises that you shoot for 20mls a gallon on a weekly basis. Continue throughout the entire cycle.

By including this liquid feed in your regime, you can enjoy sweet flower brimming with health. It can also help to increase the size of the flowers. The inclusion of bat guano enhances taste, potency and yield. Using Big Bloom is a fantastic way to deliver the organic fertilizer and nutrients your crop will appreciate.

While this pack might not seem particularly cheap, when set off against the other elements of your grow, it’s almost pocket change. Use this potent trio in combination and you will reap the benefits at harvest time

Next up is another 3 pack of nutes from General Hydroponics, another legend in the industry.

There is a dazzling array of choices when it comes to size. We went for the quart option.

General Hydroponics have heavily promoted their Flora Fertilizer Set so you might well have seen one of their many ads. They point out that NASA scientists have relied upon their fertilizers to successfully raise plants in hostile conditions. This is encouraging if you want to use them in a controlled growing environment at home.

The Flora Series is now as the original Building Block system of nutrients. If you want to boost yield and also maximize crop quality, this feed will powerfully deliver all the primary, secondary and micronutrients your plants are crying out for.

This batch of feed allows you total flexibility. You can tweak the mixtures according to the specific needs of your plants. The concentrates are purified so that they are perfectly soluble.

There are 3 of these extremely concentrated liquid nutrients:

  • FloraGro
  • FloraMicro
  • FloraBloom

FloraGro helps your plants to set down strong roots during the vegetative stage. NPK is 3-1-7. Throw in some FloraGro for rich vegetative growth.

FloraMicro is superb during the growth and bloom cycles of your plant. NPK levels are 5-0-1. This is a wonderful base nutrient mix.

FloraBloom comes in at an NPK reading of 0-5-4. This is added when your plants are flowering for the crop you deserve.

If you are on the trail of a mineral-based nutrient that will pay dividends at harvest time, pop this pH-balanced 3 pack on your shortlist. It will not disappoint.

Advanced Nutrients offer products tailor-made for experienced growers. If you know what you want from your nutrients and want to mix them up according to taste, you can’t go far wrong with these products.

Bursting onto the scene back in 1996, Advanced Nutrients have been producing a full range of products for the marijuana connoisseur ever since.

This is another 3-pack in 1-liter bottles. You also have the option of 4 liter or 10 liter sizes.

The team of scientists at Advanced Nutrients ensure that the carrier-molecules they use get the very most out of the feed and deliver it efficiently and effectively to your plants.

You’ll get the same 3 variants as with the General Hydroponics set:

  • Grow
  • Micro
  • Bloom

With the Grow (1-0-4 NPK), you can get things warmed up nicely. Getting things right at the veg stage will make everything fall into place later down the line.

Micro is 1-3-4. It helps with the soil and roots. Also, as the name suggests, it included all the micronutrients demanded by your crop.

For flowering, the Bloom (2-0-0) steps in to level you up to a crop you’ll be proud of.

To use these nutrients as intended, use them in equal parts. You can experiment but only do this if you really know your stuff.

For pH-perfect nutes that won’t cost you a fortune, you’re in safe hands with this nifty 3-pack from Advanced Nutrients.

With NPK levels of 0-0-1, the Bud Candy fertilizer has only phosphorus and no nitrogen or potassium.

If you are bringing on clones or seedlings, Bud Candy will strengthen their chance of coming through.

Heavy in magnesium, you can prop up the growth of your plants right on through the sixth flowering week.

Advanced Nutrients products are designed to work very well in combination. Bud Candy slots in neatly with the Big Bud liquid feed we will look at to round out our reviews.

With this fertilizer, you can really max out the genetics with a real boost in taste and smell.

As with all fertilizers, it pays to flush fully a fortnight before harvest. This will get rid of any lingering chemicals and allow your plants to ripen fully.

For a higher yield with a sweet flavor, invest in some Bud Candy today. It will not disappoint.

While our other tested products are all specifically designed for marijuana, Humboldts Secret is an all-rounder that works wonders with a wide assortment of flowers, fruits and vegetables. It also happens to give marijuana the leg-up it needs.

There is a choice of sizes. We opted for the 16-ounce bottle. This will make up to 250 gallons of feeding solution.

Using this consistently well-reviewed fertilizer does not just add 20% on to your yield but can also halve the time your plants spend in the vegetative stage. If you are not using auto-flowering seeds, this is a nice touch. With such a valuable cash crop, this is a real win-win situation.

When your plants are in the vegetative cycle, add 2ml of the feed per gallon into your reservoir. Pop in the base nutrients until your PPM levels in the mixture hit 1000 on the Hanna Scale.

While flowering, you need 5ml for each gallon.

If you need to step in and rescue your plants, step things up to 15-30ml per gallon.

Cut doses in half if you are growing with hydroponics.

For a classic fertilizer that will really make your crop golden, why not find out Humboldts Secret? Whatever that secret is, the results speak for themselves.


We trust you’ve enjoyed this look at how to fertilize your crop effectively.

Give us a shout with any questions or feedback at any time. We love to hear from our readers.

Come back soon for more advice on getting the very best out of your marijuana crop.

Happy growing!

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