Marijuana Fertilizer

Marijuana is a fast growing, hungry plant.

It needs to be fed well to give us a big, fat harvest.

If we don’t ‘feed’ our plants well, they’ll be hungry.

And you don’t want hungry plants because they will remain small, meek and skinny.


We need to feed it with good Marijuana Fertilizer.

2 part Marijuana Fertlizer

2 part Marijuana Fertilizer


Which fertilizer works well for Cannabis?

Most fertilizer will do. Even tomato plant food will work.

But there are fertilizers that are made especially for Cannabis.

Flora Nova‘ for example is made for Cannabis.

It works very well with soil.

It has all the minerals and nutrients needed into 2 bottles.

That means you’ll only need 2 bottles to get your plant all the nutrients they need. From small baby plant all the way to mature, budding fat stink-monster.

Flora Nova is available here.

All you need to do is mix the fertilizer correctly with water. I’ll explain how to get it exactly right here.

How is fertilizer given?

Most Cannabis fertilizer comes as a concentrated liquid in bottles.

That liquid is then mixed with water.

For example 1 table-spoon fertilizer mixed into 1 gallon of water

You then use that mixture to water your plants.


How often do I give fertilizer?

You give fertilizer all the time, starting when the plants are 2 weeks old.

That means; Every time you water your plants, there will be fertilizer in the water.


After giving fertilizer 3 times, you DON’T give fertiliser the next time. They need a break

For example:

If your plants are very young (3 weeks old), you likely give them water every 2nd day.

You water them Monday, Wednesday and Friday with fertilizer water. THEN on Sunday, you give them pure water (just water, no fertilizer). Then on Tuesday it’s back on fertilizer water.

That way some of the build up salt from the fertiliser is flushed out and your plants feel better.

Another example:

If your plants are mid-age (40 days old), you probably water them every day.

You give fertilizer Monday, Tuesday, Wednesday. BUT then on Thursday, they’ll get only clean water. And on Friday its fertilizer again for 3 days.

3 times fertilizer, 1 x pure water without fertilizer

How much fertilizer do I give?

Every fertilizer is different. They all have their own instructions written on the bottle.

But if you use Flora Nova, here’s how much you should give:

But first … you need a tool to get this right.

We want to do this right, so we can’t just guess. Right?

Let’s do some science!

Go on eBay and buy yourself a PPM meter. It’s not expensive.

A PPM meter measures how many minerals (nutrients) are in the water.

We need this so we can know how much to mix into our water.

PPM meter for dosing Marijuana fertilizer

A PPM meter tells you exactly how much fertiliser you should mix into your water

It’s an invaluable tool.

Buy a PPM Meter here.

Once you have that PPM meter:

Flora Nova comes as a set with 2 bottles: Growth and Bloom.

First, we’ll use Growth.

Mix the fertiliser as indicated in this schedule:

mariuana fertilizer feeding schedule


Always check the PPM value of your water.

Aim for the number given in the table above.

For example small plants can’t go higher than 300 PPM.

Mid-bloom plants get the most at 700-900 PPM.

Please note: If you are using Tap water and live in a ‘hard water’ area, it may already have a PPM of 300+ when it comes from the pipe.

You can’ add much fertiliser there. You may want to consider using a reverse osmosis water filter.

Water Quality: natural or filtered water is best

Using good water matters a lot.

Tap water is, unfortunately, not very good.

It has chemicals mixed not it. Chlorine and fluorine.

Noticed that swimming pool smell? Yeah, that’s chlorine.

Chlorine will kill beneficial bacteria in the soil.

Also, water from the tap often already has a high PPM. It’s difficult then to add fertilizer.

If you can, use water from outside. Like a pond, a spring or rain water.

Or install a reverse osmosis water filter. They cost around $150 and really purify your tap water.

water filter

Then you can add your fertilizer to that pure water. The plants will thank you.

Oh, and we humans may also benefit from drinking filtered water without chlorine or fluoride. but that’s another story.

Buy a Reverse Osmosis water filter for best results.

Too much fertilizer is harmful

I once went to somebody’s house to have a look at his plants.

He showed me a sad, small, wilting plant.

I asked him: ‘What happened?’.

He said: ‘I gave that plant lots and lots of fertlizer! To make it grow faster!’.

That plant never grew again and slowly died.

Poor plant!

The moral of the story is of course, that you cannot just give more fertlizer to make your plants grow faster.

They can only consume a certain amount.

And if you give too much, those fertilizer salts will remain in the soil and eventually harm or kill the plant.

So stick to the right amount and you’ll be golden.


Marijuana Fertilizer

Many Fertilizers use a 2 part solution. That means the user buys 2 containers and mixes them in water together before use.

This is necessary because certain elements in the fertilizer cannot stand each other and would cancel each other out if mixed directly. Most importantly, the calcium is kept separate from the sulfate i.e. in a 2-part, calcium is normally in part ‘A’, whereas sulfate is in part ‘B’.

Grow and Bloom needs diferrent fertilizers

Growth Phase

In the growth phase, plants have a particularly high demand for nitrogen. Consequently, “Grow” nutrients contain a relatively high concentration of nitrogen. Their use helps ensure plants do not run out of nitrogen prematurely.

Bloom Phase

In the bloom phase, the demand for phosphorus and potassium increases. Consequently, “Bloom” nutrients contain a relatively high concentration of both phosphorus and potassium, but relatively low nitrogen. Hence, switching to ‘Bloom’ during the flowering phase will help ensure plants do not become deficient in potassium and phosphorus (especially for heavy fruiting plants such as tomatoes and strawberries).

The use of ‘Grow’ and ‘Bloom’ nutrients at the appropriate times is also much more economical because for example, the use of ‘Bloom’ during the growth phase would result in excessive phosphorus and potassium being wasted. This wasted nutrient potentially becomes an environmental concern when the nutrient is dumped – particularly in large commercial operations.



  • Alexander Brautigam

    so how often did you use each of these fertilizers for your plants? i’m trying to figure out how frequently i would need to use this without risking damage to the root structures.

    • Jack Tambo

      There is no hard rule.

      Generally, I give fertilizer 2 times per week.

      Small baby plants don’t get any until the light is switched to 12/12 for flowering. Because the potting mix has enough in it until then.

      Then I start with a small dose. Whatever is written on the bottle as the smallest dose.

      The I increase weekly by 10%. Until the highest does as written on the bottle.

      Meanwhile you need to keep looking at the plant.

      Are too many leaves turning yellow? Give a bit more.
      Are the leaves rolling up or are brown spots appearing? Stop giving any for a week.