Marijuana Fertilizer 2017-08-10T07:44:11+00:00

Cannabis 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.

How to give Marijuana Fertilizer:


FloraNova Fertilizer on eBay

TDS Meter

Water filter

Cannabis feeding schedule (printable .pdf)

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.

2 part Marijuana Fertlizer

2 part Marijuana Fertilizer

It works very well with soil.

It comes in 2 bottles. For growth and bloom. This stuff works very well.

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 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.

BUT… remember the 3-and-1 rule!

After giving fertilizer 3 times, you DON’T give fertilizer 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 TDS meter. It’s not expensive.

A TDS meter measures how many minerals (nutrients) are in the water (Total Dissolved Solids).

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

PPM meter for dosing Marijuana fertilizer

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

It’s an invaluable tool.

Buy a TDS Meter here.

Once you have that TDS 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:

Feeding Schedule for Cannabis

(click to enlarge)

Click here to print this schedule (.pdf)

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.

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.

Why is there growth or bloom fertilizer?

Marijuana Fertilizer


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.

Links to buy the stuff:

  • Forrest Alan Marvin

    Is distilled water ok to use?

  • Krish

    Hey Jack,
    Any thoughts on using led strips SMD 5050 of RED and BLUE, each strip of 5m lenght of 60W, so adding up multiple strips to get about 240W.
    Will this work for growing?

  • Bruce Dill

    4 weeks into flower,and a few top leaves are yellowing with rust spots any sugestions

    • You may be giving too much fertilizer.
      Could that be possible?

      If you like, please post a photo and I can have a better look.

  • harmoniclive chromatic

    blood and bone works for me. some people dont like the idea but because it doesnt contain chemicals you dont risk burning the plant

  • 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.