Soil or Hydro

Soil or Hydro
hydro and soil system for marijuana

Most people who start growing choose soil. It’s a lot cheaper than hydroponics and you can cultivate a fully organic product.

The yield is a bit lower, but there is more room for error, because the soil forms a buffer for nutrients.

A frequently asked question is about what’s better; growing in soil or in hydroponics.

However, these are two very different methods, each with their own advantages and disadvantages.

Growing on hydro is much more technical and a lot more expensive. There is also less room for error.

But the yield can be quite a bit higher than with soil. And since it’s a ‘cleaner’ method, there is a lower chance of bugs and diseases.

Another advantage is that you don’t have to carry bags of soil around all the time.

I always advise beginners to start with soil to gain some knowledge and to see if they like their new hobby.

If you notice that you’re starting to get the hang of it after a couple of harvests, you could move on to hydro.

I still grow most of my products in soil, and I also used for the grow journal in this course.

growing marijuana in soil
Growing marijuana in soil


The environment the roots grow in is very important. There needs to be enough oxygen, a gentle temperature and always sufficient water, so the plants can absorb water whenever they need it.

You also have to add all the minerals the plants need in order to grow properly.

Growing indoors in soil is not the same as growing outdoors in soil. Outdoor plants have a very large root system that can extend very far in search of water and nutrients.

Indoors, plants are in pots and the root system can’t grow as much as outdoors.

That’s why we have to make sure the plant always has enough water and nutrients available.

The plants feed themselves by taking nutrients from the soil. But the roots can only absorb the small elements if they’re dissolved in water.

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So all animal droppings, dead plant material and decomposing animals that are present in nature have to be broken down to much smaller particles.

This is done by bacteria that live in the soil. When it rains, these small particles dissolve and the roots can absorb them.

Indoors, it’s quite difficult to create the same environment as outdoors.

It’s also not a good idea to take soil from outside in, because there’s a big chance of bringing in parasites and harmful insects this way.

It’s best to buy a good soil mixture at a garden center, or even better, at a growshop. Brands such as Fox Farm are specially developed for marijuana cultivation.

They’re a bit pricier than soil from the garden center, but they contain all fertilizers and the right bacteria.

hydro marijuana growing system
Hydro system


In order to prevent certain problems that can occur when growing in soil, such as a larger chance of diseases and a lower yield, you could choose to grow on hydro.

The plants will then grow in an inert growing medium without soil, usually of mineral origin. Think for instance of products like rockwool, perlite or clay pellets.

If you’re growing in soil, a part of the nutrients is contained in it.

Rockwool for instance has no nutrients naturally present, so you need to mix these with the water you give your plants.

The substrate (rockwool, clay pelelts) only serves to keep the plant upright and to transport the nutrient solution through oxygen bonds.

And the more oxygen present in the substrate, the more nutrients the plant can absorb. Check out this very cool hydro system; bubble buckets

Download my free marijuana grow guide and start growing healthy marijuana plants.


In a hydroculture, the substrate replaces the soil. It’s inert and serves to ground the roots and for the oxygen transfer of the nutrient solution.

There are different substrates you could use. The most common ones are rockwool, clay pellets, perlite and cocopeat.

Depending on the structure of the substrates and the capacity to contain water and minerals, they have to be irrigated in different ways.

The substrates that can contain water are irrigated in cycles and the substrates that can’t are continuously irrigated.

Hydro 2 rockwool

Rockwool is used mostly by professional growers because it’s cheap, light and properly retains water and air. Moreover it’s a mineral, it’s sterile and inert.

It looks a bit like glass wool insulation, but make sure you buy rockwool that’s suitable for cultivation, because this has a neutral pH and doesn’t contain any harmful substances.

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Rockwool has to be irrigated several times a day. If you irrigate it too much, the roots can become moldy because of a lack of oxygen.

If you don’t irrigate it enough, the growth slows down, possibly causing damage to the plant. It’s difficult to find the right cycle in the beginning.

In any case you could attach a pump to a time switch and have it inject a certain amount of water into the rockwool every six hours.

Plant features

Soil and Hydro
Clay pellets

Clay pellets are the most ecological substrate and it’s super easy to grow on clay pellets. By heating little grains of clay they expand and become hard balls.

Since the clay pellets can’t absorb water, they can be permanently irrigated. It’s sometimes used in passive systems, but clay pellets are particularly interesting for active systems.

Due to the structure, the nutrient solution gets an optimal oxygen input and it’s impossible to give too much water.

Clay pellets are fun for hobby growers who like to try out hydro and don’t want to take the risk of their roots drowning.

In addition, the clay pellets can be used for the next harvest, which makes it very cheap. The yield is higher than when growing on soil, but the installation is a bit more expensive.

Substrates cocopeat

Cocopeat is a substrate based on the husk of coconuts. Ripe coconuts fall from the trees, usually on sandy soil and the germinated seed develops inside that husk.

The cocopeat therefore serves as a natural substrate for the coconuts themselves. The cocopeat contains remarkable antifungal and antibacterial properties.

Cocopeat is an excellent ecological alternative to rockwool. Cocopeat retains water well, so it has to be irrigated in cycles.

It has the same characteristics as rockwool without the disadvantages, since the cocopeat ensures the retention of water and air.

It can be used for multiple harvests and doesn’t require special treatment.