Choosing a good substrate for indoor plants is the first step to achieve a successful grow. As a matter of fact, it’s a fundamental decision that will determine the future of your crop, as the substrate is the base of the plants, where they grow their roots and where they get their nutrients from.

There are various characteristics that differentiate a poor substrate from an excellent one, but the most important features are airflow and water retention. In order for plants to grow properly, they need a good base to develop their roots freely (a lumpy substrate makes this difficult), to hydrate themselves and to obtain the necessary nutrients (the water retention capacity of the substrate facilitates this step hugely).

The perfect substrate is the one that has the perfect pH and EC levels for the grown plants in particular, a correct NPK distribution and it’s easy to mix with fertilizers and additives. A good substrate can be made of plenty of materials, and some growers even prepare their own great quality substrate using natural products. The perfect substrate for indoor plants is made of organic and mineral materials.

best substrate for indoor plants

What materials should a good indoor substrate have?

Each cannabis plant has its own needs, therefore, the market features a great variety to meet them all. However, indoor plants have very concrete requirements.

Cannabis plants should grow with an organic base, such as peat (which has plenty of nutrients on its own), mixed with mineral materials to boost the most important characteristics, like for example coco coir or perlite.

  • Coco coir is an inert material that, when mixed with peat, improves substrate’s airflow and provides it with a spongy texture, which encourages root development. It also helps counteract cultivation mistakes.
  • Perlite is a type of volcanic rock that improves airflow and increases water retention, making it easier for plants to absorb all the necessary nutrients.
  • Rockwool is an inert material that promotes great plant development, but it has some drawbacks, such as its high lime content in its pH. If you decide to use it, you should lower acidity with specific products.
  • Arlite or expanded clay is very popular in hydroponic grows, although it can also be mixed with an organic material to use as an indoor substrate. However, its nutrient absorption capacity is rather low, thus, you need to keep a good eye and use fertilizers at the right moment.

The best substrates for indoor plants

Now that we have explained what composition a good indoor substrate has, it’s time to choose the best ones among the GB The Green Brand catalog.

All Mix, by Boom Nutrients

All Mix, by Boom Nutrients, is a fantastic substrate that provides all the necessary nutrients to grow a great quality and strong grow. It’s suitable for growth and for flowering and contains organic nutrients, like worm humus and bat guano, which help plants obtain all the micro and macro nutrients they require, as well as the right amount of NPK.

Using additives and fertilizers like Micro Boom, Delta Boom or Resin Boom along this substrate guarantees a generous and potent yield.


  • Black and blonde peat
  • Worm humus
  • Bat guano
  • Perlite
  • Magnesium, sulfur, humic and fulvic acids
  • Extra PK for plants
all mix by boom nutrients

Complete Mix , by Top Crop

Complete Mix, by Top Crop, is an excellent option for growing plants. This light substrate includes coco coir and small amounts of worm humus. It’s perfect for indoor crops, although spraying it with fertilizers is highly recommended as it doesn’t contain large amounts of nutrients.


  • Coco coir
  • Vegetable compost
  • Blonde peat
  • Perlite
  • Leonardite
  • Macro and micro nutrients
  • Organic matter over dry matter 76.2%
complete mix by top crop

Terra Professional Plus, by Canna

Terra Professional Plus, by Canna, is a great alternative for indoor grows, especially during the rooting or growth phases. This substrate is made of peat and coco coir, therefore, it has a tendency to get dry fast. To prevent excessive dryness, the recommendation is to mix it with perlite or similar. Doing so will increase airflow and water retention.


  • Sphagnum peat
  • Coco coir
  • Compost pine bark
  • Organic and inorganic manure
  • NPK: 12-14-24
  • Organic matter over dry matter 85%
terra professional plus by canna
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Erik Collado

With more than 10 years of background in the cannabis sector, his experience and knowledge are the base of GB The Green Brand’s success

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