The right substrate: the basis for lush harvests

If you want to be successful in indoor growing, you need the right foundation: the substrate. It is more than just a “holder” for the plants. It influences the nutrient supply, water availability and ultimately the health and yield of your plants. But the choice of substrates is huge! Soil, coco, rock wool… which one is right for you? In this article, we take a deep dive into the world of substrates, compare different options and help you find the ideal base for your green protégés.

What makes a good substrate?

An ideal substrate fulfills various tasks:

• Stability: It provides the plants with support and enables strong root growth.
• Water and nutrient storage: It stores water and nutrients so that the plants are supplied as required.
• Aeration: It ensures good aeration of the roots to prevent oxygen deficiency.
• Drainage: It drains excess water to prevent waterlogging and root rot.
• pH value: It has a suitable pH value to optimize the nutrient uptake of the plants.

Organic substrates: pure nature

Organic substrates consist of natural materials that decompose over time. They provide a natural source of nutrients and promote healthy soil life.

1. earth:

• Composition: Soil is a complex ecosystem of mineral and organic components. It contains important nutrients and microorganisms that promote plant growth.
• Advantages: Natural nutrient supply, high water storage capacity, forgives beginner’s mistakes.
• Disadvantages: May contain pests and diseases, compactable, heavy.
• Suitability: The classic in indoor growing, suitable for many different plant species.

Tip: Choose a high-quality soil that is specially formulated for indoor cultivation. Make sure it has a loose structure, a balanced nutrient content and a suitable pH value.

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2. coconut fibers:

• Composition: Coconut fibers are a renewable raw material with excellent properties for indoor cultivation. They offer good ventilation and water storage capacity.
• Advantages: High air permeability, good water storage capacity, sustainable, quick-drying.
• Disadvantages: Contains hardly any nutrients, must be fertilized.
• Suitability: Ideal for plants with high water requirements and rapid growth. Often used in combination with perlite or vermiculite.

Tip: Coconut fibers should be thoroughly soaked and rinsed before use to remove excess salts.

3. compost:

• Composition: Compost is a valuable organic fertilizer produced by the decomposition of organic waste. It contains many nutrients and promotes healthy soil life.
• Advantages: Rich in nutrients, improves soil structure, promotes beneficial microorganisms.
• Disadvantages: May contain weed seeds, not always consistent quality.
• Suitability: Can be used as an additive to soil or coconut fibers to improve the nutrient supply.

Tip: Only use mature compost that no longer contains weed seeds.

Inorganic substrates: For professionals and specialists

Inorganic substrates consist of mineral materials that do not decompose. They provide good drainage and aeration, but do not contain any nutrients.

1. perlite:

• Composition: Perlite is a volcanic glass that is foamed by heating. It improves the drainage and aeration of the substrate.
• Advantages: Very light, improves drainage and ventilation, stores water.
• Disadvantages: Contains no nutrients, can develop dust.
• Suitability: Often used as an additive to soil or coconut fibers to improve the structure.

Tip: Wear a respirator when handling perlite to avoid inhaling the dust.

2. vermiculite:

• Composition: Vermiculite is a mineral that is foamed by heating. It improves the water storage capacity and aeration of the substrate.
• Advantages: High water storage capacity, good aeration, stores nutrients.
• Disadvantages: Contains no nutrients, can become compacted if overwatered.
• Suitability: Often used as an additive to other substrates to increase the water storage capacity.

3. expanded clay:

• Composition: Expanded clay is made from clay that is foamed at high temperatures. It is particularly suitable for hydroponic systems.
• Advantages: Improves drainage, reusable, inert.
• Disadvantages: Contains no nutrients, can disintegrate with frequent watering.
• Suitability: Ideal for hydroponics and as a drainage layer in pots.

4. rock wool:

• Composition: Rock wool is made from molten rock. It is a popular substrate in hydroponics, but is also used in indoor growing.
• Advantages: Good ventilation, sterile, high capillary effect.
• Disadvantages: Contains no nutrients, non-degradable, may cause skin irritation.
• Suitability: Mainly used in hydroponics, but also suitable for growing in pots.

Tip: Rock wool can cause skin irritation. Wear gloves and a respirator when handling.

Choosing the right substrate: what is important?

Choosing the right substrate is an important decision in indoor growing. Consider the following factors:

• Plant species: Different plants have different substrate requirements. Find out about the requirements of your chosen variety.
• Cultivation method: Different substrates are suitable for hydroponics, aeroponics or cultivation in pots.
• Experience: Soil is often the best choice for beginners as it is forgiving of watering mistakes.
• Budget: The prices for substrates vary greatly.
• Environmental compatibility: Look for sustainable substrates such as coconut fibers.

Mixing substrates: Individual solutions

You can mix different substrates to optimize the properties and create an individual substrate. Here are a few examples:

• Soil-coconut mix: Combines the nutrient supply of the soil with the good aeration of the coconut fibers.
• Soil-perlite mix: Improves drainage and aeration of the soil.
• Coconut-perlite-vermiculite mix: Ideal for hydroponics and plants with high water requirements.

Conclusion

The right substrate is crucial for successful indoor growing. It influences the nutrient supply, water availability and the health of the plants. The choice of the optimal substrate depends on various factors, such as the type of plant, the cultivation method and your personal preferences. Find out about the different options and experiment to find the best solution for your plants.