The right substrate is an essential part of successful houseplant care. It provides the foundation for plant growth and health by giving them support, storing water, and providing necessary nutrients. Different types of plants have specific requirements for their substrate, and understanding these requirements can make the difference between a thriving plant and one that vegetates.
What is substrate?
Substrate is the material in which plants are planted. It serves as an anchor for the roots and as a medium that stores water and nutrients. In horticulture and plant care, the substrate is selected specifically for the needs of the particular plant in order to create optimal growing conditions. There are many different types of substrate, each with different properties and suitable for different types of plants.
Difference between soil and substrate
While the terms "soil" and "substrate" are often used interchangeably, there is an important difference. Soil typically refers to naturally occurring soil found outdoors that contains a mixture of organic material, minerals, water, and air. Substrate, on the other hand, is often a specially formulated mix designed for use in pots and containers. It may contain soil, but is often enriched with additional materials to improve certain properties, such as drainage, air circulation, and nutrient retention.
functions of the substrate
The substrate has several important functions:
- Anchoring: It provides support and stability to the roots of the plant.
- Water storage: The substrate stores water, which is absorbed by the roots.
- Nutrient supply: It contains nutrients necessary for the growth of the plant.
- Aeration: It allows the roots to access oxygen, which is essential for their health.
- Drainage: It ensures that excess water can drain away to prevent waterlogging and root rot.
Types of substrates and their properties
There are many different types of substrates, each with different properties and suitable for different types of plants. Some of the most common substrates are:
Potting soil
Potting soil is the most common substrate for houseplants. It is usually made from a mixture of peat, compost, bark and sometimes sand or perlite to improve drainage. Potting soil is versatile and suitable for most houseplants.
- Characteristics: Good water retention, good nutrient supply, medium drainage.
- Suitable for: Most houseplants, especially non-succulent plants.
cactus soil
Cactus soil is a special substrate designed for cacti and other succulents. It has very good drainage and often contains coarse materials such as sand, perlite or fine pebbles to ensure that excess water drains away quickly and the roots do not rot.
- Properties: Excellent drainage, low water retention, no waterlogging.
- Suitable for: cacti, succulents and other drought-loving plants.
orchid substrate
Orchid substrate is specially designed for epiphytic orchid species such as Phalaenopsis and Cattleya. These plants grow on trees in nature and require a substrate that allows good aeration of the roots. Orchid substrate is often made of coarse materials such as pieces of bark, charcoal, perlite and sometimes coconut fiber.
- Properties: Very good ventilation, low water retention, loose structure.
- Suitable for: Epiphytic orchids, some bromeliad species.
potting soil
Potting soil, also known as seed compost, is a substrate specifically designed for growing seeds and cuttings. It is lightweight and often contains little to no nutrients so as not to affect germination. It is typically made of peat, sand or perlite, and sometimes vermiculite.
- Characteristics: Light, good drainage, low in nutrients.
- Suitable for: sowing seeds, growing cuttings.
peat moss
Peat moss, especially sphagnum peat moss, is often used as an additive in substrate mixes to improve water retention. It is also commonly used as a main ingredient in substrates for carnivorous plants that prefer very nutrient-poor but moist conditions.
- Characteristics: Excellent water retention, low nutrients, slightly acidic.
- Suitable for: Carnivorous plants, orchids (as an additive), cultivation.
hydroponic substrate
Hydroponics, a method of plantless cultivation, does not use a traditional substrate. Instead, plant roots are placed in an inert medium such as expanded clay, perlite or rockwool, which supports the plant while providing water and nutrients delivered directly to the root zone.
- Properties: Inert, no nutrients, excellent drainage.
- Suitable for: Hydroponic systems, plants with special requirements.
coconut fibers
Coconut fiber, also known as coir, is a sustainable substrate obtained from the husk of coconuts. It has similar properties to peat, but is renewable and more environmentally friendly. Coconut fiber retains water well, has good aeration and contains no nutrients.
- Features: Good water retention, renewable, good aeration.
- Suitable for: Many houseplants, especially tropical plants.
composition of substrate mixtures
Many substrates are mixtures of different components to achieve specific properties that are ideal for the particular plant. The composition of a substrate mixture can vary depending on the desired water retention, drainage, nutrient supply and aeration.
peat
Peat is a widely used component of substrates. It is organic, retains water well and improves the structure of the substrate. However, peat is not renewable and its extraction can be harmful to the environment. Therefore, alternatives are increasingly being sought.
Perlite
Perlite is a volcanic rock that is heated and expanded to create a lightweight, porous material. It is often used in substrate mixes to improve drainage and loosen the substrate.
vermiculite
Vermiculite is a mineral that expands in a similar way to perlite. It retains water and nutrients well and is often used in substrates for plants that require consistent moisture.
compost
Compost is organic material consisting of decomposed plant waste. It is rich in nutrients and improves the structure of the substrate. Compost is often added in small amounts to substrate mixtures to increase fertility.
sand
Sand is often used to improve drainage in substrates. Sand is an important component, especially in cactus and succulent substrates. It ensures that the water drains away quickly and the roots do not remain wet for too long.
bark
Bark, especially pine bark, is often used in orchid substrates. It provides a loose structure that allows good aeration of the roots. Bark can also be used in other substrates to improve drainage.
Choosing the right substrate for different plant species
Choosing the right substrate is crucial for the health and growth of houseplants. Different plant species have different requirements for their substrate, based on their natural habitat and specific needs.
Tropical plants
Tropical plants such as Monstera, Philodendron and Anthurium require a substrate that retains water well but at the same time provides good drainage. A mixture of potting soil, perlite and some compost is ideal for these plants.
succulents and cacti
Succulents and cacti require a substrate with excellent drainage as they are susceptible to root rot. Cactus soil or a mixture of potting soil, sand and perlite ensures that water drains quickly.
orchids
Epiphytic orchids require a very loose substrate that allows good aeration of the roots. A mixture of coarse bark, charcoal and perlite is ideal for these plants.
Carnivorous plants
Carnivorous plants such as Venus flytrap and sundew require an acidic, nutrient-poor substrate that retains moisture well. A mixture of peat moss and sand is ideal.
hydroponic systems
For plants in hydroponic systems, an inert substrate such as expanded clay or perlite is used. This substrate does not store water or nutrients, but only serves to stabilize the plant while the nutrient solution goes directly to the roots.
care of the substrate
The substrate of houseplants needs to be cared for regularly to ensure that it performs its function optimally. This includes regular repotting, renewing the substrate and checking for signs of problems such as compaction or mold.
repotting
Houseplants should be repotted regularly to renew the substrate and give the plants more space for root growth. Depending on the type of plant and growth rate, this should be done every one to two years.
renewal of the substrate
Over time, the substrate can lose its structure and nutrient content. This can lead to compaction, poor drainage and a lack of nutrients. If necessary, the substrate should be completely or partially renewed.
Check for compaction and mold
Compacted substrate can limit root ventilation and increase the risk of root rot. Mold formation on the surface of the substrate is a sign of excessive moisture or poor ventilation. In such cases, the substrate should be loosened or replaced.
