Classification and Analysis of Growing Media

Growing media available on the market can generally be divided into three main categories: soil media, plant-based media, and gravel media. Below is a detailed analysis of each type.

1. Soil Media

1.1 Akadama

Akadama is a soil medium formed from volcanic ash, widely used in horticulture and aquascaping, often referred to as “red clay.” It can serve as a base growing medium or be mixed with other media to enhance cultivation effects.

• Source: Volcanic ash from the Kanto region of Japan.
• Characteristics: Dark red or yellow granules, slightly acidic, excellent aeration and drainage, effectively retains moisture.
• High Permeability: Ensures healthy root systems due to its excellent aeration.
• Granular Consistency: Uniform granules with moderate weight and good stability.
• Drainage Effect: Provides good drainage whether used alone or mixed with other media, preventing root rot.
• Moisture Retention: Effectively retains moisture, especially suitable for succulent plants.
• Hygienic: Free from harmful bacteria, ensuring safe cultivation.
• pH Level: Slightly acidic, suitable for a variety of plants.
• Suitable Plants: Ideal for most plants, especially potted varieties.

Advantages:

• Excellent drainage prevents root rot.
• Good moisture retention, suitable for succulents and cacti.

1.2 Kiryu Soil

• Main Source: Tochigi Prefecture, Japan.
• Advantages:
  • Soft Texture: Effectively retains moisture and nutrients, promoting root development.
  • Longevity: Breaks down slower than Akadama, suitable for surfaces, maintaining stability over time.
  • Color: Light yellow, appealing to gardeners who prefer a subtle style.
• Characteristics: Brownish-yellow, good aeration and moisture retention, strongly acidic.
• Coarse Pores: Distinct pore structure, elastic, suitable for weaker-rooted plants (like succulents).
• Composition: Contains more calcium oxide, highly acidic, should be used cautiously to avoid soil imbalance.
• Suitable Plants: Acid-loving plants like azaleas and camellias.

Mixing Akadama and Kiryu: Combining Akadama and Kiryu can leverage the strengths of both. Akadama’s quick water absorption complements Kiryu’s moisture regulation, aiding in water control and preventing early breakdown of Akadama.

1.3 Kiryū Sand

• Source: Volcanic sand from Kiryu City, Japan.
• Characteristics: Gray, hard, not easily crushed, weakly acidic.
• Suitable Plants: Ideal for succulents and alpine flowers.

1.4 Tanshan Stone

• Source: Artificially fired stone.
• Characteristics: High porosity, slightly alkaline.
• Suitable Plants: Suitable for cacti and orchids.

1.5 Peat Soil

• Source: Organic matter formed from long-term decomposition of plants in wetlands.
• Characteristics: High organic matter content, excellent moisture retention, slightly acidic.
• Advantages:
  • Good nutrient retention, releasing nutrients over time.
  • Good temperature regulation.
• Disadvantages:
  • Poor drainage, prone to waterlogging.
  • Not suitable for succulents, needs to be mixed with other media.

2. Plant-Based Media

2.1 Sphagnum Moss

Sphagnum moss is made from dried mosses found in forests or wetlands. It has outstanding moisture absorption, capable of holding 20 times its weight in water, and offers good drainage. It is commonly used for orchids and staghorn ferns and is a primary material for making Kokedama (moss balls). High-quality sphagnum is clean, free of impurities, and can last 2-5 years.

• Source: Mosses from high-altitude areas.
• Advantages:
  • Excellent water retention, suitable for orchids.
  • Free from pests and diseases, reducing plant health risks.
  • Natural antibacterial properties, creating an acidic environment that inhibits pathogens.
  • High aeration, preventing waterlogging.
  • Soft and resilient, stabilizing root systems, beneficial for delicate plants like orchids.
• Disadvantages:
  • Requires frequent watering, as it dries quickly.
  • Fibers may break down over time, reducing aeration.
  • Needs regular repotting to remove decomposed sphagnum.

2.2 Snake Wood Chips

• Source: Dried branches of ferns.
• Characteristics: Black fibrous, good drainage and aeration.
• Suitable Plants: Ideal for orchids and climbing plants, recommended to mix with other media.

2.3 Coconut Fiber (Coir)

Coconut coir and shell are materials processed from coconut husks. The main difference is:

• Coir Pith: Finer granules, excellent water retention.
• Coconut Shell: Coarser granules, better aeration.

Mixing coconut coir and shell can enhance growth conditions for various plants due to their complementary properties.

2.4 Bark

Bark from trees is cut into small pieces and dried, mainly used for orchid cultivation. Pine bark has been widely used since 1960 as a single or mixed growing medium and as a soil cover to maintain soil health.

• Source: Bark from North American trees.
• Characteristics: Attractive appearance, fibrous and resilient.
• Benefits: Provides stable support for air-rooted orchids, retains soil structure, suppresses weed growth, and enriches soil with nutrients.

3. Gravel Media

3.1 Mountain Sand

• Characteristics: Good aeration, not easily crumbled.

3.2 Fuji Sand

• Source: Volcanic sand from around Mount Fuji.
• Characteristics: Good moisture retention and drainage, often mixed with Akadama.

3.3 Volcanic Rock/Pumice

• Characteristics: Lightweight, porous, mineral-rich, widely used in horticulture and landscaping.
• Benefits:
  • Excellent drainage, reducing root rot risk, especially for succulents and cacti.
  • Improves soil aeration, promoting healthy growth.
  • Rich in minerals, providing long-lasting nutrition.

3.4 Perlite

Perlite is an acidic volcanic glass that expands when heated. It is used for seedling and various flowering plants, especially crucial for plants like African violets.

• Characteristics: Clean, sterile, neutral pH, excellent aeration.
• Advantages: Lightweight, economical, and improves drainage.

3.5 Vermiculite

Vermiculite is a layered product from mica, widely used in plant cultivation, especially for rooting or potting orchids.

• Characteristics: Lightweight, porous, excellent moisture and nutrient retention.
• Advantages: Clean, sterile, promotes healthy root development, and provides essential nutrients.

3.6 Other Media

• Charred Rice Husk: Enhances plant disease resistance and improves soil structure.
• Bamboo Charcoal: Absorbs harmful substances in water, releasing trace elements.
• Green Zeolite: An aluminosilicate mineral effective in soil improvement, enhancing the growth environment for plants.

Conclusion

Choosing the right growing medium is crucial for healthy plant growth. Each medium has its characteristics and suitable uses. Selecting appropriate media based on plant needs and cultivation environments can effectively enhance plant growth performance and ensure healthy potted plants.