1. Appearance:
Raw perlite is black or gray, but after processing, it turns a bright white due to its expanded, porous structure.
2. Expansion Process:
When perlite is heated to around 1,000°C (1,832°F), the trapped water vaporizes, causing the material to expand up to 20 times its original volume.
3. Porous Structure:
The heating process gives perlite a unique, lightweight, and porous structure, which makes it ideal for water retention and aeration in soils.
4. pH Neutral:
Perlite has a neutral pH of around 7, meaning it doesn’t alter the acidity of the soil it’s mixed into.
5. Reusability:
Perlite is inert, so it can be reused in gardening and horticulture after being sterilized.
6. Natural Insulator:
Expanded perlite has excellent insulation properties and is often used in construction to insulate walls, floors, and roofs.
7. Water Retention:
Perlite can hold up to four times its weight in water, which helps keep roots moist while allowing for excellent drainage.
8. Good Drainage:
Its porous nature improves soil aeration and drainage, preventing waterlogging in soil mixes.
9. Lightweight:
Expanded perlite is extremely lightweight, making it easy to handle and reducing the weight load in potted plants or roof gardens.
10. Odorless:
Perlite is completely odorless, which makes it a pleasant addition to indoor potting mixes.
11. Pest-Resistant:
Perlite doesn’t provide nutrients or organic matter for pests, so it’s resistant to infestation.
12. Sterile Material:
It’s sterile and free from weed seeds, diseases, or pests, which is ideal for starting seeds and propagating plants.
13. Recyclable:
Perlite is a recyclable material, making it an eco-friendly choice for horticulture and construction.
14. Aeration Properties:
It helps maintain soil aeration, which is essential for healthy root growth and oxygen exchange.
15. Chemically Inert:
Perlite doesn’t react chemically with other substances, which makes it stable and non-reactive.
16. Nutrient-Free:
Unlike soil, perlite doesn’t contain any nutrients on its own, so it’s usually mixed with other media that provide nutrients.
17. Hydroponic Uses:
Perlite is commonly used in hydroponics as a soil alternative due to its water retention and aeration capabilities.
18. Low Cation Exchange Capacity (CEC):
Perlite has low CEC, meaning it doesn’t hold onto nutrients, making it a better additive than a stand-alone medium.
19. Origins in Nature:
The formation of perlite dates back millions of years, originating from volcanic activity.
20. Temperature Tolerance:
It has a high melting point and doesn’t decompose at high temperatures, making it suitable for various industrial applications.
21. Environmental Impact:
Extracting perlite has a low environmental impact compared to other mined minerals.
22. Fire Resistant:
Perlite is fire-resistant, which is why it’s often used in fireproofing applications in construction.
23. Soundproofing:
It is also used in soundproofing applications due to its porous structure.
24. Widely Found:
Major perlite deposits are found in the USA, Greece, Turkey, and Japan. At SA Horticulture, we use South African mined perlite.
25. Seed Starting:
It’s a popular medium for seed starting as it provides the right moisture retention and drainage balance. Ideally, perlite should be mixed with coco peat, not used on its own.
26. Available in Grades:
Perlite is available in fine, medium, and coarse grades. We use medium grade perlite in horticulture.
27. Hydrophobic Nature:
Expanded perlite is hydrophobic initially but will absorb water over time, which helps in evenly distributing water in soil mixes.
28. Affordable:
Perlite is relatively inexpensive and readily available, making it accessible to gardeners and horticulturists.
29. Breathable Soil:
It improves soil aeration, which is essential for preventing root rot in potted plants.
30. Alternative to Sand:
In potting mixes, perlite often serves as an alternative to sand for improving drainage.
31. High Porosity:
Perlite’s porosity means it creates spaces in soil for oxygen, critical for root and plant health.
32. Light Reflectivity:
Perlite reflects light, helping reduce soil temperature and potentially enhancing plant growth. It’s an ideal as a soil topping for indoor plants or in the greenhouse.
33. Construction Applications:
Beyond horticulture, perlite is used in cement, plaster, and other building materials to enhance insulation.
34. Neutral TDS:
Perlite doesn’t contribute to total dissolved solids (TDS) in water, making it a stable substrate for sensitive plants.
35. Non-Decomposing:
Perlite doesn’t decompose over time, maintaining its structure and properties for long-term use in soil.
36. Erosion Control:
It is used in landscaping to control erosion by enhancing soil structure and reducing compaction.
37. pH Stabilizer:
Perlite doesn’t affect pH levels and acts as a stabilizer in pH-sensitive environments.
38. High Silica Content:
It contains about 70-75% silica, which is essential in many industrial and agricultural processes.
39. Doesn’t Compact:
Unlike organic materials, perlite doesn’t compact, keeping soil light and fluffy.
40. Enhanced Root Growth:
By improving aeration and drainage, perlite promotes stronger and healthier root systems.
41. No Nutrient Leaching:
Perlite doesn’t retain fertilizers, so nutrients reach the plant roots effectively without build-up.
42. Safe for Aquatic Plants:
It’s often used for aquatic plants as it provides stability without altering water chemistry.
43. Long Lifespan:
Perlite’s structure is resilient and doesn’t degrade over time, providing a lasting soil amendment.
44. Resists Algae Growth:
Perlite resists algae growth in its particles, keeping soil free from contamination.
45. Protects Seeds:
It helps protect seeds during germination by providing moisture and temperature regulation.
46. Used in Succulent Mixes:
Perlite is popular in cactus and succulent soil mixes due to its excellent drainage properties.
47. Widely Adaptable:
Whether in hot or cold climates, perlite maintains its structure and function, making it adaptable for diverse environments.