Which is better for aeration: perlite or vermiculite?
Written by
Tina Carter
Reviewed by
Prof. Charles Hartman, Ph.D.It is essential to distinguish between perlite and vermiculite, as this can help optimize soil aeration according to the specific needs of different plants. Perlite, composed of irregular structures of volcanic glass, creates permanent air pockets for long-term help with aeration; vermiculite, which you may find in layered form from minerals derived from mica, will pack down over time. Select the one that best matches the drainage and moisture requirements of your plants and soil to help aid in root health and healthy growth.
Perlite Properties
- Irregular porous structure maintains air pockets indefinitely
- Neutral pH doesn't alter soil chemistry
- Ideal for cacti and plants needing fast drainage
- Add 25-30% volume to potting mixes
Vermiculite Properties
- Layered mineral structure holds water like a sponge
- Provides magnesium and potassium nutrients
- Suitable for moisture-loving plants like ferns
- Use 15-20% in seed-starting mixes
Application Techniques
- Mix perlite throughout soil for even distribution
- Layer vermiculite below root zones in containers
- Combine with compost for balanced structure
- Replenish annually as materials break down
If you find yourself working with clay soils that are cumbersome or with moisture-sensitive plants, perlite is the ideal solution. Its naturally aerated structure makes it an optimal choice because the pores in the structure inhibit compaction in both containers and raised vegetable beds. If working with sandy soils that require moisture retention, then vermiculite can be a valuable option - it provides a better water-holding capacity while still retaining air space and promoting dormancy.
For general gardening purposes, combine both amendments for balanced results. Mixing two parts perlite with one part vermiculite for potting mixes will provide aeration and moisture. For the best results, observe plant performance and adjust (within seasonal changes) the ratio of these amendments as needed.
Avoiding dust inhalation when handling perlite is critical, so moisten it before mixing. Vermiculite absorbs moisture best when pre-soaked. A little preparation is all that is required for these great soil amendments to be effective and safe to use.
Read the full article: How to Aerate Soil Like a Pro
