What soil mix works best in containers?
Written by
Olivia Mitchell
Reviewed by
Prof. Charles Hartman, Ph.D.The ideal soil mixture for container spinach consists of a 70% potting soil and 30% compost blend, creating a balanced, nutrient-rich, and well-draining mix. This mixture is designed to prevent soil compaction while providing essential nutrients to the soil. Avoid using garden soil, as it tends to compact, which prevents roots from growing and hinders drainage in containers.
Base Ingredients
- 70% quality potting mix for structure and aeration
- 30% mature compost for slow-release nutrients
- Optional: 10% perlite for heavy clay soils
- Optional: 5% worm castings for microbial activity
Nutrient Balance
- Maintain pH 6.0-7.0 for nutrient availability
- Add lime if pH drops below 6.0
- Mix in bone meal for phosphorus needs
- Avoid high-phosphorus fertilizers that trigger bolting
Evaluate the drainage capacity prior to planting. Saturate your mix and wait for 30 seconds. If pooling occurs, add more perlite to improve drainage. Proper drainage helps prevent root rot (which can kill spinach faster than nutrient deficiencies).
Maintain a pH balance between 6.0 and 7.0 for optimal nutrient absorption. Test the soil every 4 weeks using simple test strips. If pH drops below 6.0, add garden lime. If it rises above 7.0, add sulfur to avoid iron lockout.
Renewing soil between plantings entails removing the top 2 inches of soil and replacing it with fresh compost mix. After every three cycles, replace all soil to prevent disease buildup. Container soils deplete quickly than garden beds and need more frequent replenishment of soil.
Read the full article: How to Grow Spinach in Containers Successfully
