Potato Container Soil Mix
Solanum tuberosum
Acidic, low-N container mix for potatoes — the yield driver is the hilling technique, not the soil composition.
- Container:
- 15+ gallon fabric grow bag (5 gal soil per plant)
- pH:
- 4.8–5.5
- EC:
- 1.5–2.5 mS/cm
- Sun:
- 6–8 hr
Components
Percentages by volume. Quantities scaled for a 15-gallon container (US units).
| Component | % | Amount |
|---|---|---|
| Quality potting mix Base structure, initial nutrients | 40% | 24 qt |
| Coco coir (low-EC, buffered) CEC, moisture buffering | 20% | 12 qt |
| Aged compost Microbial diversity | 20% | 12 qt |
| Perlite Drainage, aeration
Alternates: Pumice | 15% | 9 qt |
| Charged biochar Long-term CEC, nutrient retention | 5% | 3 qt |
Per-container amendments
Scaled linearly to your container size. Apply at transplant or as side-dress per the notes on each line.
- 5-10-10 or 5-10-5 (low-N, high P/K) 5-10-10 or 5-10-5 (low N, high P/K).1 cup
- 2 tbsp
- Mycorrhizae inoculant At planting.1 tbsp
Growing notes
- Acidic mix (pH < 5.5) suppresses scab, the most common potato disease in containers.
- Hilling method: fill the bag 1/3 full, plant 3" deep, then add mix to bury the lower 2/3 of the stem as shoots grow 8". Each buried stem section produces more tubers.
- 5 gallons of soil per plant. Crowding reduces yield more than any other factor.
- NEVER reuse the mix for potatoes, tomatoes, peppers, or eggplant — they share soil-borne diseases (Streptomyces scabies, Phytophthora).
- In hot zones (8-10), plant fall through late winter — tuber formation needs night temps below ~68F.
- Use an acid-formulated potting mix, OR add elemental sulfur to lower pH (slow — apply weeks ahead).
- NO fresh manure (causes scab disease).
Want to scale this to a different container size, save it to a plot plant, or track applied dates? Open it in the interactive calculator.
References
- Container potato guides: pH 4.8-5.5; >6.5 increases scab; 5 gal soil/plant — University extension (multiple)
- Fabric grow bag air-pruning improves root structure; hilling drives tuber multiplication — Smart Pot / Gardener's Supply