Type: Tender Perennial (grown as annual) • Family: Convolvulaceae (Morning Glory) • Sun: Full sun (8+ hours) • Water: Moderate (reduce as roots mature) • Soil pH: 5.5-6.5 • Hardiness: Very tender—need 4 months frost-free
Planting Calendar (Zone 6b/7a)
| Method | Timing | Notes |
|---|---|---|
| Start indoors | February - March (grow slips) | Suspend root half in water, or lay on moist soil. Slips (shoots with roots) form in 3-6 weeks. Each root produces 10-20+ slips. |
| Direct sow | N/A—grown from slips | Sweet potatoes are grown from vegetative slips, not seed. |
| Transplant | May 20 - June 10 | Plant slips 3-4" deep, 12-18" apart in raised ridges (ridges warm soil and improve harvest). After all frost danger and soil 65°F+. |
| Days to maturity | 90-120 days from slip planting | |
| Succession plant | N/A—single planting |
Expected Yield
- Per plant: 1-3 lbs per plant (2-6 roots)
- Per 10' row: 15-30 lbs per 10' row
- Per season: 20-40 lbs per 10' row
Growing Conditions
- Soil: Well-drained, sandy loam preferred. Moderate fertility—too rich = huge vines, few roots. Raised ridges essential. pH 5.5-6.5 (more acidic than most crops).
- Fertilizer: Light feeder. Avoid nitrogen—lush vines, poor root development. Compost at planting usually sufficient. Low nitrogen, moderate P and K.
- Companions: Beans, okra, peppers, marigolds (nematode control), nasturtiums
- Avoid: Squash (vine competition), heavy nitrogen feeders
- Pests: Sweet potato weevil (not common in WV), flea beetles, wireworms (in newly turned sod), deer (fence). Generally pest-resistant.
- Diseases: Root rot (well-drained soil essential), scurf (certified disease-free slips, rotate 3+ years), black rot. Marigolds as pre-crop reduce nematodes.
Heirloom & Recommended Varieties
'Beauregard'
The standard since 1987. 2-3 lb roots. Very productive. Good keeper. Excellent flavor. Most reliable in WV.
'Centennial'
The other standard. Red skin, orange flesh. Very sweet. Good for baking. Stores well.
'Georgia Jet'
Very productive—some report 2x Beauregard yield. Good for shorter seasons. Vigorous vines.
'O'Henry'
White-fleshed. Creamy, nutty, like a cross between potato and sweet potato. Less sweet, more versatile.
'Murasaki-29'
Japanese-type. Purple skin, dry white flesh. Nutty, chestnut-like flavor. Less sweet. Premium market variety.
Cultural History & Domestication
Sweet potatoes originated in Central or South America, cultivated 5,000+ years ago. They are unrelated to yams (Dioscorea from Africa/Asia)—true yams are rarely grown in the US. Columbus brought them to Europe, and they spread to Africa and Asia via Portuguese traders. The confusion between sweet potatoes and yams in American grocery stores has colonial-era roots—enslaved Africans called sweet potatoes 'yams' because they reminded them of the African yam.
Seed Saving
Sweet potatoes are vegetatively propagated—slips from stored roots. Save the best roots from harvest (no cuts or damage), cure them, and store at 55-60°F with high humidity. In late winter, grow slips for next season. No cross-pollination concerns since propagating vegetatively. Select roots from most productive, disease-free plants.
The Loop Farmstead Standard
- Compost: 1-2 inches annually (on-farm production)
- Cover crops: Rye + vetch (fall), buckwheat (summer), daikon (compaction)
- Wood chips: Pathways only (aged 2+ years for beds)
- Fall leaves: Mulch or compost browns
- Blood/bone meal: From farm-slaughtered animals
- Biochar: Charged with compost tea (permanent carbon)
- Wood ash: Light application from wood stove
- Eggshells: Crushed/powdered (slow calcium)
Never used: Synthetic fertilizers, mined minerals, gypsum, peat moss