Growing Sweet Potatoes in Raised Beds: Soil Depth, Amendments, and Spacing

Raised beds are ideal for sweet potatoes, especially in regions with heavier soils or shorter growing seasons. Over decades of growing sweet potatoes in Sonoma Valley, I’ve found that proper soil depth, organic amendments, and spacing make the difference between small roots and large, sweet, well-formed tubers. This experience-based guide shows exactly how to set up raised beds for optimal sweet potato growth.

Table of Contents

1. Ideal Soil Depth

Sweet potatoes develop underground tubers that need loose, friable soil.

Minimum depth: 10–12 inches
Optimal depth: 12–18 inches for large, unbroken tubers
Why it matters: Shallow soil restricts tuber expansion, leading to misshapen or stunted roots

Experience Tip:
I build raised beds 12–18 inches high and fill them with a mix of native soil, compost, and coarse sand for deep, well-drained beds.

2. Soil Amendments for Raised Beds

Sweet potatoes thrive in nutrient-rich, loose soil. Essential amendments include:

Compost: 2–3 inches incorporated into topsoil
Organic fertilizers: Low-nitrogen balanced options, such as 4-4-4 or fish meal
Phosphorus sources: Bone meal or rock phosphate to encourage root development
Potassium sources: Kelp meal or greensand to improve tuber size and flavor

My Insight:
Through decades of hands-on practice, I’ve observed that raised beds amended with compost, phosphorus, and potassium consistently produce larger tubers than unamended beds.

3. Soil Preparation Steps

Loosen soil to 12–18 inches with a garden fork or broadfork
Incorporate amendments evenly throughout the bed
Form mounded rows if your soil is heavier or compacted
Level the surface for even planting

Experience Tip:
Mounding slightly improves drainage and warms the soil earlier in spring, which encourages tuber initiation.

4. Plant Spacing in Raised Beds

Proper spacing prevents crowding and allows tubers to grow large:

Between slips: 12–18 inches apart
Between rows: 3–4 feet for vining varieties
For containers: 1–2 slips per 12–15 inch container

Experience Tip:
I space plants generously in raised beds; crowded vines produce smaller, misshapen tubers and limit airflow, increasing disease risk.

5. Companion Tips for Raised Bed Sweet Potatoes

Mulch with straw or leaves after slips root to retain moisture and suppress weeds
Water deeply and consistently, especially during tuber bulking
Monitor for pests such as weevils and aphids, which can reduce yield

Experience Tip:
Raised beds warm quickly and drain well, reducing pest and disease pressure compared with in-ground plantings in clay-heavy soil.

Final Thoughts

Growing sweet potatoes in raised beds is a proven way to produce large, sweet, healthy tubers. Focus on adequate soil depth, rich organic amendments, proper spacing, and thoughtful bed preparation, and your raised beds will reward you with a bountiful harvest.

From my decades of hands-on experience, raised beds provide better drainage, easier soil management, and higher yields than traditional in-ground rows, making them ideal for home gardeners and small-scale growers alike.