Sweet potatoes are a high-yielding crop, but success depends on providing enough space for their extensive root systems and sprawling vines. Unlike traditional potatoes, sweet potatoes are grown from vegetative cuttings called “slips,” and their edible portion is a storage root, not a true tuber. Correct planting distance is fundamental, as it dictates how effectively each plant gathers resources and how large its harvestable roots can grow, ensuring good air circulation and preventing overcrowding.
Preparing the Soil and Planting Slips
Proper soil preparation is necessary, as sweet potatoes require a loose, well-drained medium to form their roots. Sandy loam is the preferred soil type, offering low resistance and good aeration for root expansion. Growers with heavier, clay-rich soil often create raised beds or high ridges to improve drainage and help the soil warm up quickly. The soil temperature must be at least 60°F before planting.
A “slip” is a young sprout, typically 6 to 12 inches long, cut from a sprouted sweet potato. Slips are planted deep enough to bury the nodes, which are the points along the stem where new roots—and eventually, the sweet potatoes—will emerge. Planting on pre-formed ridges, about 8 to 12 inches high and 12 inches wide, is a common practice that sets the foundation for spacing.
Standard Spacing for Row Planting
For traditional row cultivation, two primary spacing measurements are considered: the distance between individual plants and the distance between the rows. The standard recommended in-row spacing is typically between 12 and 18 inches. This distance provides adequate room for the storage roots to swell and prevents intense competition for water and nutrients.
The second measurement is the between-row spacing, separating the center of one planting ridge from the next. Sweet potato vines spread aggressively, often trailing 3 to 5 feet, requiring wide spacing to accommodate this growth. A standard distance of 3 to 4 feet (36 to 48 inches) between rows is recommended. This wide spacing ensures mature vines do not choke the space and helps improve air circulation, reducing the risk of fungal diseases.
How Spacing Affects Tuber Size and Yield
Adjusting the standard in-row spacing directly affects the size and total quantity of the harvest. Closer planting distances increase the plant population per square foot, leading to a higher total number of tubers harvested.
Tightening the in-row spacing to 8 to 10 inches results in a greater overall yield but produces significantly smaller individual tubers, often desirable for “fingerling” sizes. This higher density increases resource competition, restricting root growth. Conversely, widening the in-row spacing to 20 to 24 inches lowers the total harvest yield. However, the remaining plants face less competition, allowing each root to expand into larger, “jumbo” sized sweet potatoes.
Adjusting Spacing for Raised Beds and Containers
In raised beds, where soil quality and feeding are highly controlled, spacing can be slightly tighter, such as 9 to 12 inches apart, especially if the soil is loose and sandy. This closer spacing is often used in square foot gardening. The increased plant density must be managed with careful watering and nutrient application to prevent resource depletion.
For container growing, the vessel size must be substantial to allow room for the storage roots to form. A common recommendation is to plant a single sweet potato slip in a container holding at least 10 gallons of soil. Smaller containers, such as 5-gallon buckets, may only yield one or two usable sweet potatoes. A 15 to 20-gallon container is often suggested for optimal results, as the restriction can encourage the development of larger individual tubers.