Sweet potatoes are a rewarding crop for home gardeners, providing a lengthy harvest of nutritious storage roots. Unlike standard potatoes, sweet potatoes (Ipomoea batatas) are grown from specialized sprouts called “slips.” This method ensures the plant grows true to the parent variety and promotes the development of the large storage roots. Successful cultivation relies on timing the planting to coincide with consistently warm soil and air temperatures, as this tropical vine cannot tolerate frost.
Preparing the Planting Site
Sweet potatoes thrive in conditions that mimic their warm-weather origins, making soil preparation crucial for tuber formation. The ideal growth medium is a loose, well-drained, sandy loam, which allows the storage roots to expand easily without becoming stunted or forked. A slightly acidic soil pH, ideally ranging from 5.5 to 6.5, is preferred for optimal growth and nutrient availability.
Before planting, create raised mounds or hills approximately 8 to 12 inches high and 12 inches wide. Building these mounds improves drainage and allows the soil to warm up faster. The soil temperature must consistently measure at least 60°F to 65°F at planting depth for the slips to survive and begin growth. Avoid incorporating excessive nitrogen-rich fertilizers, as this encourages leafy growth at the expense of root development.
Sourcing and Hardening Off Sweet Potato Slips
Sweet potato slips are the young, vine-like shoots that sprout directly from a mature sweet potato. Gardeners can acquire these slips through reputable nurseries or generate their own by sprouting a sweet potato indoors several weeks before the outdoor planting date. Regardless of their origin, the tender, newly rooted slips require a careful transition from their protected environment to the conditions of the outdoor garden.
This acclimatization process is known as “hardening off,” which reduces transplant shock. Over seven to ten days, the slips should be gradually introduced to direct sunlight and wind. Initially, place them in a shaded area for a few hours daily, slowly increasing sun exposure. This process strengthens the plant and ensures the slips are robust enough to withstand the garden environment upon planting.
The Step-by-Step Planting Process
Transplanting the slips should only occur once the threat of frost has completely passed. Planting on a cloudy day or in the late afternoon can help minimize transplant shock. To plant a slip, gently remove the lower leaves, leaving only the top few leaves exposed above the soil line.
The slip should be buried deeply, ensuring that at least two to three leaf nodes are covered by the soil, as new roots and storage roots will form at these nodes. Slips should be spaced 12 to 18 inches apart within the prepared mounds, with rows separated by about three to four feet to accommodate the sprawling vines. Immediately after placement, the soil around each newly planted slip must be firmed gently to remove air pockets. A deep watering is then necessary to settle the soil and fully hydrate the young plant’s root zone.
Establishing the Slips Post-Planting
The first week following transplanting is a delicate period focused on establishing a new root system. Keep the soil consistently moist during this time to encourage rapid development. Watering should be deep and frequent for the initial 7 to 10 days, helping the slips overcome transplant stress.
Once the plants show clear signs of new growth, typically indicated by perked-up leaves and the start of vine extension, the watering frequency can be reduced. Established sweet potatoes tolerate drier conditions, but consistent moisture is required for uniform root growth, approximately one inch of water per week through rainfall or irrigation. Early weed control is also necessary, but cultivation should remain shallow to avoid damaging the developing storage roots directly beneath the soil surface.