Okinawa Sweet Potato Slips: The Ultimate Guide to Growing, Caring & Harvesting

Have you ever seen those vibrant purple sweet potatoes and wondered how to grow them at home? You’re in the right place!

If you’re a fan of vibrant, nutrient-packed superfoods, Okinawa sweet potatoes might already be on your radar. These stunning purple-fleshed tubers have a rich history, incredible health benefits, and a unique flavor that makes them a favorite in both traditional and modern cuisine. But before you can grow your own, you’ll need Okinawa sweet potato slips.

Let’s dive into everything you need to know to successfully plant, care for, and harvest them.

What Are Okinawa Sweet Potato Slips?

Okinawa sweet potatoes, often mistaken for Japanese sweet potatoes, . These potatoes are packed with antioxidants, fiber, and vitamins[1]
, making them a staple in the Okinawan diet, which is known for longevity.

Sweet potato slips are small vine-like sprouts that grow from a mature sweet potato. Unlike regular potatoes, which are grown from tubers (seed potatoes), sweet potatoes are started from these rooted sprouts. They’re the key to propagating new plants and ensuring a successful harvest.

Okinawa sweet potatoes, sometimes called Hawaiian purple sweet potatoes but often mistaken for Japanese sweet potatoes, are a nutrient-packed variety originally from the Ryukyu Islands in Japan, originate from Japan’s Okinawa region.

Okinawa sweet potatoes are a stunning and flavorful variety, with creamy beige skin revealing vibrant purple-magenta flesh. Packed with anthocyanins, polyphenols, vitamin C, and soluble fiber, they’re as nutritious as they are beautiful. Thriving in warm climates, these sweet potatoes are an excellent choice for backyard gardeners looking for a hardy and rewarding crop.

Key Features of Okinawa Sweet Potatoes

Scientific Name: Ipomoea batatas ‘Okinawa’
Mature Size: Vines can spread 6-10 feet, with tubers growing underground
Cold Tolerance: Best suited for USDA Zones 9-11; needs warm temperatures to thrive
Ideal Planting Time: Spring to early summer, after the soil has warmed to at least 65°F (18°C)
Growth Rate: Fast-growing, with tubers ready for harvest in 90-120 days
Tuber Characteristics: Deep purple flesh with a mildly sweet, nutty flavor, rich in antioxidants
Invasiveness: Non-invasive, but vines can spread widely—best for raised beds or large containers
Growth Habit: Trailing vine with lush green foliage, ideal for ground cover or container gardening

Planting Okinawa Sweet Potato Slips

Choosing the Right Location

Okinawa sweet potatoes love the sun, so select a spot that gets at least 6-8 hours of direct sunlight per day. These heat-loving plants need warm soil to thrive, so if you’re in a cooler climate, consider using raised beds or black plastic mulch to help retain heat. If you’re planting in a region with a short growing season, starting them in containers can help extend their growing window.

Soil Preparation

To ensure your Okinawa sweet potatoes grow strong and produce an abundant harvest, soil quality is key. These plants do best in loamy, well-draining soil with a pH between 5.5 and 6.5. Avoid heavy clay soils, as they can cause root rot and stunt tuber development. If your soil is dense, mix in sand and organic compost to improve aeration and drainage.

Adding compost also provides essential nutrients, helping the slips establish quickly and grow vigorously. Sweet potatoes don’t require much nitrogen, but they love potassium and phosphorus, so consider adding wood ash or bone meal to boost their growth.

Planting the Slips in the Ground

Once your soil is prepped and warm enough (ideally above 65°F or 18°C), it’s time to plant your healthy Okinawa sweet potato slips. Follow these steps for success:

Dig small holes about 4 inches deep and 12 inches apart in rows that are spaced 3 feet apart to allow vines to spread.
Place each slip into the hole, covering the roots and the lower part of the stem while keeping the leaves above ground.
Firm the soil around each slip to provide stability and promote root development.
Water immediately after planting to help the slips settle in and reduce transplant shock.

Container Planting for Small Spaces

If you’re short on garden space, don’t worry—Okinawa sweet potatoes grow exceptionally well in containers! Using a 10-gallon grow bag or a large container at least 12 inches deep provides plenty of room for the tubers to develop.

When growing in containers:

Make sure your pot has good drainage holes to prevent waterlogging.
Fill it with a well-draining potting mix enriched with compost or aged manure for added nutrients.
Plant slips just as you would in the ground, covering the roots while leaving the leaves exposed.
Place the container in a warm, sunny location and water regularly, ensuring the soil stays moist but not soggy.

Growing Okinawa Sweet Potatoes

Once your Okinawa sweet potatoes are planted, proper care is essential to ensure a healthy, bountiful harvest. From watering and fertilizing to pruning and winter protection, here’s how to keep your plants thriving!

Watering

Consistent watering is key to growing healthy, well-formed sweet potatoes. To encourage strong root development, water deeply once a week, ensuring moisture reaches the tubers below the soil. However, be cautious—overwatering can lead to root rot, so allow the soil to dry slightly between waterings. If you’re growing in containers, check drainage to prevent soggy soil.

Fertilizing

Okinawa sweet potatoes don’t need heavy feeding, but the right nutrients can improve yield and quality. Apply a balanced organic fertilizer (10-10-10) every 3-4 weeks to support steady growth. For better tuber development, consider increasing potassium levels by adding wood ash, kelp meal, or a potassium-rich fertilizer. Avoid excessive nitrogen, as it encourages vine growth over root production.

Pruning & Pinching

Since Okinawa sweet potatoes are vigorous growers, their vines can spread rapidly. Trim back vines occasionally to redirect energy into tuber production, but don’t go overboard—leaves play a crucial role in photosynthesis, which fuels root growth. If vines start invading nearby plants, a light pruning session will help keep them contained without sacrificing yield.

Winter Care

These tropical tubers love the heat, so if you live in a colder climate, you’ll need to take precautions. The best option is to grow them in containers and bring them indoors when temperatures drop below 50°F (10°C). If growing in-ground, apply a thick layer of mulch (such as straw or dried leaves) to insulate the soil and protect the roots from frost.

Potting & Repotting

For container-grown Okinawa sweet potatoes, repot annually with fresh, nutrient-rich soil to ensure healthy tuber formation. Use a deep container with ample space to allow roots to expand. If your sweet potatoes seem stunted, upgrading to a larger pot can promote better growth and yield.

How to Propagate Okinawa Sweet Potato Slips

Want to grow your own Okinawa sweet potato slips instead of buying them? It’s easy, fun, and ensures you have the healthiest starts for your garden. Here’s a step-by-step guide to propagating your own slips at home.

Start with a healthy Okinawa sweet potato (organic is best, as some store-bought potatoes are treated to prevent sprouting). Using toothpicks, suspend the potato half-submerged in a jar of water, with the pointed end facing down.

Place the jar in a warm, sunny window where it gets plenty of indirect light. Sweet potatoes love warmth, so keeping them at 70-80°F (21-27°C) will speed up the sprouting process.
After about 2-3 weeks, you’ll start to see small leafy sprouts (slips) emerging from the top. These will continue to grow over the next few weeks.
Once the slips are about 5-6 inches long, carefully twist them off the potato or cut them near the base. Don’t worry—new slips will keep growing from the same potato!
Place the slips in a glass of fresh water, ensuring the bottom half is submerged. In just a few days, roots will start to form. Change the water every couple of days to keep it fresh.
Once the roots are about 1-2 inches long, it’s time to plant them! Choose a warm garden bed or deep container filled with loamy, well-draining soil. Bury the roots and lower stem while keeping the leaves above the surface.

How to Get Okinawa Sweet Potatoes to Bloom

Okinawa sweet potatoes are primarily grown for their nutritious, vibrant purple tubers, but did you know they can also produce flowers? While blooming is rare in home gardens, it’s possible under the right conditions.

When Do They Bloom?

Okinawa sweet potatoes belong to the morning glory family (Ipomoea batatas), so when they do bloom, they produce small, delicate purple or white flowers similar to morning glories. However, flowering is uncommon, especially if the plant is directing most of its energy toward tuber production.

How to Encourage Blooming

If you’re hoping to see flowers, try these tips:

Keep soil evenly moist but avoid overwatering, as soggy conditions can lead to root rot.
Provide full sun exposure, ensuring at least 6-8 hours of direct sunlight per day.
Limit nitrogen-rich fertilizers since excess nitrogen encourages vine growth at the expense of flowers. Instead, use a low-nitrogen, high-phosphorus fertilizer to support flowering.

Harvesting and Storing Okinawa Sweet Potatoes

Growing Okinawa sweet potatoes is rewarding, but knowing when and how to harvest them is key to getting the best flavor and storage life. Here’s what you need to know to ensure a successful harvest.

When to Harvest

Okinawa sweet potatoes take about 90-120 days to mature. A good sign that they’re ready is when the vines start yellowing and dying back. To check, carefully dig around the base of a plant and gently feel for the size of the tubers. If they’re large enough, it’s time to harvest.

How to Harvest

To avoid damaging the tubers, use a garden fork or spade to loosen the soil around the plant, rather than pulling the vines directly. Slowly lift the tubers out by hand, being careful not to bruise or cut them. Shake off any excess dirt, but don’t wash them yet—excess moisture can lead to rot.

Curing for Better Storage

Freshly harvested sweet potatoes need to cure to develop their sweet flavor and improve storage life. Place them in a warm (80-85°F), humid area for 7-10 days. This process helps toughen the skin and heal minor wounds. After curing, store them in a cool, dark place (55-60°F) where they can last for several months.

Troubleshooting Common Problems

Even though Okinawa sweet potatoes are relatively easy to grow, occasional issues can arise. From yellowing leaves to pest invasions, here’s how to identify and fix the most common problems.

Common Issues & Solutions

Yellowing Leaves – This is often caused by overwatering or poor drainage. To fix it, reduce watering and make sure your soil drains well. Raised beds or adding sand to heavy soil can help prevent waterlogging.

No Tubers Forming – If your vines are thriving but no tubers are developing, the culprit is likely too much nitrogen. Excess nitrogen promotes leafy growth at the expense of roots. Switch to a low-nitrogen, high-potassium fertilizer to encourage tuber production.

Wilting Plants – Underwatering or heat stress can cause plants to wilt. Sweet potatoes need deep, consistent watering, especially in hot weather. Applying a layer of mulch helps retain soil moisture and keeps roots cool.

Pests & Diseases

Sweet Potato Weevils – These pests can damage both vines and tubers. Use row covers to keep them away and rotate crops yearly to disrupt their life cycle.

Root Rot – Poor drainage can lead to fungal infections in the roots. Ensure well-draining soil and avoid overwatering to prevent this issue.

Aphids – These tiny sap-sucking insects can weaken your plants. Spray with neem oil or insecticidal soap to keep them under control. Introducing beneficial insects like ladybugs can also help.

FAQs About Okinawa Sweet Potato Slips

What makes Okinawa sweet potatoes different from regular sweet potatoes?
Okinawa sweet potatoes stand out with their vibrant purple flesh, thanks to their high anthocyanin content, a powerful antioxidant. They also have a nutty-sweet flavor that sets them apart from the typical orange varieties.

How long does it take to grow and harvest Okinawa sweet potatoes?
These sweet potatoes need about 90-120 days to fully mature. Warmer climates and well-draining soil can help speed up the process, while cooler conditions may extend the growing time.

Can I grow Okinawa sweet potatoes in a container?
Absolutely! A deep container (at least 12 inches deep) works well, as long as it has good drainage. Large grow bags or raised beds are also great alternatives for small-space gardening.

Where can I buy Okinawa sweet potato slips?
You can purchase slips from specialty gardening stores, online seed suppliers, or local nurseries. If you prefer a hands-on approach, you can also grow your own slips at home from a mature Okinawa sweet potato.

Final Thoughts

Growing Okinawa sweet potato slips is an exciting, rewarding, and nutritious endeavor!

Whether you’re planting them in a backyard garden or a container, following these simple steps will ensure a healthy harvest.Now that you know how to plant, care for, and harvest Okinawa sweet potatoes, are you ready to start your gardening journey? Happy planting!

References

Danahy, Anne. “7 Surprising Benefits of Purple Potatoes.” Healthline, November 20, 2019. Accessed February 12, 2025. https://www.healthline.com/nutrition/purple-potatoes#1-Highly-nutritious.