← Plant Guides

How to Grow Hawaiian Purple Sweet Potato

Wikimedia Commons

Hawaiian Purple Sweet Potato

Ipomoea batatas 'Hawaiian Purple'

vegetable

Hawaiian Purple is a cultivar of sweet potato with striking deep purple flesh and skin, rich in anthocyanins and antioxidants. This warm-season vine produces abundant tubers and is highly ornamental with its burgundy foliage. It thrives in tropical and subtropical climates but can be grown in temperate regions with proper timing.

When should you plant Hawaiian Purple Sweet Potato in your zone?

Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.

Get my Hawaiian Purple Sweet Potato timeline →

Example Hawaiian Purple Sweet Potato timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Hawaiian Purple Sweet Potato

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Hawaiian Purple Sweet Potato

    Around Jul 26

    ≈ 100 days after planting

Sample dates for Pittsburgh, PA. Sign up to get exact Hawaiian Purple Sweet Potato dates for your own zip code.

Growing Conditions

☀️
Sun: Full sun, 6-8 hours daily minimum; 8+ hours preferred for best tuber development
💧
Water: Moderate water needs; keep soil consistently moist but not waterlogged during growing season. Reduce watering as harvest approaches. Drought-tolerant once established but produces better yields with regular moisture.
📏
Spacing: 12 inches
📅
Days to maturity: 100-150 days
🌱
Planting depth: 1-2 inches for slips (rooted shoots); plant whole tubers 4-6 inches deep

Soil

Type: Well-draining sandy loam or loamy soil with good organic content
pH: 5.8-6.2
Amendments:
Compost or aged manure Perlite or coarse sand for drainage Potassium-rich fertilizer

Growing Zones

Find your zone →

Zones 9-11; can be grown in zones 7-8 with season extension and careful timing

9a 9b 10a 10b 11a 11b

Sign up free to see if Hawaiian Purple Sweet Potato grows in your zone — and get a personalized planting timeline.

Get my Hawaiian Purple Sweet Potato timeline →

Growth Stages

1

Slip Production

6-8 weeks

Sweet potato tubers sprouted in warmth and moisture to produce rooted shoots (slips). Slips develop small leaves and root systems ready for transplanting.

Start tubers indoors 6-8 weeks before last frost. Keep in warm location (75-80°F) with high humidity. Use a propagation medium of sand or peat moss. Slips are ready when 6-9 inches tall with several roots.

2

Establishment

3-4 weeks

Young slips are transplanted into garden soil or containers. Plants develop a strong root system and initial vine growth. Purple foliage becomes visible.

Transplant after all frost danger has passed and soil is warm (60°F+). Keep consistently moist but not soggy. Provide full sun and protection from wind. Mulch lightly to retain moisture.

3

Vegetative/Vine Growth

6-10 weeks

Vigorous vine development with heart-shaped leaves. Purple foliage is most striking during this phase. Plants spread rapidly, covering ground and developing extensive root systems.

Support vines on trellises if space is limited, or allow to sprawl as a groundcover. Provide consistent moisture and occasional light feeding with balanced fertilizer. Remove any weeds competing for nutrients.

4

Flowering & Tuber Bulking

4-8 weeks

Small pink or purple flowers may appear, though Hawaiian Purple is often non-flowering. Simultaneously, underground tuber development accelerates. Vines continue spreading but growth slows as energy shifts to tuber enlargement.

Reduce nitrogen fertilizer to encourage tuber development rather than excess foliage. Maintain consistent watering. Avoid disturbing soil around plants. Continue monitoring for pests.

5

Harvest Ready

1-2 weeks pre-harvest

Tubers reach full size (3-12 inches long depending on variety and conditions). Purple skin and flesh are fully developed. Vines may begin to decline slightly.

After 100+ days, tubers should be harvestable. Stop watering 2-3 weeks before harvest to reduce moisture content and improve storage quality. Monitor soil temperature; harvest before it drops below 55°F.

Companion Planting

Plan your garden →

Plant with:

Basil Marigold Nasturtium Borage Pole beans

Avoid planting near:

Brassicas (cabbage, broccoli) Fennel Potatoes Tomatoes

Common Pests

  • Use reflective mulches, insecticidal soap, neem oil spray, or introduce natural predators like ladybugs

  • Use resistant varieties, practice crop rotation, remove infested tubers immediately, use insecticidal dust at planting

  • and

    Hand-pick larvae, use row covers on young plants, apply Bacillus thuringiensis (Bt), maintain good garden hygiene

  • Use nematode-resistant varieties, plant marigolds as companion plants, practice crop rotation, solarize soil if severe

  • Improve soil drainage, avoid overhead watering, remove infected plants, use disease-free seed stock, practice crop rotation

Uses

🍳

Nutritious Root Vegetable

Culinary

Hawaiian Purple sweet potatoes are excellent roasted, baked, or steamed as a side dish or in salads. The purple flesh adds visual appeal and can be used to make unique purees, fries, or chips. [source]

💊

Antioxidant & Anti-inflammatory Properties

Medicinal

High in anthocyanins and other polyphenols, Hawaiian Purple sweet potatoes possess strong antioxidant and anti-inflammatory properties that may support cardiovascular and immune health. [source]

🍳

Traditional Hawaiian Cuisine

Culinary

A staple in Hawaiian culture, 'ala ala is traditionally prepared in lu'au dishes, steamed, or mashed. It's central to Hawaiian food heritage and island agriculture. [source]

🏠

Ornamental Groundcover

Household

Beyond food production, Hawaiian Purple's vibrant purple foliage makes it an attractive ornamental plant for tropical and subtropical gardens, serving dual purposes as both food and landscape feature. [source]

🍳

Beverage & Dessert Applications

Culinary

The natural purple pigment and sweet flavor make Hawaiian Purple ideal for smoothies, desserts, baked goods, and beverages, offering both nutrition and striking color without artificial additives. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Harvest 100-150 days after planting slips, typically in fall before first frost. Dig carefully around plants to avoid damaging tubers. For best flavor and storage, harvest after a light frost which increases sugar content. Handle tubers gently to prevent bruising. Cure harvested tubers in warm (75-80°F), humid environment for 7-10 days before storage. Store in cool (55-60°F), dark location with good air circulation.

Fun Facts

  • 🌱 Hawaiian Purple sweet potatoes are not actually potatoes—they belong to the morning glory family (Convolvulaceae) and are completely unrelated to Irish potatoes, which are nightshades.
  • 🌱 The deep purple color comes from anthocyanins, the same antioxidants found in blueberries, but Hawaiian Purple contains them in much higher concentrations than orange sweet potatoes.
  • 🌱 Sweet potatoes were cultivated in Hawaii for centuries before European contact and remain deeply important to Hawaiian culture; the plant thrives in the islands' volcanic soil and warm climate.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Cultivar Full Sun Mulch pH Transplant Trellis
Shop Hawaiian Purple Sweet Potato plants and related plants at Plant Addicts →

Join 30,000 gardeners planning their gardens with LizPlants.

Get your personalized Hawaiian Purple Sweet Potato planting timeline

Tell us your zip code and we'll calculate exactly when to start Hawaiian Purple Sweet Potato seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.

Get my Hawaiian Purple Sweet Potato timeline →