Garden PlannerEvidence-aware. Garden with confidence.
Entire healthy mature sweet potato plant in a real garden bed, showing growth habit and scale.Primary identification image. 30–30 cm tall, 120–250 cm wide at maturity.

Sweet potato

Ipomoea batatas (L.) Lam.

Family
Convolvulaceae
Season
Warm-season tender perennial grown as an annual
Best grown in
Portland, Oregon

A sprawling, heat-loving vine grown from slips; needs 90–120 warm days and loose soil for its roots.

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Life cycle & growth stages

  1. 1. SlipPlant rooted slips deeply in warm soil.
  2. 2. EstablishmentSlips wilt then recover within a week.
  3. 3. ViningVines cover the bed by midsummer.
  4. 4. Developing rootsTubers swell from late summer.
  5. 5. Harvest readyFoliage yellows; before frost.
  6. 6. Harvest and cureDig gently; cure warm and humid.

Growth stages are ordered chronologically; timing varies with cultivar, temperature, light and care.

Planting calendar for Portland, Oregon

transplant 3–6 weeks after last frost; 90–120 days to maturity from planting. Windows are derived from the region's average frost dates (last Apr 5, first Nov 5) and are estimates until you confirm your own dates in the calendar.

Sweet potatoIpomoea batatas
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
Sweet potato———Apr 26–May 17 (estimate)May 17–Jul 25 (estimate)Jul 25–Sep 28 (estimate)
  • Transplant outdoors: Apr 26 – May 17
  • Tend and monitor: May 17 – Jul 25
  • Harvest: Jul 25 – Sep 28

Spacing & support

In-row 30–45 cm; rows 90–120 cm. Planner footprint: 4 cells of 30 cm.

Side-profile diagram of mature sweet potato: canopy 30–30 cm tall, 120–250 cm wide, medium root zone, support and harvest-access envelope.

Soil & water

Soil
Loose, sandy, well-drained soil
pH
5.5–6.5
Fertility
low
Water
Regular water early; drought-tolerant later; stop 2–3 weeks before harvest.
Frost
tender; killed by frost

Support & training

No support structure needed.

Sweet potato mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Harvest signs

  • Leaves begin to yellow in autumn
  • Before the first frost
  • Cure 7–10 days warm and humid
Sweet potato at harvest readiness, showing the visual cues: leaves begin to yellow in autumn; before the first frost.

Common problems

Pests: wireworm, deer, sweet potato weevil (warm regions)

Diseases: scurf, Fusarium wilt

Appearance alone is not a diagnosis; confirm with a regional extension guide.

Side-by-side: healthy sweet potato leaf or fruit and an example of scurf.

Container growing

  • Minimum 40 L (35 cm deep)
  • Use quality potting mix and water more frequently
  • Bush cultivars in 40 L grow bags.
Mature sweet potato in a correctly sized container (40 L or more) with drainage visible.

Companion overview

1 reviewed relationship record (evidence: low).

Supported or conditional

None reviewed

Avoid or separate

None with evidence

1 popular pairing reviewed with no verified relationship.

Full companion profile

Crop rotation

Avoid planting sweet potato or other other crops in the same spot for 3 years. Rotation is about previous seasons, not about live neighbours.

Year 1Year 2Year 3ConvolvulaceaeOther familyOther familyback after 3+ yearsCrop rotation hub

Sources, reviewer & update

Sources

Reviewer: Garden Planner editorial team (pending independent horticultural review)

Last reviewed: August 15, 2026 · version 1

Found an error or have feedback? Let us know.

Growing sweet potato

Sweet potatoes are planted as rooted slips 3–6 weeks after the last frost into warm soil, ideally under black mulch in cooler regions. Vines sprawl 1–2.5 m and suppress weeds; roots form along the original stem, so do not let vines root down along their length if you want large tubers.

Sweet potato planting material (crown, set, clove, slip or tuber) beside a ruler or coin for scale.
Sweet potato seedling at cotyledon and first-true-leaf stage, in soil, distinguishable from common weeds.
Sweet potato mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Harvest before frost, handle gently, and cure at 27–30 °C with high humidity for a week to sweeten and heal the skin. Sweet potato is not related to potato and is in its own family for rotation.

Two or more mature sweet potato plants with a tape measure showing in-row spacing (30–45 cm).
Sweet potato flower detail or bolting stage.
Immature tuberous root of sweet potato developing on the plant.

Edible parts and safety

Edible: tuberous root, leaves.

Hands or tool harvesting sweet potato correctly (cut, pull, twist or pick) without damaging the plant.

Pests and diseases

Common pests: wireworm, deer, sweet potato weevil (warm regions). Common diseases: scurf, Fusarium wilt. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

wireworm on sweet potato, with a wider damage-context view.

Timeline

Season timeline for sweet potato: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Transplant outdoors Apr 26–May 17; Tend and monitor May 17–Jul 25; Harvest Jul 25–Sep 28.

Related plants

See also: Convolvulaceae family page · crop rotation · regional calendar · guides

Our Methodology & Sources

We synthesize peer-reviewed research, university extension publications, and trusted horticulture resources. Our evidence levels help you understand how strong the science is behind the guidance.

Evidence tiers

Supported evidenceConsistent results from multiple robust studies
Traditional claimHistorical use reported, limited scientific support
Context dependentMixed or variable results across conditions
No verified relationshipNo reliable evidence identified

Primary source types

  • Peer-reviewed journal articles
  • University extension publications
  • Government & research institute reports
  • Systematic reviews & meta-analyses

Last updated

August 24, 2026

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