Garden PlannerEvidence-aware. Garden with confidence.
Entire healthy mature potato plant in a real garden bed, showing growth habit and scale.Primary identification image. 45–75 cm tall, 45–60 cm wide at maturity.

Potato

Solanum tuberosum L.

Also called: Irish potato, White potato

Family
Solanaceae
Season
Cool-season perennial tuber grown as an annual
Best grown in
Portland, Oregon

Grown from certified seed tubers planted in cool spring soil, hilled as they grow, and harvested after the tops die back.

Safety: Green tubers, sprouts, leaves and fruit contain solanine; discard green tubers.

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Life cycle & growth stages

  1. 1. Seed tuberChit seed potatoes in light for 2 weeks before planting.
  2. 2. EmergenceShoots appear 2–4 weeks after planting.
  3. 3. HillingEarth up stems when 20 cm tall; repeat.
  4. 4. FloweringTubers begin to bulk as plants flower.
  5. 5. Developing tubersKeep soil moist; tubers swell underground.
  6. 6. Harvest readyTops yellow and collapse.
  7. 7. HarvestLift carefully with a fork on a dry day; cure before storing.

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

Planting calendar for Portland, Oregon

direct sow 3 weeks before to 2 weeks after last frost; 70–120 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.

PotatoSolanum tuberosum
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
Potato—Mar 15–Apr 19 (estimate)——Apr 19–May 24 (estimate)May 24–Sep 14 (estimate)
  • Direct sow: Mar 15 – Apr 19
  • Tend and monitor: Apr 19 – May 24
  • Harvest: May 24 – Sep 14

Spacing & support

In-row 30–35 cm; rows 75–90 cm. Planner footprint: 1 cell of 30 cm.

Side-profile diagram of mature potato: canopy 45–75 cm tall, 45–60 cm wide, medium root zone, support and harvest-access envelope.

Soil & water

Soil
Loose, well-drained, slightly acid soil
pH
5–6.5
Fertility
moderate
Water
Steady moisture from flowering until harvest; avoid waterlogging.
Frost
half hardy; killed by frost

Support & training

Hill soil or mulch around stems. Install at planting so roots are not disturbed later.

Potato trained on its support: hill soil or mulch around stems.

Harvest signs

  • New potatoes: 2–3 weeks after flowering
  • Maincrop: tops yellow and die back
  • Skins set and do not rub off
Potato at harvest readiness, showing the visual cues: new potatoes: 2–3 weeks after flowering; maincrop: tops yellow and die back.

Common problems

Pests: Colorado potato beetle, wireworm, aphids (virus vectors), slugs

Diseases: late blight, early blight, common scab, blackleg

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

Side-by-side: healthy potato leaf or fruit and an example of late blight.

Container growing

  • Minimum 40 L (45 cm deep)
  • Use quality potting mix and water more frequently
  • Grow 2–3 seed potatoes per 40 L bag or bin and earth up as they grow.
Mature potato in a correctly sized container (40 L or more) with drainage visible.

Companion overview

7 reviewed relationship records (evidence: medium).

Supported or conditional

None reviewed

Avoid or separate

Eggplant, Strawberry, Tomato

Traditional claims only: Bush beans, Cucumber, Sunflower.

1 popular pairing reviewed with no verified relationship.

Full companion profile

Crop rotation

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

Year 1Year 2Year 3SolanaceaeOther familyOther familyback after 3+ years

Shared risks in Solanaceae: late blight (Phytophthora infestans), early blight, Verticillium and Fusarium wilts.

Crop 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 potato

Potatoes are planted as seed tubers 2–4 weeks before the last frost, once soil reaches about 7 °C (45 °F). Certified disease-free seed potatoes matter because the crop carries viruses and blight from one generation to the next. Chitting (pre-sprouting) in light for two weeks gives a faster start.

Potato planting material (crown, set, clove, slip or tuber) beside a ruler or coin for scale.
Potato seedling at cotyledon and first-true-leaf stage, in soil, distinguishable from common weeds.
Immature tuber of potato developing on the plant.

As stems grow, earth up soil or mulch around them; new tubers form on buried stems and turn green and bitter if exposed to light. Potatoes need moderate, steady water, especially while tubers are bulking after flowering.

Two or more mature potato plants with a tape measure showing in-row spacing (30–35 cm).
Potato flower detail or bolting stage.
Immature tuber of potato developing on the plant.

Late blight (Phytophthora infestans) attacks both potato and tomato; in wet summers, keep the two crops apart and remove infected foliage promptly. Colorado potato beetle is the main insect pest where it occurs. Rotate potatoes with other nightshades on a three-year cycle to limit blight, scab and wilt carryover.

Edible parts and safety

Edible: tuber. Green tubers, sprouts, leaves and fruit contain solanine; discard green tubers.

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

Pests and diseases

Common pests: Colorado potato beetle, wireworm, aphids (virus vectors), slugs. Common diseases: late blight, early blight, common scab, blackleg. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

Colorado potato beetle on potato, with a wider damage-context view.

Timeline

Season timeline for potato: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Direct sow Mar 15–Apr 19; Tend and monitor Apr 19–May 24; Harvest May 24–Sep 14.

Related plants

See also: Solanaceae 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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