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Entire healthy mature spinach plant in a real garden bed, showing growth habit and scale.Primary identification image. 15–25 cm tall, 15–20 cm wide at maturity.

Spinach

Spinacia oleracea L.

Family
Amaranthaceae
Season
Cool-season annual
Best grown in
Portland, Oregon

A very hardy leaf crop for early spring and autumn; long days and heat make it bolt within weeks.

Safety: High in oxalates; fine in normal amounts.

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Life cycle & growth stages

  1. 1. SeedSow 1.5 cm deep in cool soil.
  2. 2. SeedlingEmerges in 5–10 days.
  3. 3. ThinningThin to 8–10 cm.
  4. 4. Mid-growthRosette fills out in 3–4 weeks.
  5. 5. Harvest readyLeaves 8–15 cm.
  6. 6. HarvestPick outer leaves or cut whole plant.
  7. 7. BoltingCentral stem rises with long days and heat.

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

Planting calendar for Portland, Oregon

direct sow 0–6 weeks before last frost; 35–50 days to maturity from sowing. 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.

SpinachSpinacia oleracea
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
Spinach—Feb 22–Apr 5 (estimate); Apr 5–Sep 17 (estimate)Sep 10–Oct 8 (estimate)——Mar 29–Nov 27 (estimate)
  • Direct sow: Feb 22 – Apr 5
  • Harvest: Mar 29 – Nov 27
  • Succession sow: Apr 5 – Sep 17
  • Autumn sowing: Sep 10 – Oct 8

Spacing & support

In-row 8–10 cm; rows 30–30 cm. Planner footprint: 1 cell of 30 cm, 9 plants per cell.

Side-profile diagram of mature spinach: canopy 15–25 cm tall, 15–20 cm wide, shallow root zone, support and harvest-access envelope.

Soil & water

Soil
Fertile, moisture-retentive loam
pH
6.5–7.5
Fertility
high
Water
Constant moisture delays bolting.
Frost
very hardy; tolerates frost

Support & training

No support structure needed.

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

Harvest signs

  • Leaves 8–15 cm long
  • Before the central stem begins to rise
Spinach at harvest readiness, showing the visual cues: leaves 8–15 cm long; before the central stem begins to rise.

Common problems

Pests: leaf miner, aphids, slugs

Diseases: downy mildew

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

Side-by-side: healthy spinach leaf or fruit and an example of downy mildew.

Container growing

  • Minimum 5 L (15 cm deep)
  • Use quality potting mix and water more frequently
Mature spinach in a correctly sized container (5 L or more) with drainage visible.

Companion overview

3 reviewed relationship records (evidence: low).

Supported or conditional

None reviewed

Avoid or separate

None with evidence

Traditional claims only: Peas, Strawberry.

1 popular pairing reviewed with no verified relationship.

Full companion profile

Crop rotation

Avoid planting spinach or other beet family crops in the same spot for 2 years. Rotation is about previous seasons, not about live neighbours.

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

Shared risks in Amaranthaceae: leaf miner (Pegomya), Cercospora leaf spot, downy mildew.

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 spinach

Spinach is sown directly as soon as the soil can be worked and again from late summer; autumn-sown plants often overwinter under cover for the earliest spring harvest. Germination fails above about 24 °C, so summer sowings rarely succeed.

Spinach seed beside a ruler or coin for scale.
Spinach seedling at cotyledon and first-true-leaf stage, in soil, distinguishable from common weeds.
Spinach mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Plants are small and shallow-rooted, so they fit between slower crops and in containers. Pick outer leaves or cut whole plants 2 cm above the crown for regrowth.

Two or more mature spinach plants with a tape measure showing in-row spacing (8–10 cm).
Spinach flower detail or bolting stage.
Immature leaves of spinach developing on the plant.

Leaf miners, shared with beet and chard, tunnel the leaves; mesh cover prevents egg-laying. Downy mildew favours cool, damp, crowded conditions, so space plants and choose resistant cultivars.

Edible parts and safety

Edible: leaves. High in oxalates; fine in normal amounts.

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

Pests and diseases

Common pests: leaf miner, aphids, slugs. Common diseases: downy mildew. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

leaf miner on spinach, with a wider damage-context view.

Timeline

Season timeline for spinach: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Direct sow Feb 22–Apr 5; Harvest Mar 29–Nov 27; Succession sow Apr 5–Sep 17; Autumn sowing Sep 10–Oct 8.

Related plants

See also: Amaranthaceae 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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