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

Borage

Borago officinalis L.

Also called: Starflower

Family
Boraginaceae
Season
Warm-season annual
Best grown in
Portland, Oregon

A coarse, self-seeding annual whose blue flowers refill with nectar quickly and are a bumblebee favourite.

Safety: Leaves contain small amounts of pyrrolizidine alkaloids; eat only occasionally.

Note: Self-seeds freely; manage seedlings.

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Life cycle & growth stages

  1. 1. SeedSow 1 cm deep after frost.
  2. 2. SeedlingEmerges in 7–14 days.
  3. 3. Mid-growthCoarse, hairy leaves; fast growth.
  4. 4. FloweringBlue star flowers for weeks; bumblebees.
  5. 5. Self-seedingDrops seed; pull unwanted seedlings.

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

Planting calendar for Portland, Oregon

direct sow from last frost to 4 weeks after; 50–60 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.

BorageBorago officinalis
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
Borage—Apr 5–May 3 (estimate)——May 3–May 25 (estimate)May 25–Nov 5 (estimate)
  • Direct sow: Apr 5 – May 3
  • Tend and monitor: May 3 – May 25
  • Harvest: May 25 – Nov 5

Spacing & support

In-row 45–60 cm; rows 60–60 cm. Planner footprint: 2 cells of 30 cm.

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

Soil & water

Soil
Any soil
pH
6–7
Fertility
low
Water
Moderate; drought-tolerant once established.
Frost
tender; killed by frost

Support & training

No support structure needed.

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

Harvest signs

  • Pick flowers fully open
  • Young leaves before bristles harden
Borage at harvest readiness, showing the visual cues: pick flowers fully open; young leaves before bristles harden.

Common problems

Pests: aphids (occasionally)

Diseases: powdery mildew late season

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

Side-by-side: healthy borage leaf or fruit and an example of powdery mildew late season.

Container growing

  • Minimum 10 L (25 cm deep)
  • Use quality potting mix and water more frequently
Mature borage in a correctly sized container (10 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: Strawberry, Tomato, Zucchini.

Full companion profile

Crop rotation

Avoid planting borage or other other crops in the same spot for 1 year. Rotation is about previous seasons, not about live neighbours.

Year 1Year 2Year 3BoraginaceaeOther familyOther familyback after 1+ 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 borage

Borage is sown directly after the last frost and grows fast into a bristly 45–75 cm plant with star-shaped blue flowers from early summer. It self-seeds enthusiastically; pull unwanted seedlings early.

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

Borage flowers are visited constantly by bumblebees and honeybees, which makes it a useful pollinator plant near crops that need bees (squash, strawberries). Traditional claims that it deters tomato hornworm or improves strawberries have no controlled evidence. Its deep taproot and broad leaves make it a competitor at close spacing.

Two or more mature borage plants with a tape measure showing in-row spacing (45–60 cm).
Borage flower detail or bolting stage.
Immature flowers of borage developing on the plant.

Edible parts and safety

Edible: flowers, young leaves (sparingly). Leaves contain small amounts of pyrrolizidine alkaloids; eat only occasionally.

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

Pests and diseases

Common pests: aphids (occasionally). Common diseases: powdery mildew late season. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

aphids on borage, with a wider damage-context view.

Timeline

Season timeline for borage: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Direct sow Apr 5–May 3; Tend and monitor May 3–May 25; Harvest May 25–Nov 5.

Related plants

See also: Boraginaceae 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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