How to Grow Rubinstern

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Rubinstern

Geum 'Rubinstern'

flower

Rubinstern is a compact perennial geranium (not a true geranium, but often called cranesbill) with deep ruby-red semi-double flowers that bloom prolifically from late spring through summer. This cultivar is prized for its vibrant color, long flowering period, and attractive finely-cut foliage that often takes on reddish tones. It reaches 12-18 inches tall and is excellent for borders, rock gardens, and containers.

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Example Rubinstern timeline · Pittsburgh, PA (Zone 6b)

Plant Rubinstern
Around Apr 17

Near Pittsburgh's average last spring frost.
Tend & protect
Late spring–summer

Watering, feeding, and pest-watch reminders.
First Rubinstern blooms
Mid-to-late summer

Before the first fall frost (≈ Nov 8)

Sample dates for Pittsburgh, PA. Sign up to get exact Rubinstern dates for your own zip code.

Growing Conditions

☀️

Sun: Full sun to partial shade; 6+ hours of direct sunlight daily for best blooming

💧

Water: Moderate; keep soil consistently moist but not waterlogged. Water deeply once or twice weekly depending on rainfall. Reduce watering in winter.

📏

Spacing: 12 inches

📅

Days to maturity: Blooms in the first season, matures fully by year 2

🌱

Planting depth: Plant crowns at soil level; do not bury

Soil

Type: Well-draining loamy soil

pH: 6.0-7.0

Amendments:

Compost Perlite for drainage Aged bark mulch

Growing Zones

Find your zone →

Thrives in USDA zones 3-8, with best performance in cooler regions

3a 3b 4a 4b 5a 5b 6a 6b 7a 7b 8a

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Growth Stages

Dormancy/Spring Emergence

4-6 weeks

Plant breaks dormancy with reddish basal foliage emerging from crowns

Divide or plant in early spring. Remove winter mulch once growth begins. Apply balanced fertilizer as growth starts.

Vegetative Growth

4-6 weeks

Compact mounding growth with deeply cut, serrated foliage; fine texture, reddish tinges visible

Maintain consistent moisture. Fertilize monthly with balanced feed. Deadhead spent flowers to encourage more blooms.

Flowering

8-12 weeks (late May through August)

Abundant deep ruby-red semi-double flowers on wiry stems above foliage; flowers appear in waves

Deadhead regularly for continuous blooming. Stake if necessary in windy locations. Continue watering and fertilizing.

Late Season

4-8 weeks

Flowering slows but continues sporadically. Foliage may look tired in hot climates; seeds develop on spent flowers

Reduce fertilizer. Cut back lightly if foliage becomes tatty. Collect seeds if desired. Prepare for dormancy.

Winter Dormancy

3-4 months

Plant dies back or remains semi-evergreen depending on zone and winter severity

Apply 2-3 inches of mulch in zones below 5. Do not cut back until spring. Ensure good drainage to prevent crown rot.

Companion Planting

Plan your garden →

Plant with:

Catmint (Nepeta) Coral bells (Heuchera) Sage (Salvia) Lavender Achillea Coreopsis Geraniums (hardy types) Alliums

Avoid planting near:

Plants requiring consistently wet soil Tall competitors that shade it excessively Aggressive spreaders like goutweed

Common Pests

Hand-pick affected leaves; spray with insecticidal soap or spinosad if severe; encourage beneficial insects
Increase humidity; spray with water; use neem oil or miticide if infestation is heavy
and
Hand-pick at dusk; create barriers with diatomaceous earth or copper tape; beer traps
Remove infected foliage; improve air circulation; avoid overhead watering; apply fungicide if severe

Uses

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Edible flowers

Culinary

The vibrant ruby-red flowers are edible and can be used as garnishes for salads and desserts, adding a delicate, slightly tangy flavor and striking visual appeal. [source]

💊

Traditional herbal remedy

Medicinal

Geum species have been used in traditional herbal medicine to support digestion and as an astringent, though modern clinical evidence is limited. [source]

🏠

Cut flower arrangements

Household

The long-lasting ruby-red semi-double flowers are excellent for cutting and vase arrangements, providing color and texture for several days. [source]

🦋

Pollinator support

Wildlife

Rubinstern attracts bees, butterflies, and other beneficial insects throughout its long flowering season, making it valuable for pollinator gardens. [source]

🎨

Dried flower arrangements

Craft

The flowers and foliage can be dried for use in dried arrangements, wreaths, and other craft projects while maintaining good color retention. [source]

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

Harvest Tips

Not a harvested plant; pinch off spent flowers regularly to extend the blooming period and improve appearance. If collecting seeds, allow some flowers to remain on plant and collect seedheads when brown and dry in late summer.

Fun Facts

🌱 Rubinstern is a cultivar of Geum coccineum, a Balkan alpine species, selected for superior color and longer bloom time than wild forms.
🌱 The name 'Rubinstern' translates to 'Ruby Star' in German, referring to the jewel-like appearance of its deep red flowers.
🌱 Unlike true geraniums (Pelargonium), which are tender annuals in most climates, hardy geraniums like Geum are perennials that return reliably year after year.

Gardening Terms

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

Crown Cultivar Deadhead Full Sun Mulch Partial Shade Perennial

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