How to Grow Westringia 'Grasstrees Blue'
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Westringia 'Grasstrees Blue'
Westringia fruticosa 'Grasstrees Blue'
shrubWestringia 'Grasstrees Blue' is a compact, evergreen Australian shrub prized for its narrow, silvery-green foliage and delicate blue flowers. It's a drought-tolerant ornamental that thrives in Mediterranean and warm temperate climates, making it ideal for xeriscaping and coastal gardens. The plant maintains a neat, mounding habit and attracts native bees and pollinators throughout the growing season.
When should you plant Westringia 'Grasstrees Blue' in your zone?
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Example Westringia 'Grasstrees Blue' timeline · Pittsburgh, PA (Zone 6b)
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Plant Westringia 'Grasstrees Blue'
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Westringia 'Grasstrees Blue'
Late summer into fallBefore the first fall frost (≈ Nov 8)
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 9b-11; can survive in zone 9a with winter protection
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Establishment
3-6 monthsYoung transplant developing root system; compact foliage mounding slowly
Water regularly but allow soil to dry between waterings. Protect from extreme heat and wind first season. No fertilizer needed; avoid heavy watering.
Vegetative Growth
6-18 monthsFoliage densifies and branches elongate; plant reaches 60-80% mature size
Light pruning to shape; encourage branching by removing branch tips. Reduce watering frequency as establishment progresses. No fertilizer needed.
Flowering
4-8 months (spring through early autumn)Small, delicate blue flowers (sometimes white tinged) appear along branch tips; flowers attract pollinators
Flowers appear spring through summer and may continue into autumn. Deadheading encourages continued blooming but is optional. Maintain dry conditions to prevent fungal issues.
Mature Shrub
Year 2 onward (indefinite)Reaches 2-3 feet tall and wide; dense silvery-green foliage with consistent flowering; well-established drought tolerance
Minimal maintenance required. Prune lightly after flowering to maintain shape. No watering except during extended drought. No fertilizer needed.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Rare but can occur in extreme heat and drought stress. Increase air circulation; hose off foliage; apply neem oil if severe.
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Prune affected branches; apply horticultural oil in late winter; improve air circulation.
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Usually indicates overwatering or poor air circulation. Improve drainage and air flow; avoid overhead watering. Spray with sulfur if necessary.
Uses
Xeriscaping & drought-resistant landscaping
OrnamentalWestringia 'Grasstrees Blue' is an excellent choice for water-wise gardens, coastal landscapes, and regions with water restrictions. Its silvery foliage and blue flowers provide color and texture while requiring minimal irrigation once established. [source]
Pollinator attraction
WildlifeThe delicate blue flowers attract native bees, butterflies, and other pollinators throughout the growing season. In Australian gardens, it supports native bee populations and contributes to garden biodiversity. [source]
Floral arrangements & cut flowers
HouseholdStems with blue flowers make attractive additions to floral arrangements and can be enjoyed indoors. The silvery foliage provides excellent filler material for bouquets. [source]
Coastal and salt-tolerant gardening
OrnamentalWestringia naturally tolerates salt spray and coastal conditions, making it ideal for seaside gardens where many ornamentals struggle. It thrives in exposed, windy coastal locations. [source]
Harvest Tips
Westringia is ornamental; cut stems for floral arrangements during flowering season (spring-early summer). Harvest 6-8 inches of tip growth for arrangements; this also benefits the plant by encouraging branching.
Fun Facts
- 🌱 Westringia fruticosa is native to southeastern Australia and is sometimes called 'Australian rosemary' due to its superficially similar needle-like foliage, though it is not related to true rosemary.
- 🌱 'Grasstrees Blue' is a cultivar developed specifically for its compact habit and vibrant blue flowers, making it more ornamentally superior to the species form.
- 🌱 This shrub is highly efficient in Mediterranean and drought conditions due to its narrow leaves, which reduce water loss through transpiration—an adaptation to dry climates.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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