Silver spurflower (Plectranthus argentatus)
Plectranthus argentatus, the Silver spurflower, offers striking fuzzy, gray-green foliage. A medium-maintenance perennial for Zones 10-11.
Complete Plant Information
Overview
Plectranthus argentatus, widely recognized as Silver spurflower, is cherished primarily for its highly ornamental, fuzzy, gray-green foliage rather than its summer blooms. This upright-spreading sub-shrub brings significant contrast and texture to shaded garden areas with its distinctive silvery pubescence covering ovate, scallop-edged leaves. Gardeners appreciate this Australian native for its tolerance to heat, humidity, and surprisingly, some soil dryness once established.
When grown as a perennial in its ideal climates (USDA Zones 10-11), Plectranthus argentatus provides reliable structure throughout the growing season. In cooler regions, it performs admirably as a foliage annual, offering a vibrant vertical accent in containers or mixed borders. The genus name references the spur-shaped flowers, though the main attraction remains the silvery leaves of the Plectranthus argentatus.
The Silver spurflower matures into a manageable size, typically reaching 2 to 3 feet both in height and spread. It offers year-round visual interest when overwintered indoors, making it a versatile choice for both landscaping and container cultivation.
Fast Facts
- Plant Family: Lamiaceae
- Plant Type: Herbaceous perennial
- Native Range: Australia
- Hardiness Zones: USDA Zones 10-11
- Size at Maturity:
- Height: 2-3 ft
- Spread: 2-3 ft
- Bloom Time: July to August
- Bloom Description: Bluish-white
- Sun Exposure: Part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
For optimal growth of Plectranthus argentatus, plant in rich, humusy, well-drained soil. While it prefers medium moisture, ensure the soil is not poorly drained, particularly avoiding heavy clay soils, which can lead to root rot. The best location usually grants part shade or dappled sunlight; however, in cooler summer climates, the Silver spurflower can handle periods of full sun.
Watering should be consistent and even, especially when grown as an annual or in containers, although the plant exhibits tolerance to temporary dryness once mature. Fertilization is generally not strenuous, aligning with its medium maintenance rating. If grown for the best foliage display, gardeners can proactively pinch back emerging flower buds as they appear to direct energy back into leaf production.
As plants intolerant of frost, ensure you bring containerized Plectranthus argentatus indoors before the first hard freeze, placing them in cool, bright locations to overwinter as houseplants. This species is exceptionally easy to propagate; simply take cuttings to ensure a continuous supply of this attractive silvery foliage.
Landscape Uses
The primary appeal of the Silver spurflower lies in its texture and color, making it a fantastic textural contrast plant in borders and foundation plantings. Use it as a mid-layer specimen where its fuzzy, silvery leaves can offset the deep greens of shade-loving perennials or anchor bolder, colorful annuals.
When planted in containers, Plectranthus argentatus makes an excellent “thriller” or “filler” due to its upright habit and consistent color. It pairs well with deep purple or dark green foliage plants, which dramatically highlight the leaf’s pale, silvery sheen. In St. Louis or similar climates, growing it as a summer annual allows for rotational patio displays in large pots.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Plectranthus argentatus, commonly called silver spurflower, is an upright-spreading, woody-based sub-shrub that is native to Australia. Although its flowers are somewhat showy, this plant is usually grown primarily for its attractive, fuzzy, gray-green foliage. Ovate, scallop-edged, pointed, gray-green leaves are covered with a silvery pubescence, creating a significant textural element in the garden.
Tolerances
- Dry Soil
Potential Problems
Gardeners should remain vigilant for common houseplant and subtropical pests, including mealybugs, scale insects, and mites, particularly when growing Plectranthus argentatus indoors or in humid conditions. These sucking insects can weaken the plant rapidly if not controlled through regular inspection and appropriate horticultural oils or insecticidal soaps.
In overly wet or poorly draining soil conditions, the Silver spurflower becomes susceptible to fungal issues such as root rot and leaf spot. Proper soil preparation, ensuring excellent drainage, is the best preventative measure against these moisture-related diseases.
Frequently Asked Questions
What hardiness zones is Silver spurflower suitable for?
The Plectranthus argentatus is winter hardy specifically in USDA Zones 10 through 11 in the ground.
How large does Silver spurflower grow?
This plant typically reaches a mature height between 2 and 3 feet tall, with a similar spread of 2 to 3 feet wide.
When does Silver spurflower bloom?
The plant produces its tubular, bluish-white flowers primarily during the summer months, specifically from July through August.
What sun exposure does Silver spurflower need?
The general recommendation for Plectranthus argentatus is part shade, though it tolerates full sun in cooler summer climates.
Conclusion
The Silver spurflower offers unparalleled silvery texture, making it an invaluable asset for brightening shaded corners or lending contrast to containers. This highly decorative Plectranthus argentatus merges medium maintenance with high aesthetic reward when sited correctly in warm environments. Before planting, confirm your local hardiness zone compatibility, or plan to treat it as a cherished foliage annual or houseplant.
Propagation Tips
Due to its woody-based structure, Plectranthus argentatus is easily and quickly multiplied using stem cuttings. Cuttings taken from semi-hardwood or soft new growth root readily in moist, well-drained potting mix or even directly in water under warm conditions. This ease of propagation allows gardeners to create numerous new plants for yearly rotation or for gifting friends who admire the fantastic fuzzy foliage.
Container Growing
Growing the Silver spurflower in pots is highly recommended, especially for gardeners outside of Zones 10-11 who wish to overwinter them indoors. Use a high-quality, light potting mix blended with extra perlite or grit to guarantee fantastic drainage, which is crucial for preventing root issues in containers. Ensure containers are large enough, as the plant will spread up to 3 feet wide, and move them to a bright, cool location indoors before temperatures drop near freezing.
