Wormwood (Artemisia 'Powis Castle')
Artemisia 'Powis Castle' Wormwood offers aromatic, silvery, fern-like foliage perfect for dry, sunny rock gardens. Zones 6-9.
Complete Plant Information
Overview
Artemisia ‘Powis Castle’ is celebrated in the garden primarily for its outstanding foliage texture and color rather than its blooms. This horticultural highlight produces aromatic, finely-divided, silvery leaves that create a stunning contrast against greener garden companions. As a robust herbaceous perennial, this Wormwood variety offers evergreen structure in milder zones.
The cultivar ‘Powis Castle’ is renowned for its vigorous, bushy habit, typically forming a mound 2 to 3 feet high and wide, though it can spread further without restraint. It thrives in conditions that mimic its native dry temperate origins. Gardeners value Artemisia ‘Powis Castle’ for its reliability in hot, dry spots where many other perennials struggle to survive.
Introduced from Wales, this hybrid has earned high praise for its ornamental value, making it a staple for textural contrast. Planting Artemisia ‘Powis Castle’ ensures you have year-round interest provided the winter is not excessively harsh or wet.
Fast Facts
- Plant Family: Asteraceae
- Plant Type: Herbaceous perennial
- Hardiness Zones: USDA Zones 6-9
- Size at Maturity:
- Height: 2-3 ft
- Spread: 1-2 ft
- Bloom Time: August to October
- Bloom Description: Yellow
- Sun Exposure: Full sun
- Water Needs: Dry to medium
- Maintenance Level: Medium
How to Grow
The key to success with Wormwood, especially Artemisia ‘Powis Castle’, is diligent site selection focused on drainage. Plant during the spring after the last frost has passed, ensuring the site provides full sun exposure for the best foliage color and scent. It performs best in poor to moderately fertile soils, provided they are well-drained, handling dry to slightly medium moisture levels readily.
Excellent soil drainage is absolutely essential for growing this plant well; it does poorly, often succumbing swiftly, in moist or wet soils where root rot is a serious threat. Avoid amending heavy clay soils with too much organic matter if it risks holding excess water around the crown.
Water sparingly once established, allowing the soil to dry out between irrigations, matching its drought tolerance. Fertilization is rarely necessary, as rich soil can sometimes encourage floppier growth. In hot and humid southern climates, general foliage decline, especially in mid-summer, can occur.
Pruning is generally required to maintain a tight mound shape, as plants tend to open up in summer, exposing the woody base. Cut back by about one-third in early spring to encourage fresh, firm growth, or trim lightly after flowering if necessary.
Landscape Uses
The feathery, silvery foliage of Artemisia ‘Powis Castle’ makes it an excellent component in textural plantings across various garden styles. It functions perfectly as a ground cover plant, softening the hard lines of paving or rock structures.
Consider using it along retaining walls or at the fronts of borders where its low, spreading nature can effectively cloak bare soil or hide the feet of taller, coarser plants. It is also famously effective planted between stepping stones, provided foot traffic is minimal, allowing its rhizomatous spread to fill in gaps naturally. Artemisia ‘Powis Castle’ pairs wonderfully with dark-leaved or brightly colored annuals and perennials that benefit from its cool, silvery contrast.
Standout Features
Flower Qualities
- Insignificant
- Good Dried
Noteworthy Characteristics
The genus Artemisia includes about 200 species of aromatic shrubs and perennials, many featuring silvery, finely dissected foliage. ‘Powis Castle’ is specifically valued as a bushy, woody-based perennial grown for its aromatic, fern-like leaves that form a silvery mound. This highly-regarded cultivar was introduced from Powis Castle in Wales and remains a popular choice for textural interest.
Tolerances
- Rabbit
- Deer
- Drought
- Dry Soil
Potential Problems
The most common aesthetic concern with Artemisia ‘Powis Castle’ is that the plant tends to open up or become leggy during the summer heat, losing its pleasing mound shape. To mitigate this, aggressive pruning in early spring encourages denser basal growth.
Be aware of its rhizomatous spread, which, if unchecked, can lead to the plant colonizing more space than intended, especially in optimal growing conditions. Be watchful for signs of root rot if winter drainage is poor, as this is the primary failure mode for plants grown in wet soil.
Frequently Asked Questions
What hardiness zones is Wormwood suitable for?
Artemisia ‘Powis Castle’ is reliably hardy in USDA Zones 6 through 9.
How large does Artemisia ‘Powis Castle’ grow?
This perennial typically reaches a height between 2 and 3 feet, with a spread ranging from 1 to 2 feet, though it can widen if left unrestrained.
What sun exposure does Wormwood need?
Artemisia ‘Powis Castle’ requires full sun to maintain its best color and compact habit.
When does the foliage plant bloom?
While primarily grown for foliage, the insignificant yellow blooms appear from August through October.
Conclusion
For gardeners seeking reliable silver foliage and excellent drought tolerance, Artemisia ‘Powis Castle’ is an indispensable choice. Its aromatic texture provides stunning contrast throughout the growing season, successfully thriving where many other perennials fail. Before planting this robust Wormwood, confirm your location falls within USDA Zones 6-9 and ensure you can provide the full sun and sharp drainage it demands.
Companion Planting
When selecting companions for Artemisia ‘Powis Castle’, focus on plants that offer contrasting color and appreciate similar xeriscape conditions. Dark purple or deep burgundy foliage, such as that found on certain Penstemons or dark leaf Dahlias, pops dramatically against the silvery haze of the Wormwood.
Plants needing sharp drainage and full sun, like Sedums (Stonecrop) or certain low-growing Lavenders, make natural partners. Avoid planting Artemisia near moisture-loving perennials like Hosta or Ligularia, as the resulting cultural clash in watering needs will lead to stress for one or both species.
Seasonal Care Calendar
Early Spring: This is the ideal time for major rejuvenation. Cut back the previous season’s dead or tired growth by about one-third to maintain a tight, bushy habit for the coming year. Check soil moisture after winter snowmelt.
Summer: Monitor established plants for signs of opening up. Water only sparingly during prolonged dry spells; resist the urge to overwater, as this stresses the plant unnecessarily and promotes disease.
Fall: As blooms fade in late summer (August to October), you can trim off the spent flower stalks if the yellow color is undesirable, though the dried material can be harvested for use as Good Dried material. Generally, little fall cleanup is required.
Winter: In Zone 6, ensure the location does not become soggy during winter thaw cycles. For evergreen appearance in Zone 9, minimal intervention is needed, allowing the foliage to persist until new growth emerges.
