Wormwood 'Powis Castle'

Sun

Full sun; shade produces looser growth and less silvery foliage.

Water

Water regularly while establishing, then sparingly. Established plants tolerate drought but dislike persistently damp roots.

Soil

Well-drained sandy, gritty or gravelly soil of low to moderate fertility; tolerates a range of soil pH. Avoid wet clay unless drainage is substantially improved.

Height

2-3 ft (0.6-0.9 m)

Spread

3-5 ft (0.9-1.5 m)

Foliage

Evergreen. Finely cut, soft-looking silver-grey leaves with a strong herbal scent when brushed or crushed.

Growth

Fast in suitable conditions.

Care needed

Low

• Deer resistant
• Drought tolerant
• Heat tolerant
• Fragrant

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   1.9 ft (0.58 m)

3. After 2 years

   2.1 ft (0.65 m)

4. After 3 years

   2.4 ft (0.73 m)

5. After 5 years

   2.5 ft (0.75 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Growth rate

Fast

• Water deeply during the first growing season, allowing the soil to dry between waterings.
• Plant where winter rain drains away quickly; use a raised bed or a container with drainage holes if necessary.
• Avoid routine feeding and rich compost, which encourage floppy growth.
• Keep damp organic mulch away from the woody crown; a light gravel mulch is suitable.
• Allow room for its broad mound rather than crowding it against neighbouring plants.

Pruning. In spring, once strong new growth is visible and severe frosts have passed, shorten stems to build a compact mound, keeping leafy shoots below each cut. Avoid cutting into bare old wood or pruning hard in autumn.

Spring

Plant after severe frost risk has passed, choosing full sun and sharply drained soil.

Mid-spring

Prune established plants once new shoots show which stems are alive.

Early summer

Take softwood cuttings from healthy, non-flowering shoots.

Summer

Water young plants during dry spells; lightly trim wayward leafy shoots if needed.

Autumn

Clear fallen leaves from the crown and check that surrounding soil drains freely.

Winter

Avoid hard pruning and keep container plants out of standing water.

• Repeat rounded silver mounds through a sunny gravel garden with lavender and ornamental grasses.
• Use beside purple salvias or dark-leaved plants to make their colours stand out.
• Place near the front of a broad mixed border, allowing space for its spreading branches.
• Grow in a large, freely drained container as a foliage contrast to upright plants.
• Use along a sunny path where its aromatic leaves can be brushed without blocking the walkway.

Garden styles it suits: Mediterranean, Dry gravel garden, Cottage garden, Coastal, Desert / xeriscape and Moon garden.

Plant it with: Lavender, Russian sage, Catmint, Bearded iris, Yarrow and Blue fescue.

Wildlife: Primarily a foliage plant, with limited value for pollinators because flowering is uncommon. Its aromatic foliage is often avoided by deer and rabbits, though browsing is still possible.

• Root and crown rot in wet soil: improve drainage or move to a raised bed; replace plants whose crowns have rotted.
• Floppy, open growth: provide full sun, stop feeding and reduce unnecessary watering.
• Woody, bare centres with age: prune leafy growth annually and raise replacement plants from cuttings.
• Winter dieback: wait for spring growth before removing dead stems, and avoid autumn pruning.

Not a culinary wormwood. Cultivar-specific toxicity information is limited; treat the leaves, stems and their concentrated oils as potentially harmful if eaten by people, cats, dogs or horses. Ingestion may cause digestive upset, and concentrated oils can cause more serious poisoning; avoid using it in food or home remedies. Sap or foliage may irritate sensitive skin.

• Common wormwood (Artemisia absinthium)

  Usually more upright, with coarser, broader leaf divisions and more conspicuous sprays of small yellowish flower heads.

• Southernwood (Artemisia abrotanum)

  Has greener, threadlike foliage and a more upright, twiggy outline rather than a broad silver mound.

• Silver mound artemisia (Artemisia schmidtiana 'Nana')

  Forms a much smaller, low cushion of fine silver foliage and lacks the substantial woody framework of 'Powis Castle'.

The cultivar name refers to Powis Castle in Wales, where this garden selection was introduced.

Propagation. Take softwood cuttings in late spring or early summer, or semi-ripe cuttings later in summer, and root them in a gritty propagation mix. Cuttings preserve the cultivar; seed is not a reliable way to reproduce it.

Accepted botanical name

Artemisia

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.