Giant scabious

Sun

Full sun or light partial shade; flowering and stem strength are best in sun.

Water

Moderate; keep newly planted clumps evenly moist. Water established plants during prolonged dry spells, especially while flower stems are developing.

Soil

Deep, fertile, moisture-retentive but well-drained soil; tolerates clay if it does not remain waterlogged.

Height

6-8 ft (1.8-2.4 m)

Spread

3-4 ft (0.9-1.2 m)

Flowers

Early to late summer; soft sulphur-yellow pincushion flowers.

Foliage

Large, deeply divided green leaves form a basal mound, with smaller leaves along the tall stems; dies back in winter.

Growth

Moderate to fast; allow two or three growing seasons for a substantial clump.

Care needed

Low

• Pollinators
• Cold hardy
• Wildlife
• Low allergen

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 ft (0.3 m)

2. After 1 year

   3 ft (1.1 m)

3. After 2 years

   6 ft (1.8 m)

4. After 3 years

   7 ft (2.1 m)

   full size

About 2 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

Safe

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Water deeply during the first growing season and during extended summer drought.
• Apply compost around the clump in spring; avoid heavy nitrogen feeding, which encourages floppy growth.
• Mulch to conserve moisture, keeping mulch away from the crown.
• Install discreet supports in spring if the site is windy or partly shaded.
• Remove unwanted seedlings while small; divide crowded clumps in spring if flowering declines.

Pruning. Remove spent flower stems to limit self-seeding, or leave some seedheads for autumn structure. Cut dead stems to near ground level in late winter or early spring before new growth develops.

Early spring

Cut down remaining dead stems and remove weeds around emerging shoots.

Spring

Plant or divide clumps, water thoroughly and top-dress with compost.

Late spring

Set supports around developing stems in exposed positions.

Summer

Water during prolonged dry weather and remove spent flowers if seedlings are unwanted.

Autumn

Collect ripe seed, or leave selected seedheads standing for seasonal structure.

Winter

Check that water is not pooling around the dormant crown.

• Place at the back of a deep mixed border, where its pale flowers rise above shorter perennials.
• Repeat through naturalistic planting with ornamental grasses for height without a solid visual screen.
• Combine with blue or violet flowers, such as catmint and meadow sage, for a soft colour contrast.
• Use in a large cottage or wildlife border where its broad basal clump has room to develop.

Garden styles it suits: English country, Cottage garden, New perennial (prairie), Wildlife garden, Pollinator garden and Pastel border.

Plant it with: Catmint, Meadow sage, Hardy geranium, Culver's root, Feather reed grass and Purple coneflower.

Wildlife: The open flowers provide nectar and pollen for bees, butterflies and other visiting insects. Standing stems offer shelter for small invertebrates over winter.

• Slugs and snails may damage emerging shoots; check young growth and use barriers, hand-picking or labelled iron-phosphate bait where needed.
• Stems can flop in shade, rich soil or strong wind; provide more sun, avoid excess fertiliser and support stems early.
• Waterlogged soil can cause crown or root rot; improve drainage or move the plant to a better-drained position.
• Self-sown seedlings can become numerous; remove flowerheads before seed ripens and pull unwanted seedlings promptly.

Not known to be toxic to people, cats, dogs or horses. Species-specific safety information is limited; it is an ornamental plant, not a food plant.

• Field scabious (Knautia arvensis)

  Usually much shorter, with lilac or pinkish-purple pincushion flowers rather than pale yellow flowers.

• Common teasel (Dipsacus fullonum)

  Has prickly stems and elongated, spiny flowerheads with bands of lilac flowers; giant scabious has rounded, soft-looking yellow flowerheads.

Cephalaria comes from the Greek word for head, referring to the flowerheads, while gigantea means giant and describes the plant's stature.

Propagation. Sow ripe seed in autumn in pots outdoors; germination can be slow and uneven, and winter cold may help. Divide established clumps in early spring, retaining several healthy shoots and a good portion of root on each division.

Accepted botanical name

Cephalaria gigantea

In the US and Canada

Introduced in Canada and the lower 48 states.

Native range

North Caucasus, Transcaucasus and Turkey.

Measured

Average height 100 cm.

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