Thryallis

Sun

Full sun gives the densest growth and most flowers; tolerates light partial shade.

Water

Water regularly while establishing. Once established, it tolerates short dry spells, but flowers better with occasional deep watering during prolonged drought.

Soil

Well-drained sandy or loamy soil; tolerates a range of soil pH but struggles in persistently wet ground.

Height

4-6 ft (1.2-1.8 m)

Spread

4-6 ft (1.2-1.8 m)

Flowers

Small golden-yellow flowers in upright clusters from spring into autumn; flowering can continue through much of the year in frost-free climates.

Foliage

Evergreen. Small, opposite, oval green leaves on slender stems; young stems may be reddish.

Growth

Moderate to fast in warm weather.

Care needed

Low

• Pollinators
• Drought tolerant
• Heat tolerant
• Low allergen

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

Difficulty

Moderate

Toughness

Fairly tough

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

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.5 ft (0.75 m)

3. After 2 years

   3 ft (1 m)

4. After 3 years

   4 ft (1.3 m)

5. After 5 years

   5 ft (1.5 m)

   full size

About 4 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

Growth rate

Fast

• Water deeply when the upper soil dries during the first growing season; avoid keeping the root zone constantly wet.
• Apply a light dose of balanced, slow-release fertiliser in spring if growth is weak; avoid heavy feeding.
• Spread 2-3 in (5-8 cm) of mulch over the root area, keeping it clear of the stems.
• Use a container with drainage holes and a free-draining potting mix where winter protection is needed.
• Move container plants into a bright, frost-free place before the first frost, and reduce watering over winter.

Pruning. In spring, once frost risk has passed, remove dead or frost-damaged stems and shorten straggly growth to healthy buds. Lightly trim after a flowering flush if needed, rather than repeatedly shearing off developing flower clusters.

Spring

After frost risk has passed, prune damaged growth and lightly feed plants that need it.

Late spring

Plant outdoors once the soil is warm, or gradually acclimatise overwintered containers to outdoor sun.

Summer

Check soil moisture during dry weather and water deeply when needed; containers need more frequent checks.

Summer

Take semi-ripe cuttings from healthy, non-flowering shoots.

Autumn

Move container plants under bright, frost-free cover before cold nights arrive.

Winter

Water sheltered plants sparingly without letting the root ball dry out completely; leave outdoor frost-damaged stems until spring.

• Plant as a loose, flowering hedge along a sunny path or boundary in frost-free gardens.
• Use in the middle or back of a warm-climate border, with blue or purple flowers to contrast with the yellow blooms.
• Grow in a large patio container where its long flowering season can be enjoyed and winter shelter is available.
• Mass several shrubs on a sunny, well-drained bank for a soft outline and repeated colour.

Garden styles it suits: Tropical, Modern tropical, Modern courtyard, Florida subtropical, Caribbean and Low-maintenance.

Plant it with: Blue plumbago, Mexican bush sage, Society garlic, Dwarf fountain grass and Agapanthus.

Wildlife: The flowers attract bees and other flower-visiting insects. Its branching growth can provide modest shelter for small garden wildlife.

• Frost damage: leaves and shoots may blacken after cold weather. Protect containers and wait until spring growth begins before cutting back outdoor plants.
• Root rot in wet soil: improve drainage, reduce watering and avoid planting where water collects.
• Sparse flowering and loose growth: move container plants into stronger sun, or reduce shade around established shrubs.
• Spider mites in hot, dry conditions or under cover: check for fine webbing and stippled leaves; rinse leaf undersides and use insecticidal soap if necessary, following the label.

Not known to be toxic to people, cats, dogs or horses, but reliable species-specific poisoning information is limited. It is not an edible plant; discourage pets and children from eating any part.

• Gold shower (Galphimia glauca)

  The two species are frequently confused in nursery labels. Galphimia gracilis sheds its petals after flowering, while Galphimia glauca retains its petals around the developing fruit.

The species name gracilis is Latin for slender or graceful, referring to the plant's delicate growth.

Propagation. Take semi-ripe stem cuttings in summer and root them in a moist, free-draining medium with gentle humidity. Seed is another option where mature seed is available.

Accepted botanical name

Galphimia gracilis

In the US and Canada

Introduced in the lower 48 states, Puerto Rico and US Virgin Islands.

Native range

Brazil Northeast, Colombia, El Salvador, Guatemala, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest, Nicaragua and Peru.

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