Thryallis (Galphimia glauca)

Thryallis Plant Features

Grow thryallis (Galphimia glauca) in your yard to add a beautiful ray of sunshine from this easy-care, sun-loving shrub. A beautiful tropical plant, thryallis is loved for its long bloom season; it blooms on and off all spring, summer, and fall in the North, and all year long in frost-free regions. It produces small spikes of beautiful golden-yellow flowers that give it a soft, almost cottage-garden texture. It's long season of bloom makes the plant a favorite for gardens and landscapes, as well as in container gardens to decorate decks and patios in cold-winter regions. 

Thryallis is hardy outdoors only in frost-free Zones 10 and 11. In these regions, as a landscaping shrub, it can grow up to 9 feet tall and 6 feet wide if unpruned. Because the leaves are relatively small, it responds well to pruning and is commonly used as a small hedge or back-of-the-border plant. It also can be pruned regular into topiary shapes. 

In cold-winter regions, thryallis typically only grows up to 5 feet tall and 4 feet wide in a season, making it perfect for use in container gardens, either by itself or in combination with heat-loving annuals and blooming tropicals (such as mounding mandevillas). A line of thryallis planted in pots along the edge of a deck or patio, for example, provides a lovely living wall full of golden-yellow color.

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Thryallis Growing Instructions

Grow thryallis in a spot that sees full sun (at least 6 to 8 hours of direct sun each day) to maximize its flowering potential. This sun-loving plant will tolerate part shade (areas with morning shade and afternoon sun), but is more likely to grow lanky and bloom less. 

Water thryallis when the top inch of the soil dries out. While it loves hot weather, it's not particularly drought tolerant. Too little water will reduce flowering -- especially if it's grown in pots or containers.   

Prune thryallis as necessary to keep its size and shape pleasing to you. The best time to prune is early spring, though you can trim it any time without harming the plant. The more you prune thryallis, the less it will bloom. 

When grown in the landscape or garden, thryallis typically doesn't need to be fertilized. But if you'd like to fertilize it for faster growth or more of its golden-yellow flowers -- or are growing it in container gardens -- you can use any general-purpose fertilizer. The plant isn't fussy! Do follow all application instructions on the fertilizer label to know how much fertilizer to use and how often to apply it. 

Thryallis is not intended for human or animal consumption.

  • Water

    Medium water needs

  • Light

    Outside: Sun

  • Colors

    Yellow

  • Special Features

    Attracts butterflies

    Deer/rabbit resistant

    Super-easy to grow

Complement your Thryallis

Crossandra
Plant low-growing crossandra around the base of beautiful thryallis for a smashing all-summer combo.

Angelonia
Complement thryallis' spikes of golden-yellow flowers with rich blue or purple heat-loving angelonia.

Cape Honeysuckle
Cape honeysuckle and thryallis are two blooming tropicals that bloom all summer and like sunny spots.

Texas Sage
Texas sage, another blooming tropical shrub, features lavender-blue flowers that make a lovely accent to thryallis.