Why is the shrub known as “Golden Showers”, “Rain-of-gold”, or Thryallis considered a great Florida-Friendly Landscaping™ approved plant? Flowering almost all year round, this graceful shrub is a low-maintenance evergreen that is a must for all full-sun locations. Let’s look at the various characteristics of this stunning shrub and how it can fit into your yard.
The Thryallis comes to us from Mexico and Central America. Unpruned, this upright evergreen shrub grows over five feet tall with a similar width. A real sun-lover, the Thryallis requires full sun for best flowering. Too much shade will cause the poor shrub to have leggy growth and few flowers – not very usefully ornamental. The small, one to two-inch long leaves provide a light green background for the tiny three-quarter-of-an-inch individual golden-yellow flowers that form clusters called racemes four to six inches long. Thryallis can be pruned to shape in March with the goal of removing no more than twenty-five percent of the plant. Care must be taken not to over-prune which can negatively affect the plant resulting in fewer flowers and/or thinning lower growth. Out-of-bound branches can be pruned anytime to keep this shrub compact and neatly rounded.
Use Thryallis spaced at least three feet apart in informal mass plantings, in borders, or even in large containers. This shrub can also be used as a loose hedge or simply a mound-like feature specimen in a mixed bed. The rain-of-gold is moderately drought tolerant but has low to no salt tolerance. Flowers can be expected in abundance from summer through fall with sporadic flowering at other times of the year.
Hardiness is pretty good with this shrub falling into USDA zones 9B through 11. If a frost/freeze damages Thryallis, it will normally grow back without much problem. They can actually be frozen back to the ground and grow back from the roots in extreme cases. If you need to replace old, leggy specimens, new plants are easily grown from seeds and/or cuttings. I have even seen many volunteer plants popping up from seed around mother plants which can be salvaged and reset as new shrubs. If you start your own from seeds, harvest the seeds while still green and expect flowers as soon as the plant is one-foot-tall and around six-months in age. If you want to start your own plants from cuttings, use softwood cuttings during the summer. Otherwise, the Thryallis is readily available at many local garden centers.
Yes, the Thryallis is a Florida-Friendly Landscaping™ recommended plant for a reason – it works as a sustainable woody flowering plant. Moderately fast-growing, Thryallis will pay-off in your landscape for years to come. The sun is out, so invest in some “golden showers” today for an abundance of flowers tomorrow! For more information on all types of flowering shrubs suitable in our area, or to ask a question, please visit https://www.facebook.com/CharlotteCountyExtension. You can also call the Master Gardener Volunteer Helpdesk on Mondays, Wednesdays, and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Ralph E. Mitchell is the Director/Horticulture Agent for UF/IFAS Extension Charlotte County. He can be reached at 941-764-4344 or ralph.mitchell@charlottecountyfl.gov. Connect with us on social media. Like us on Facebook @CharlotteCountyExtension and follow us on Instagram @ifascharco.
Resources:
Gilman, E. F. (1999) Galphimia glauca. The University of Florida Extension Service, IFAS.
UF/IFAS Gardening Solutions (2026) Thryallis. The University of Florida Extension Service, IFAS.
The Florida-Friendly Landscaping™ Guide to Plant Selection & Landscape Design (2022) The University of Florida Extension Services
Chase, L. (2026) Thryallis. South-Florida-Plant-Guide.com.
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