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Ixora plants mostly only flower during the summer months. The individual flower heads will fade after four to six weeks of blooming. If you live in zone 9 or warmer, the plant is winter hardy and you can grow it as a perennial. It might even bloom a little bit on and off throughout the year, but it won't bloom in earnest again until the next summer.
You can read more about growing ixora here:https://www.gardeningknowhow.com/ornamental/shrubs/ixora/growing-ixora-shrubs.htm