Royal Poinciana tree Delonix regia produce bright orange/ red flowers in the spring and summer. They grow best in a spot that receives full sun and theyââ¬â¢re not frost tolerant...Royal Poincianas can grow up to 40 feet 12 metres tall and spread out 40 to 60 feet 12 to 18 metres wide so theyââ¬â¢re best suited to large gardens