Princeton Purple Butterfly Bush

Princeton Purple is a full-sun butterfly bush with large clusters of deep-purple flowers. A regional shrub guide lists a mature size near 5 feet tall and wide and describes spring pruning; the cultivar can flower on new growth after trimming. ## Flowers and placement The [Colorado Tree Farm Nursery guide](https://www.coloradotreefarmnursery.com/wp-content/uploads/2022/03/Master-Shrub-Guide.pdf) identifies the exact cultivar as Buddleia davidii ‘Princeton Purple’, with large flower clusters that attract butterflies. The nursery’s [shrub profile](https://www.coloradotreefarmnursery.com/ornamental-shrub-description-guide/) lists flower spikes from July through September and a 5-foot height and spread. Plant it in full sun where the flowering shrub has room to develop. A [2011 European cultivar survey](https://www.researchgate.net/publication/283418774_Buddleja_davidii_en_hybriden_sortimentsonderzoek_en_keuringsrapport) lists Princeton Purple as an American selection and notes occasional confusion with ‘Dubonnet’. When clone identity matters, check the plant’s provenance. ## Maintenance Prune in early spring, since flowers form on new growth. Water during establishment and avoid persistently wet soil. In areas where butterfly bush self-seeds or is considered invasive, remove spent flower clusters or select a locally recommended alternative.