True Blue Butterfly Bush (Tree Form)

True Blue™ is the trade name for the hybrid butterfly bush ‘Bostulu’, with violet-blue flowers and silvery gray-green foliage. In tree form, its upright growth creates a focal point along a sunny border or patio. Its upright growth and long summer bloom bring color through the warmer part of the season. ## Cultivar and form The [Star® Roses and Plants profile](https://starrosesandplants.com/plants/true-blue-buddleia/) identifies True Blue as ‘Bostulu’ PP 25,708 and describes blue flowers, silver-green foliage, upright habit, summer-to-frost bloom, and butterfly attraction. The [Monrovia cultivar profile](https://www.monrovia.com/true-blue-summer-lilac.html) lists full sun, zones 5–10, and ordinary shrub size of 4–6 feet tall and wide. The exact [U.S. plant patent](https://patents.google.com/patent/USPP25708P2/en) describes violet-blue flowers, gray-green to green foliage, and upright-mounded habit; it confirms the grant date of July 14, 2015. ## Site and dimensions The tree form has a narrower trained outline than the ordinary shrub described in grower profiles, so place it where its standard canopy can develop without crowding. The cultivar is suited to full sun and USDA zones 5–10. The patent describes the cultivar’s characteristics but its nursery specimen dimensions are not mature garden measurements. ## Maintenance Monrovia advises watering when the top three inches of soil become dry. Keep the plant in a sunny site with well-drained soil and maintain a clear, balanced standard through selective pruning. Remove spent panicles to keep the plant tidy and protect the root zone while it establishes.