Buddleja spp.
Light: Full sun to light afternoon shade. In Phoenix, provide afternoon protection for B. davidii; desert-adapted species tolerate stronger sun.
Water: Water deeply, then allow the upper several inches of soil to dry. B. davidii needs regular irrigation during Phoenix summers; established desert-adapted species need less. Avoid constantly wet soil.
Soil: Well-drained soil is essential. Desert-adapted species tolerate sandy, rocky, alkaline soils; modest compost additions benefit B. davidii in poor soil.
Mature size: Common garden selections reach 4–10 feet tall and 3–8 feet wide. Dwarf cultivars stay around 2–4 feet; some species grow larger.
Bloom: Generally spring through fall, depending on species and cultivar; extreme summer heat may reduce flowering.
Evergreen / deciduous: Varies by species: B. davidii is deciduous to semi-evergreen in Phoenix; B. marrubiifolia is generally evergreen.
Growth rate: Moderate to fast, depending on species, irrigation, and growing conditions.