Interspecific hybrid of Buddleja araucana and B. officinalis, with features intermediate between the species. Shrub 2–4 m tall. Branchlets, petioles and leaves densely stellate-tomentose. Branchlets rounded to sub-quadrangular. Leaf petiole generally short, up to 2–10 mm, blade ovate to elliptic, upper surface rugose, underside with tan coloured indumentum, 10–30 × 3–12 cm, apex acuminate or acute, base cuneate to rounded, margin serrate. Inflorescence consisting of 3–9 loose globose heads; calyx 2–5 mm, tomentose; corolla cream to yellow with a strong lilac flush, corolla tube up to 6–9 mm long and cylindrical, exterior tomentose, lobes often reflexed. Flowers mostly sterile. (Pers. obs.).
USDA Hardiness Zone 8-9
RHS Hardiness Rating H5
A hybrid raised by Steve Nevard, London, UK, from a cross of B. officinalis with B. araucana, two species originating from different continents; it was introduced into the Longstock Nursery Buddleia National Collection (Hampshire, UK) in the 1990s. ‘Winter Sun’ is a tall and vigorous evergreen shrub with large and felted foliage. The indumentum on the leaf undersides and branchlets is tan rather than white, a trait inherited from B. araucana (Stuart 2006).
The inflorescence consists of 3–9 balls of 20–30 flowers, and has an appearance similar to B. × weyeriana in shape. The individual flowers are multi-coloured, with a base yellow pigment flushed with lilac and mauve. It blooms in the early part of the season, February to April in the UK, the flower buds being formed the previous season and held dormant during the winter months.
‘Winter Sun’ is relatively hardy but requires some shelter from cold winds and a well-drained soil. A mild spring without hard frosts is necessary for it to bloom effectively outside, as the flower buds are easily damaged and may be lost during harsh conditions; for the flowering to be reliable, it is best kept undercover in a cool greenhouse during the winter months. ‘Winter Sun’ is uncommon in cultivation.