Buddleja davidii, commonly called butterfly bush, is a deciduous shrub that is native to thickets on mountain slopes, limestone outcrops, forest clearings and rocky stream banks in China. It has escaped gardens and naturalized in some states.
The plant is noted for its bushy habit, arching stems, showy/fragrant flowers, and vigorous growth. Spike-like terminal and axillary flower clusters bloom from early to late summer, sometimes to first frost. Flowers are densely clustered in showy cone-shaped panicles. In the wild, straight species flowers are lilac to purple with orange-yellow throats. Numerous named cultivars have been introduced over the years, expanding the range of flower colors to include pinks, yellows, whites and reds. Flowers (each to ½” long) are mildly fragrant, and, as the common name suggests, very attractive to butterflies.
Newly planted trees or shrubs require more frequent watering than established trees and shrubs. they should be watered at planting time and at these intervals: 1-2 weeks after planting, water daily. 3-12 weeks after planting, water every 2 to 3 days.
If your plant is not getting enough light, the most common sign is the yellowing and dropping of leaves, stunted leaf growth, elongated stems, and a dull-green color. If your plant is getting too much light, then its leaves will have singed tips, burned patches, or will be falling off (yikes!).
It is important to never remove more than a third of the foliage in any one year and to cut just above a node on the stem.
‘Black Knight’ Βutterfly Βush is more tolerant to cold than the typical species since its low temperature tolerance varies from -23 to -26 °C (-9.4 to -14.8 °F).
Choose a pot with drainage holes, which also ensures potting soil doesn't stay too wet after watering your houseplants. The excess can freely escape out the bottom of the container, allowing oxygen to make its way to plant roots.