Purple Orchid Tree

Scientific: Bauhinia variegata

Common: purple orchid tree

Family: Fabaceae (Leguminosae)

Origin: China, India (naturalized across southeast Asia.)

Pronounciation: Bow-HEN-ee-a var-a-ee-GA-ta

Hardiness zones

Sunset 13, 18-23

USDA 9-11

Landscape Use: A spring flowering accent or specimen tree for mesic or oasis-like landscape settings. Does not perform well in xeric landscapes that have a predominance of inorganic rock mulch.

Form & Character: Upright, rounded, subtropical, Spanish or oriental architecture, vulnerable.

Growth Habit: Woody, semi-evergreen, perennial tree, briefly deciduous in early/mid spring, moderate to 20 to 35 feet height with equal spread.

Foliage/texture: Orchid trees have rounded light green two-lobed leaves, strongly emarginated, that are up to 3 inches wide. In Phoenix, the leaves age prematurely each summer because of the extreme heat and usually become marginally necrotic during later summer and fall if they are not planted in mesic or green surroundings with plenty of supplemental irrigation. Purple orchid tree has a medium coarse texture.

Flowers & fruits: Orchid tree produces an intense array of large white, pink to purple tubular orchid-like flowers in terminal clusters while the tree is briefly deciduous during early spring; fruit is an elongated brown pod to 6 inches during summer.

Seasonal color: Flowers are displayed from early March through mid April.

Temperature: Heat-loving (except for those scorching Phoenix summer days when the air temperature rockets above 110oF), hardy to 22oF.

Light: Full sun to partial shade.

Soil: In central Arizona, desert alkaline soils will cause leaves to develop intervenal chlorosis caused by iron, zinc, and mangenese deficiencies. This is especially aggrevated by chronic wet, poorly-drained soil conditions. Apply micronutrient fertilizers, especially those in chelated form, in early spring to correct this problem. Orchid tree performs best in soils covered with turf or organic-based mulches.

Watering: Apply water at frequent and regular intervals especially during the summer.

Pruning: Purple orchid tree needs pruning and staking when young to promote structural integrity and a strong scaffold branch system if a single trunk tree is desired, elevate canopy base.....but don't raise the crown too high as trunk sunscald will occur!

Propagation: Cutting or seed

Disease and pests: None of significance. Local desert stressors on this tree are more from unrelenting abiotic factors such as summer heat and drought.

Additional comments: Orchid tree is an excellent small to medium size flowering accent tree that tends to look ragged and tattered when fruiting. Also, orchid tree sheds a moderate amount of liter, but the outstanding spring floral display easily compensates for the tree's otherwise moderate levels of litter. The cultivar 'Candida' has outstanding white flowers.

Orchid tree has somewhat smaller leaves and flowers and a more refined appearance compared with its robust and landscape loud cousin, Bauhinia x blakeana (Hong Kong orchid tree).

 

Trim it back hard, once the flowers have fallen, and fertilize with any good quality palm fertilizer - 12-6-8 from Bushel Stop is a good choice.

Fertilize now (March) and again in late June and once more in October. Use a cup of fertilizer for each inch of trunk at chest height, spreading the food out to the edges of the crown and no closer than one foot to the trunk.

 

I do not use palm food on these trees but rather acid loving plant food as is reccomended,(same used for azelia's or hybiscus) also in my research it said to feed in Oct. before blooming no other time mentioned?? and also to give them something for the yellowing, I use magnesium, we have no idea why one of our trees is on the scrawney side.