December 2009 Plant of the Month —
Hardy Orange

Large vicious spines grow randomly on hardy orange's green branches. This makes it a standout in the winter landscape. (Photo by C. Reese.)
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Submitted by Jason Reeves   

Poncirus trifoliata has many common names. A few include hardy orange, bitter orange, trifoliate orange and mock orange tree.

Hardy orange is an old pass-along plant that is sometimes found growing at old farmsteads long after the house has rotted away.  This unique plant adds year-round interest to the landscape.  In the spring large fragrant creamy-white flowers are produced which lead to bitter-tasting, golf-ball-size, orange-like fragrant fruit that mature in September or October. Sparse dark green trifoliate summer foliage turns yellow in the fall before dropping off.  Large vicious spines grow randomly on green branches. This makes it a standout in the winter landscape. The branches are also useful as fresh cuts. 

Easily transplanted and drought tolerant, hardy orange can ultimately grow to a height of 20 feet but more commonly will reach 8-10 feet tall and wide.  They are easily grown from seed and will often germinate below the mother plant where the fruits have fallen. It is hardy to zone 6 and performs best in full sun to light shade in average to poor soil.

With its vicious spines it can be grown as a living fence.  Hardy orange can easily be pruned to form a dense hedge that will even contain cattle, much like osage-orange, or hedge apple (Maclura pomifera) trees, which were used by the early settlers for this purpose. 

The cultivar called ‘Flying Dragon’ is grown for its elaborate twisted branches and large spiny thorns. Its bare winter silhouette is especially breathtaking.  It can reach 8 to 12 feet tall and wide.  The seedlings from ‘Flying Dragon’ come mostly true to type.

Jason Reeves is curator and Ornamental Horticulture Research Associate with the UT AgResearch West Tennessee Research and Education Center in Jackson, Tennessee. He creates the various seasonal horticultural displays, conducts research on herbaceous and woody ornamentals, and supports various educational programs. The UT Gardens in Knoxville and Jackson are both open to the public. See http://utgardens.tennessee.edu/  and http://westtennessee.tennessee.edu/ornamentals/ for more information.

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Contact:
Jason Reeves, West Tennessee Research and Education Center,
731-424-1643

Patricia McDaniels, UTIA Marketing and Communications Services,
615-835-4570