Chionanthus retusus ‘Tokyo Tower’
We’ve long admired Chionanthus retusus, Chinese fringe tree, as a bullet proof plant once established. Our first big planting at SFA goes all the way back to 1998 when 75 of the trees were planted along Wilson Drive next to the SFA Mast Arboretum. This planting was made in cooperation with Dr. David Kulhavy’s class in Forestry. While there was no drip irrigation on site, we did manage to drag some hoses across the street and give them a good soaking two times in 1998, once in 1999, and once in 2000. The planting has been on rainfall ever since. Even in 2010 and 2011 the trees were left unirrigated. While they weren’t happy in that long stretch of hundred degree days and incessant drought, they survived. One tough tree.
The form of the straight species is a bit problematic. Chinese fringe trees tend to sprawl with limbs going here and there. We trained our line of trees in the first few years to a single trunk and then let branching go as the tree wished, except for some occasional side branch removal. We’ve seen zero disease and insect problems. In Texas, the tree appears to better adapted to Central Texas and eastward. Soil pH should be a little on the acid side if possible. Sprinkler irrigation with alkaline or salty water results in leave burn. Foliage is very glossy and an attractive light green. While the tree flowers best in full sun, we’ve been impressed with tree performance even in part shade.
There’s one variety worthy of much greater use, ‘Tokyo Tower’. This Don Shadow introduction from Japan is very fastigiate. It’s a male with blooms that are quite large compared to the straight species. In East Texas, ‘Tokyo Tower’ appears to leaf out and bloom about a week after the straight species. The chilling requirement of ‘Tokyo Tower’ may prevent the clone from performing well in Zone 9 and 10. Darren Duling of Mercer Arboretum, Houston, Texas, reports that his trees failed to leaf out properly and there was die back. Linda Gay of Houston reports the same. Mike Arnold of Texas A and M University noted delayed foliation and poor growth at College Station, Texas. A few trees in southeast Texas are not in good health. Jimmy Turner at the Dallas Arboretum reports it looks good coming out this spring. Mark Weathington sees no problems at the JCR Arboretum. Mike Dirr notes delayed foliation in Athens. Gary Knox at the University of Florida has only container plants right now but at Quincy it appears to be late in pushing foliage. Keith Hansen in Tyler reports ‘Tokyo Tower’ is healthy and they accumulated about 1000 hours less than 45 degrees F there this winter. That would suggest we received about 800 hours chilling (just a guess) and in our location ‘Tokyo Tower’ looks fine, albeit with foliage emerging a bit late So, our conclusion is that ‘Tokyo Tower’ is a candidate for Zones 8 and lower.
It must be grafted and a couple of rooting experiments a few years ago here at SFA Gardens were a total failure. However, Mark Weathington of the JCR Arboretum reports they were able to get 40% take on cuttings taken in June and treated with 7500 PPM KIBA.
Our start of ‘Tokyo Tower’ came from Hidden Hollow Nursery in Tennessee and came in bareroot. Growth in the first year in the container is disappointing and leaves are characteristically quite small. However, the second year sees better growth and leaf size jumps. Chinese fringe tree has a propensity to grow only in the spring and fall, sitting quite still during the summer months in spite of good nutrition and irrigation. ‘Tokyo Tower’ is a unique small flowering fastigiate tree for the southern USA. Anyone ‘Tokyo Tower’ looking for a tough as nails columnar small flowering tree need look no further. It’s a winner.
David Creech, Director SFA Gardens