This weekend marks an exciting time here at the Arboretum as our world-famous Bonsai collection makes its debut for the first time since mid-November of last year. In addition to having our Bonsai Exhibition Garden on full display again, we are also celebrating this Saturday the sixth annual World Bonsai Day, an international event dedicated to furthering bonsai awareness and appreciation worldwide. While we are proud to have these tiny, beautiful specimens back out on display for our visitors and members to enjoy, we also recognize that there may be some questions as to why these plants are removed from the exhibit in the first place. From space changes for our Winter Lights exhibit, to weather, to renovations, there are several reasons why the Arboretum’s Bonsai Exhibition Garden takes a break during winter and early spring.
Winter challenges
Perhaps at first, the bonsai specimens were not missed as much when they were removed in mid-November to allow room for the Arboretum’s Winter Lights displays. Beyond the space needs for the exhibit, most of the bonsai, in fact, are required to be kept inside during the colder winter months. Below is a short lesson on the concerns often faced by bonsai growers in wintertime:
When a plant is grown in a container – as bonsai are – the roots are not protected by the insulating effect of being in the earth and are more at the mercy of air temperature. Soil temperature is much more stable than air temperature, which can fluctuate 30 or 40 degrees from daytime to nighttime during the winter months. Roots are not well adapted to such dramatic changes, which can also lead to unhappy plants, or worse. So, when the temperature turns cold, bonsai plants require some protection. If the bonsai is of a tropical species – only a small number of the Arboretum’s collection are, it will be put in a greenhouse where the temperature can be maintained at 65 degrees or higher. If the plant is temperate in nature, it must be allowed to get cold and go dormant, but ideally, it will not be allowed to get too cold, thus the temperature will not vary as much. At the Arboretum, we have two different locations where we keep temperate plants in the winter. One is located in a large, walk-in refrigeration unit in the basement of the Bonsai Exhibition Garden pavilion, and the other is a hoop house structure that is covered with white polypropylene to protect the plants from the extremes of winter weather, which also allows them to still be cold and go dormant. While both of these overwintering locations provide the protection the bonsai need, unfortunately, they put them in a position where visitors cannot see them for many months.
A face-lift for the garden
Spring came early this year here at the Arboretum. All of the trees in the landscape have budded out, and the flowers are now falling off the dogwoods. A person might even plant their tomatoes now without much fear of having them nipped by a late frost, but still, there are not any bonsai on display in the Bonsai Exhibition Garden. Why is that?
Although the late arrival of the bonsai may be a frustration, the reason for it is actually a positive development. The Bonsai Exhibition Garden is currently getting a face-lift! Many of us still think of the garden as being “new,” but last October was the 10th anniversary of its opening. With a decade’s worth of well-managed growth, the plants in a landscape start to look pretty good. But a decade’s worth of wear and tear on the hardscape (the hard wearing materials in a built environment) typically produces an entirely different effect and calls for some maintenance attention.
We are thankful to dozens of bonsai enthusiasts and several bonsai clubs and societies for recently donating funds to refurbish parts of the Bonsai Exhibition Garden, including the railings, the wall capstones that enclose the garden space, and most importantly, the pavilion Douglas fir beams and timbers. Soon visitors will appreciate what a finely designed feature of the garden that pavilion really is.
The return of the bonsai
If you are among the many people who have come to the Arboretum in recent weeks and found that the bonsai are still on winter hiatus, make a note on your calendar to come back this Saturday, May 14. Not only will you enjoy the Arboretum’s excellent bonsai collection for the first time in six months, you will also see the garden spiffed up and looking its best. 
In addition, in honor of this Saturday’s World Bonsai Day, you will have the opportunity to learn more about the bonsai craft by watching a live demonstration from the Arboretum’s bonsai curator Arthur Joura. It will certainly be a big day for people who like little trees!
For more information about World Bonsai Day at The North Carolina Arboretum, click here.