On April 28, 2022, Eric Schrader was the guest demonstrator for the Redwood Empire Bonsai Society (REBS) in Santa Rosa, California. Eric is a long time member and former president of the Bonsai Society of San Francisco (BSSF). He is a professional vendor, dba Bonsai For You; website https://www.bonsaify.com/. Eric has produced a number of instructional videos available on You Tube. Eric and Jonas Dupuich are the founders of the Pacific Bonsai Expo https://www.pacificbonsaiexpo.com/ scheduled for November 12 and 13, 2022, at the Bridge Yard, Oakland, California.
Eric’s demonstration was on seasonal work on Deciduous bonsai. He brought to the demo bonsai, one being a large Pomegranate and the other Seiju Elm. He first led a discussion of cutting back to the shape of the silhouette on the Pomegranate. The tree showed hardened new growth of shoots beyond the shape or silhouette. Eric cut each protruding shoot. He exercised caution to maintain the shape of the bonsai. No major cutting back, thinning of foliage or wiring took place. Eric discussed the difference of cutting vs. pinching. Cutting was used to shape and in branch development, whereas pinching was used to weaken and slow down growth of the branches.
He then moved onto the Seiju Elm, which would become the demo tree to be raffled at the conclusion. Common Name: Seiju Chinese Elm or Cork Bark Seiju Elm or Seiju Elm or Seiju Lacebark Elm. Ulmus Parvifolia ‘Seiju’ is the botanical name.
The demo tree was a Cork Bark Seiju Elm featuring a very rough bark trunk. The tree would measure about 12 inches in height. Eric pointed out a number of flaws in the demo tree. One, the nebari or visible surface roots of bonsai was straight on its base. There were a number of large roots exposed around the base of the tree. The trunk was thick without any taper towards the apical region. Primary branches were large and inflexible. A number of branches grew from a portion of trunk that appeared as a large fist on the tree. There was healthy foliage located in the apical region of the tree. Eric pointed out the foliage could be easily removed and regrown on the Seiju Elm.
Eric identified three potential remedies for the Seiju Elm.
- Air layer midrange up the trunk;
- Air layer upper range to the trunk;
- Remove most of the upper range to the trunk.
He then asked the members to select from among the three courses of action above. The members chose the air layering midrange up the trunk, the lesser in radical transformation of the demo tree. The demo became instruction on air layering the Seiju Elm.
Eric first cut and removed some of the exposed large roots surrounding the base of the trunk. He then took a sharp knife and began removing the cork bark, the process of air layering. Note: There are two air layering methods; ring method and tourniquet. Eric used the ring method on the demo tree.
The ring method works by cutting two slits around the branch at the area you want new roots to grow. Once you’ve made your slit marks, remove the bark, and you’re left with a shiny ring. The ring must be wide enough and deep enough for the tree to send out the rooting signal. Once you’re satisfied with your ring, cover it up entirely with a select soil medium and plastic. Eric used an 8 oz. plastic cup that he cut and fitted to the ring area of the trunk. He filled the cup with a medium mix of 80% coarse perlite and 20% coco coir. Then he used 16 gauge copper wire to affix the plastic cup to the trunk. Water will be needed to keep the medium mix moistened and allow new roots to grow. Note: the plastic cup used should allow one to see the new roots form. Sphagnum moss can be added to help keep the medium mix from drying out.
The lower portion of the trunk is removed once new roots have filled the plastic cup. Note: Elms tend to back bud easily at the cut site. The new buds will circle the wound area, and so branch development is possible for the lower portion of the trunk. Thus, one could make two small trees as a result of air layering.
Eric suggested that once the upper trunk is separated that the heavy, thick branches be thinned out.
Research online indicates that Seiju Elms are easy to grow as bonsai and can be an excellent choice for beginners as well as experienced levels.