I have a small hibiscus that I would like to train into a
tree with the twisted trunk and I have no idea how to go about that.
Please advise.
When you prune your hibiscus into a tree-like form with a single trunk,
it is called a standard. There are even braided topiary forms. To achieve
the twisted shape, you will probably need to create a support or frame.
The following general information on pruning comes from Tropical
Hibiscus:
“While the tropical hibiscus can be pruned any time, probably the ideal is
the earliest where the resulting tender new growth will be safe from cold
damage*. For shaping purposes, some growers will prune the longest third
of the branches and return in 4 to 6 weeks and prune the next longest
third. Only sharp, clean shears should be used. A clean cut should be
just above and angled down and away from an ‘eye’ or node. (A node is the
junction of a leaf and the stem. There is a small bud in this junction
that is activated after pruning.) Cutting above outward pointing “eyes”
will encourage growth in that direction. The new growth resulting from
pruning invigorates the plant and will provide a source for many new
blooms.”
The American Horticultural Society’s Pruning & Training (edited by Christopher Brickell and David Joyce, DK Publishing, 2011) describes the technique for creating a braided stem:
“Form a braided stem simply by braiding together three flexible young shoots. Select the strongest three on a multi-stemmed young plant, and remove the remainder. Single-stemmed plants can be cut back hard to produce multiple stems.”
The book also describes what is called a “barleysugar stem,” which may be more like the twist or spiral you envision: in this technique, “use a sturdy wooden pole with dowel pegs inserted in a spiral along its length. Train one or two stems around the pole, holding them in place by looping them beneath the dowels. Remove the pegs and the pole in sections when stem growth has hardened.”
Here is a link to Brooklyn Botanic Garden’s article on espalier forms, Special Cases: Pruning for Particular Purposes.
The Miller Library has a good selection of books on pruning and training,
and specifically on topiary. You can search the library’s catalog by clicking this link.