I love bonsai and I’m also passionate about Australian Native Plants so it was natural for me to try to grow Aussie natives as bonsai. Originally I tried to use the Japanese timing and techniques and had many abrupt failures so gave up on natives as bonsai for many years. More recently, information from committed growers has led me back to growing natives as bonsai. Word was spreading that many of our natives dislike having roots pruned in the traditional winter/ spring period but thrive when repotted during the summer. Several years ago I set out to confirm this with a series of trials.
I grew a number of plants from a range of species and set about trial repottings each month over summer to try to ascertain the preferred months and techniques. The results have been quite clear. Almost all the trees that have been root pruned and repotted from October to February have survived and flourished. Several banksias that were repotted in March did not shoot well but sulked until the following summer and are still well behind their counterparts which were repotted earlier in summer. Results from my trials indicate that all the native species I have tried do better when repotted during late spring or summer. The presence of new shoots or active growth does not appear to matter. I have root pruned most species while they are actively growing without any problems. The following pictures illustrate the repotting procedure on a banksia clump. The notes on the pot indicate this was last repotted on 27.10.2011 and ¾ of the roots were removed at that time . These pictures were taken on Nov 30, 2012 and as you can see, well over half the roots were removed.
Banksia integrifolia clump
- Cut 1/3 off the bottom
and some off the sides
A little more off and about 1/4 of the roots remain
Potted up, watered in and back on the bench
You may have noted that this tree was placed straight back onto its place on the benches after repotting and watering it in. Most growers still adhere to the rule that newly repotted trees should be protected in shaded conditions until they have recovered. I believe that too much shade can actually slow the growth of shoots and roots so I try to give my trees. I have found that my trees do just as well (sometimes better) when put straight back into their places on the benches in full sunlight – as long as they are watered properly while new roots establish. Note – this works well for me here in my conditions. Growers are advised to trial any new techniques on expendable plants before changing established routine. The Australian Plants as Bonsai study group within Australian Plant Society has collected a wealth of information to try to unravel more of the nuances of growing Aussie natives as bonsai. You can help by contributing information from your experiences. http://anpsa.org.au/bonsai/index.html You can also see some inspirational photos of Aussie native bonsai at the National botanic gardens website http://www.anbg.gov.au/bonsai/index.html or at Canberra bonsai society website http://www.cbs.org.au/index.php?option=com_content&task=view&id=160&Itemid=79