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Spam Vs. Spam
Join Date: Jun-2004
Location: Hurstbridge
Country: DownUnda
Posts: 1,522
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Gday folks and Merry Xmas!
Sorry about the delay in getting this 2nd installation up, but it's been a busy time of year... Anyway, here's part 2. Please feel free 2 comment or ask questions.
Thanks.
FlyBri.
Root-Pruning and Repotting
There are a number of myths surrounding the ‘untouchable’ nature of Eucalypt roots – many folks believing that root-pruning a Euc will cause certain death. While this can be the case, especially with collected specimens, it is my experience that correct root-pruning techniques will more often than not produce happy, healthy potted Eucs. The main factors involved in ‘correct’ root-pruning are choice of material (see Material, above) and timing.
As with deciduous trees, Eucalypts are best repotted during dormancy, but as Eucs are evergreen, it is a little more difficult to determine when that is. Given enough water and light, Eucalypts will generally grow all year round. In nature, Eucs will tend to experience dormancy in late-summer, as this is often the driest time of year. During this time, there will be no new growth at the tips of branches, and all leaves will have hardened off.
There are a number of ways in which dormancy can be induced or simulated. The most natural way – and also the riskiest way, in my experience - is to show a Euc a little careful neglect, allowing it to gradually dry to the point where it experiences dormancy. (I have killed a couple of Eucs this way, and don’t recommend this method – it is simply too hard to tell precisely how much neglect is too much.) Eucalypts which are root-bound will also become dormant, but allowing a tree to reach such a condition can be hazardous. The safest and easiest method I have come across is to simulate dormancy by removing foliage from a Euc, since we are defining ‘dormancy’ as meaning that there is no new growth on a tree. The Koreshoffs recommend the removal of all foliage from a Euc which is to be repotted, either by singeing over a fire or by simply trimming with shears. This would be my suggestion when collecting Eucs from the wild, but I have found it unnecessary when dealing with specimens which are already adapted to container culture. I have had great success by simply cutting all branches back to one set of mature, hardened leaves during repotting, but this is entirely dependant on the health and volume of the roots that are to be pruned. For the inexperienced, I would suggest complete defoliation.
Another area of conjecture is the amount of roots which may be safely removed. The Koreshoffs talk of ‘severe’ root-pruning and ‘bare rooting or removing the outer section of the root ball only’. However, they do not speak in terms of the proportion of roots which may be removed. As a rule of thumb, I tend to go with the Bonsai standard of removing ⅓ to ½ of the existing roots, cutting out any strong tap roots. In cases where there is a large lignotuber present to sustain the tree during the trauma of repotting, I have successfully removed as much as ⅔ of the root mass.
It is commonly believed that a Eucalypt should never be repotted deeper than the previous soil level, for fear of the certain death of the tree. This is not something I care to challenge (though I do suspect that a young Euc would be more tolerant of deeper repotting than would a more mature tree). Eucs will happily withstand having surface roots exposed.
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