Collecting and Repotting Quercus robur/English or European Oak Bonsai

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The leaves on all 4 trees remained turgid at all times, no leaves dropped and there was no dieback of any kind on any of the trees. At the time of writing (mid-October) one of these trees has finished going through its natural Autumn colouring, the others still have green leaves and are just beginning to turn to Autumn colour (as would be expected at this time of year).
One of the Oaks I collected in August was also one of those I had severely trenched in early June, this was found to have tremendous new fine root growth growing from the tips of every root that had been severed during the trenching 3 months earlier.

Oak bonsaiThis is an Oak collected 3 years ago and planted in my garden to grow on. In August it was lifted, bare-rooted, and 1/2 the rootball rootpruned.

This is the same Oak 10 weeks later, no visible dieback or ill-health has occurred. The Oak was planted into a perforated pond-basket and within 6 weeks new feeder roots could be seen growing through the basket perforations.

 


In conclusion.

Though this year has been a limited experiment using a small number of trees, the difference in the reaction of these trees has been so profound that I now firmly believe that it is advantageous to rootprune and collect Quercus robur during the growing season, when the ground is wet (after rain) and temperatures generally cool (day temps below 25C). (As the main growing period when temperatures are at their highest and rainfall at its lowest, I would hesitate interfering with the roots once the leaves have lost their red Spring colour until mid August when temperatures again begin to cool).
I collected only small rootballs to see how far I could push the trees before they failed; I would however thoroughly recommend that ordinarily, the maximum amount of rootball is collected and retained when planting the tree in a pot to recover.
Do use the method of submerging the potted tree into water after collection; it ensures that the leaves and shoots remain turgid.
It must be noted that my findings are with Quercus robur, the English or European Oak only and not with other Oak species. It is also worth reiterating that the majority of tree species should never be collected or rootpruned at anytime other than during early Spring. To do so often causes death or severe weakness in a tree.

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