It’s been more than thirty years since I bought my first indoor bonsai tree and began my journey into this amazing hobby. One of the things that has helped me enormously is a funny quirk in my head that allows me to remember all the little details. Even now I remember everything about my special trees. Where they came from, every little thing I did along the way and how they responded to my actions. This also includes the effect of weather which, especially in the UK is an ever present phenomenon that has an impact upon our activities. Don’t assume that good weather is good for trees and bad weather is bad. Most hardy trees need the winter as much as they need the summer. What I have learned is that the weather is not to be trusted but trees are and will thrive regardless of what the sky throws at them.
Where that goes wrong, on occasions catastrophically so, is when we start messing with things we don’t really understand. Putting our impatience upon a tree and expecting a certain level of ‘performance’ allied with an ill founded and inexperienced understanding will cause problems. I despair at the amount of desperately sad plants I see being slowly tortured to death by fumbling hands, it genuinely breaks my heart, right at the outset I got into bonsai because I have a powerful love of trees and their place in the world and because I believe they can teach us how to be better people. Every day it saddens me to see suffering trees in our hobby wether that be through ignorance or the strutting pride of their owners. Since the advent of the internet things have become much worse as ignorance has spread faster than time honoured and long understood wisdom. Bonsai really is an anachronism in this fast moving modern age, though i would argue, so are we.
In my experience the single most destructive activity in bonsai cultivation is the unhealthy obsession folk seem to have with re-potting. I have written at GREAT length on the subject of Repotting Bonsai and the requirements of the growing media we choose to use in Choosing Soil For Bonsai Trees. I have also covered correct timing in When to Re-pot Bonsai. What I didn’t really cover was the effects of weather on the process and that’s where a good memory comes in handy.
Just a few days ago I was advising folk hang fire on re-potting. In the UK SPRING IS NOT February despite what the weather looked like and in spite of climate change pundits telling us that’s now normal. It’s certainly not unusual to have something of a false spring here. I have seen it in five of the last six years here on the east coast. As we all know it’s more likely to snow at easter that at Christmas. Creating beautiful bonsai trees is all about doing the absolute best we can for our trees and that means every choice has to be our best. Re-potting bonsai early will NOT make spring happen any sooner no matter how much we wish it would. When I started bonsai we would re-pot around end of March going into April and May. Today folk start right after Christmas and by end of March (still the optimum time for most deciduous species) it’s all over.
Most re-potting work is entirely unnecessary, especially for older trees, many of which will give their best after five or even ten years in the same pot undisturbed assuming we have the appropriate skill required to cultivate bonsai at that level which is rare. The obsession with ‘free drainage’ is entirely unhealthy and largely only appropriate to accelerated growth regimens used with raw material. Any recently re-potted bonsai has, by default, a well draining soil. For mature bonsai this phase has to be managed so as not to encourage too much coarse fast growth which can ruin a trees maturity and fine ramification. In time drainage will reduce as pore space within the soil is filled with root and normal care can resume. For mature bonsai, re-potting once drainage reduces looks like the work of a mad man to me and guarantees ultimate failure in the quest for old mature and magical bonsai.
Before I run myself down a rabbit hole with all that let me get back on subject. The weather was unseasonably warm here a couple of weeks ago but now we are back to normal. Gales, freezing rain, heavy daytime rain followed by hard overnight frosts and constant temperatures in single figures. Normal fare for an early British spring time. So if you were seduced into re-potting bonsai too early because of the nice weather some consideration needs to be given to those trees now. What might that be?
In the case of most, simply moving into a greenhouse seems ideal. If you have the facility it’s a good course of action. However be aware that warm temperatures may bring on fast growing varieties too soon and then moving them outside later in the year can cause problems, certainly not ideal. A closed greenhouse with little air circulation is also bad and will encourage fungal problems, particularly with overly wet soil and freshly cut roots. Putting trees in the shade is a seriously bad idea in the UK, they need sun to recover. The ideal situation for most species is under a light open cover with direct natural sunlight protected from the wind and rain. Soil should be kept just a little more dry than normal. In this situation the cold (for hardy plants) is immaterial. The primary concerns should be the wind and the wet. Control these aspects correctly and all will be well. As foliage develops a preventative fungal and pest control spray is a very good insurance.
Think carefully about re-potting, it’s important but largely misunderstood, mis-used and unnecessary and can prevent bonsai trees reaching their full potential. Learn your horticulture, time your actions correctly and consider after care, it’s just as important as the task itself.