It is advisable to seek advice when repotting
for the first time and if possible get someone who knows what
they are doing to demonstrate the process. Not everyone has access
to such luxuries so this article will take you through the steps
involved and hopefully make the fairly straightforward yet daunting
process a little easier.
Why repot - Bonsai need to be repotted in order to create growing
room in the pot. A healthy root system is one that has room to
expand slightly. For our purposes we need to create a fine root
system. In trimming branches we seek to create a nicely branching
structure dividing repeatedly from a thick branch down to delicate
buds. The same applies to the root system. The thick roots at
the base of the trunk are needed for visual effect but once hidden
under ground the subdivisions can begin in order to create as
many fine roots as possible. The amount of root that you remove
when repotting will reflect many things. The trees health should
be considered first and foremost. If your tree has been off colour
for a while then it is likely to be incorrect care that is causing
the problem. Removing large amounts of a root system that is already
struggling to maintain the tree will only make the problem worse.
In such cases repotting should be considered as a last resort.
For healthy trees, the size of pot should be the next consideration.
From a health point of view the pot needs to be large enough to
allow a seasons growth. If enough root cannot be removed safely
to allow this in the existing pot then consider moving to a slightly
larger pot. This is quite common especially with younger trees
that will naturally want to get bigger and whose vigour demands
slightly more growing room.
Pots are often chosen for artistic reasons and trees placed off
centre for aesthetic reasons. If moving a tree to a pot where
it will be off centre, the amount of roots on one side will probably
need to be reduced. If this means that the roots will be very
close to the side of the pot, moving to a slightly larger pot
will create the same effect whilst still allowing a little growing
room. Older and slower growing species will not need repotting
every year so assess whether it is totally necessary.
What you may need
Soil mixture - You will have read
the relevant articles on soil mixtures and will have whatever
mixture you are going to use to hand. The mix should be fairly
dry and you should make sure that you have enough.
Potting Mesh - to cover the drainage holes to prevent soil falling
out and to deter large insects from getting into the pot
Wire - In most cases the root ball should be securely fastened
into the pot. Use Aluminium or copper wire for this and also to
make hold the mesh in place.
Root Pruning Scissors - It is a good idea to have a separate pair
of scissors with sturdy blades just for root work. Fine trimming
scissors will soon be damaged in cutting through roots that are
caked in dirt and bits of grit.
Root Hook - Custom made root hooks are ideal for the job of teasing
out the root ball but chopsticks and knitting needles can also
Plastic bag - If you are planning on reusing the
same pot, have something handy to wrap around the root ball while
you prepare the pot
Ok so lets have a look at a practical example step by step.
Here we have a mountain Maple that is showing promise. I
t has the mother of all pruning scars running up the back
of the trunk but from the front and especially with leaves
on it is not obvious. It was last repotted 12 months ago
and will need repotting again this year not only because
the roots have fille dthe pot but also becausethe position
in the pot is not right. The visual weight of the tree is
slightly towards the right and it is leanig forward slightly
too much. It needs to be tilted back slightly and repositioned
slightly off centre to the left.
|We'll start with a bit of cleaning. The pot
market is awash now with some lovely chinese pots that are
excellent value for money but do have a tendency to leech
salts out of the clay. I am using a steel scourer to remove
the deposits. This is also the time to clean the moss from
the trunk and do a bit of weeding while everything is rock
steady in the pot.
Next we need to get the tree out of the pot. In most case
this is simply a cse of cutting any securing wires and lifting
it out. However id the pot has a slight lip as in this case
the edges will have to be loosened using a root hook, or
if need be a knife or in severe cases a folding saw.
Here you can see the scar at the back that you would never
had guessed was there if I hadn't mentioned it. This shows
that not everything has to be perfect and also acts as a
cautionary note when buying trees from photographs.
||Right there we have it free of the pot. You
can see how the roots have grown round the base of the rootball.
Note the use of an upturned plant pot, no expense spared here.
If you are going to be a while with the next step, bag up
the rootball to stop it drying out while we look at the pot.
Add or replace the mesh and secure with wire twisted into
a figure eight with tails. Also add new wires for securing
the tree. If you don't have the proper wire holes, use the
||As a rough guide you should be looking to comb
out about half the distance between the edge and the trunk.
Work on the sides all the way around and then examine the
roots for any major changes that need to be made. In this
case there are a few points that need addressing.
This is a close up of the front edge that highlights the
sort of things that need sorting before they become a problem
for the future.
A. The root on the left is quite thick and uniform in thickness.
It has a long bare section with a cluster of fibrous root
at the end. If left unattended the cluster will only get
thicker and there is little chance that new roots will emerge
from the bare section.
A side root at A is well formed and thinner than the rest
so the big root can be cut back to there.
B The crossing roots are undesirable. The thicker one can
C. The root on the left is very thick and unsightly. Below
it there are several thinner roots that will function better
in the future.
The left root was cut back to the side root
The centre root was removed all the way back to the base
as neither of the crossing roots amounted to much and were
contributing little or nothing horticulturally or visually
The right hand thick root was removed in favour of those
The result may seem a little drastic to the uninitiated
but this is the kind of bold steps that must be carried
out in order to create a workable rootball for the future.
Bear in mind that in each case no roots were removed without
first ensuring that there were better or equally viable
roots to continue the supply of nutrients to the tree.
||Back at the main task in hand the sides of the
rotball are trimmed all the way round. The amount to remove
should be somewhere beteen one third and hal the distance
from the old edge to the trunk In this case just under a half
was removed because this was the best position to create some
interesting sub divisions on the left hand side roots. Also
this tree was repotted last year in a similar fashion so is
trimmed not quite as far back as last year in order to make
the most of the branching of the roots that has occurred in
the previous year.
||A well maintained root ball will produce little
growth on the underside so it is just a case of removing the
loose soil and trimming the straggly bits
||Time to get our tree back in its pot.
Make a mound of potting micture in the centre of the pot.
I am using green dragon mix here, a mix of equal parts Akadama,
Kyodama and cat litter.Read all about it here.
Jiggle the tree on the mound to get the desired position and
height. Then secure with the wires.
||Introduce the fresh soil around
the roots working it bewtween the roots with a chopstick or
knitting needle. The idea is to allow the soil to flow between
the roots and any compaction should be avoided and a nice
loose soil mix will provide better conditions for re-growth
of the roots.
| Fill the pot and
then add moss to cover the holding wires. Give your newly
potted tree a good soaking to bed everything down and wash
away any dusty particles in the soil mix. Protect from frost
The exposed root ends will be sensitive to the cold for a
while so frost protection is a must. Do not feed for six weeks.
There are several schools of thought on this point but traditional
policy dictates avoidance of feeding while the tender new
roots are sprouting and resume feeding gradually with a weaker
than usual dose of fertiliser.
Every tree is different. While this procedure is a good basis
you will encounter the occasional dilemma. Field grown trees
that have been cultivated especially for the hobby will have
had some work done on the roots and the system will be fairly
compact. Others, particularly large collected trees have not
been told that there ultimate destiny is life in a pot and
have happily produced a root system in preparation for life
in the wild. Cases like this will need a common sense approach
where the needs of the tree must be placed first in order
to keep it alive. There is no point rushing and cutting off
too much root in order to get a tree into a pot. Re potting
must be approached in stages sometimes over a number of years
in order to train the tree to grow the correct type of roots
in abundance. Remember - if in doubt, ask
the heavens had opened and a hurried snapshot of the final result
will have to suffice for now
WHAT IS BONSAI? -
A brief introduction defining Bonsai
GETTING STARTED - A few simple
pointers to get you going
TOOLS AND TECHNIQUES
- An outline of the basic requirements
THE CHINESE ELM
- Everybody starts here, some home truths
FREQUENTLY ASKED QUESTIONS - A whimsical
look at some common problems
- What to do and when to do it
- DEVELOPING THE EYE - Slightly more advanced but essential
5 MINUTE RAFT PLANTING
- A simple project
THE ILLUSION OF
BONSAI - More food for thought
BONSAI SOIL - A look
at the essential of mixing a good Bonsai potting medium
BONSAI FEED -
An overview of feeding practices to get you thinking
LINKS TO OTHER SITES