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Jim Lewis 09-02-2003 08:01 AM

[IBC] Care Tips for your Bonsai #3 - spring (LONG!)
Ahh Spring! When There's Never Enough Time to Do It All

For growers of bonsai, spring is the busy season. For some of
us the spring workload has been the impetus for reducing the size
of our tree collection as we find that we simply cannot do all
that must be done when buds start to swell.

It is easy to become impatient when the air starts to warm in
the late winter, especially for those of us with large
collections and so much to do. But here as in much else in
bonsai, patience can be a tree-saving virtue. Pull a tree from
its pot and snip at its roots too early, and an early spring
freeze may set it back years -- or worse.

You can make your spring easier by parceling out the chores over
the season.

Early Spring

There are spring things to do, even while the snow still lies
on the ground, or before you know that Jack Frost will make his
last visit for the winter. Here's a short list:

1. Clean pots. We've all got pots laying round with bits of
last year's soil in them, or with tartar-like crusts of calcium
around the rim. The last dull and still-chill days of winter are
ideal for making your pots look like new. Simple soap and water
does for the old dirt. The calcium deposits are another matter.

How tightly these deposits adhere to the pot depends, I think,
at least a little bit on the glaze used by the potter. Unglazed
(or matt-finished) pots are the most difficult to really clean.
The deposits seem to bond to the rougher surface. I have never
successfully managed to remove all traces of calcium deposit from
an unglazed pot. But steel wool and a good rub with mineral oil
will help at least to cover it up.

Smooth, glazed pots usually can be freed of calcium with a
caustic bathroom cleaner and a plastic-wire pot scrubber. Wear
rubber gloves. You may need to give a final burnishing -- dry --
with steel wool, especially if the surface is the least bit

While you're cleaning your pots, you also can be:

2. Planning which pots will go with which trees this year.
(This decision, of course, will help you determine which pots to
lavish the most elbow grease on.) You might want to refer to
David DeGroot's "Basic Bonsai design" as you make your plans.
His chapters on pot selection are the best coverage of the
subject I have seen.

As part of this pre-spring activity, of course, you will be:

3. Deciding which of your trees may need repotting this year --
and for what reason, or reasons. Except for small shohin-size
trees and young trees of many species, most bonsai only need
repotting once every 2-5 years or so. You may make an exception
for THE new pot for that azalea you repotted only last year, but
for the overall health of your trees, exceptions should be
infrequent. In general, deciduous trees and broad-leafed
evergreen trees need repotting more often than needle-leafed

Here is where maintaining an accurate record of your tree
collection is important. Once you have more than 4 or 5 trees,
remembering when you last repotted any one of them can be tough.
It becomes impossible once the collection exceeds 20 (or even 10)
trees. So, whether you keep these records on a computer, or a
spiral notebook, one of the bits of information you need to keep
is the date the tree was last repotted. (You also should note
growth habits of the roots to help you decide how often it might
need to be repotted.)

Mid Spring

But now the snow is gone, buds are swelling, the robins are back
on the lawn, and it is spring and time to repot!

If it has been more than 2 years since the last repot on a tree,
you will want to check on the condition of the tree's roots to
confirm whether this will be a repotting year for that tree or

The simplest test is to grasp the trunk and gently try to move
the tree from side to side. If it moves easily, and if the tree
is otherwise healthy, you don't need to repot this year; the
roots have yet to fill up the pot. If it doesn't move, you
should lift the tree from the pot and look at the roots. In most
pots a firm grip on the trunk and pulling straight up will lift
the root ball from the pot. On pots with convex sides, or lips
around the rim, you may need to run a thin blade around the edge
of the pot first. The tree and root ball should come free as a

Examine the roots. If they twist around the bottom of the root
ball, and even up the sides, you need to repot. If you see more
root than soil, you need to repot. But if there is soil on the
bottom and around the edges of the root ball, you can wait
another year. Make a note in your bonsai record for that tree,
then carefully replace the tree into its pot. You may need to
add a little soil at the bottom and around the edges to replace
soil that dropped away. Be certain that all air spaces have been

I won't go into the mechanics of repotting here. They're
covered (and illustrated) in some detail in almost all bonsai
books. In particular, see Sunset's "Bonsai: An Illustrated Guide
to an Ancient Art," the Brooklyn Botanic Garden's "Handbook on
Dwarfed Potted Trees: The Bonsai of Japan," Harry Tomlinson's
"The Complete Book of Bonsai" (available in pocket size as the
"RD Home Handbooks: Bonsai"), Herb Gustafson's "Bonsai Workshop,"
or others for excellent descriptions of the process.

Note that while many of these books imply that you should trim a
corresponding amount of top growth after you have trimmed the
roots, in my opinion this really isn't necessary on a healthy
tree that is acclimatized to life in a pot. On deciduous trees,
I usually snip the very tips of the branches -- perhaps a
millimeter or two, no more -- on the theory that this may promote
budding farther back on the branches and help improve the tree's
ramification. Of course trimming to maintain shape, or that
leads to major new design elements is another matter entirely.

If you are like me, spring is leaking into summer by the time
the necessary repotting is done -- and there always are trees
that just don't make it this year. Those, you carefully note in
your bonsai record book so they'll be first up NEXT spring.

Jerry Stowell's "The Beginner's Guide to American Bonsai" has a
fairly useful chart in one of its appendices that indicates when
some species of trees might best be repotted.

Other spring chores

But wait, there's more to do!

Spring is when the birds -- and bonsaiests -- begin to think
about reproduction. For bonsaiests, thoughts turn to cuttings,
air layers, and even seeds. Bonsai Today issues #8, #64 and #77
have excellent articles on growing cuttings, including a useful
table in issue #77. Air layering is covered in depth in Bonsai
Today #2, and almost as well in #33. The ABS Journals for both
spring and summer 2002 also deal with layering. Many bonsai
books also cover these subjects in some detail. See also the
Evergreen Gardenworks web page -- --
for excellent articles on propagation.

Spring isn't TOO late for transplanting from the ground to a
pot, though late winter would have been much better. You can
still transplant pines before their candles start elongating;
maples can be transplanted as buds leaf out, but beech, hornbeam
and hophornbeam are best transplanted to pots before any green
appears, so it may be too late. Hawthorn and other flowering
plants should be dug before flower buds burst. Tradition says to
move azalea after flowering, but that is only because most people
can't bear to see a spring without azalea blooms. They'll (the
azaleas) be happier if you debud them and transplant in the
spring like any other plant.

Spring cleaning is best done -- in the spring. Clean your
bonsai tables -- scrub off the winter mould left behind by cold,
wet weather and rotting leaves. Now that your empty pots are all
clean, scrub the crud off the sides and lips of pots that have
trees in them. Rake the soggy, dead leaves from your garden and
walkways and toss them on the compost heap -- they can help grow
bonsai some day in the future. This last cleanup will reduce the
likelihood of serious insect infestations later on.

In early spring -- about the time you're cleaning your empty
pots -- you should clean, oil, and sharpen your tools. Replace
those that have seen better days; dull, ill-fitting tools whose
blades no longer meet cleanly damage your trees. With the
exception of concave cutters (and, possibly, knob cutters) you do
NOT need to buy "bonsai tools." Many garden tools will do as
good a job for MUCH less cost.

Spring also is the time to get stocked up on fertilizer, and on
pesticides, if you use them.

While fertilizer may have a fairly long shelf life, many
pesticides -- even in tightly sealed packages or bottles -- can
degrade over the course of a year or two. If you are a chemist,
you may be able to figure out what these chemicals degrade to,
but most of us aren't -- and you don't want to spray an unknown
chemical on your trees. Take the old containers to a hazardous
waste disposal area and let the professionals dispose of them
properly. Then buy fresh.

Bugs show up in spring, too. The first on the scene will be the
"bad bugs." Predators don't arrive until they are confident of
finding something to eat. In spring, more than at any other time
in the growth cycle of your bonsai, the basic pesticide adage --
use the LEAST toxic method of control that works -- is especially
important. Leaves and roots are new, and tender; a chemical that
might not cause significant damage in summer may be a disaster
now. Springtime pest control is best limited to soap sprays
(except on maples!), horticultural oils (keep the trees out of
full sun for a few days), heavy sprays of water, and hand
picking. And remember, if you dose a tree with anything aimed at
killing every last possible pest, you're likely to damage the
plant. You're looking for control, not annihilation.

In spring, you also start fertilizing. Non-flowering plants
need a balanced fertilizer -- approximately equal amounts of
nitrogen, phosphorus and potassium. Occasionally you should use
a fertilizer with micronutrients, including chelated iron,
manganese and magnesium. (Other important micronutrients include
Zinc, Sulfur, Boron, Copper, and Sulfur.) Whether you use
"organic" or "inorganic" fertilizer has little importance in
bonsai nutrition. Most organic fertilizers, however, lack needed
micronutrients, so judicious use of both kinds is probably best.
Most authors suggest less nitrogen for flowering plants until
after they flower, but I don't think I would ever use a
fertilizer with no nitrogen. Even flowers need and use it.

Every two weeks is a good general springtime schedule for
fertilizing. For trees that I am pushing for growth, I will
fertilize every week until mid summer. Follow label directions.
Diluting to half strength is NOT needed. You can start
fertilizing within a week after a tree has been repotted --
sooner, if root work was limited. (An increasing number of
growers seem to fertilize immediately after root work. It
probably won't hurt.)

For its overall coverage of pesticide issues and fertilizing, I
like "Rodale's All-New Encyclopedia of Organic Gardening." It,
naturally enough, favors the organic side of things, but it
present a balanced coverage of both organic and inorganic
pesticides and fertilizers. All too many bonsai books spout
absolute nonsense on these subjects.

I don't wire in the spring. Trees grow too rapidly, and wires
quickly start digging into the bark. Since I actively dislike
wiring I don't want to have to do it more often than is
absolutely necessary. However, the chart in Stowell's book also
provides a suggested schedule for wiring.

Since spring only happens once a year, you have a limited amount
of time to do all that needs doing as everything springs to life
again. This busy season always makes me reconsider those winter
collecting trips -- at least until NEXT winter.

- Jim Lewis -

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