Repotting Schedule (no, not that kind of schedule)

When do we repot different species? Not on a year-to-year basis, but if we do need to repot, when in the spring? This seems like a simple question, but after consulting my pile of books, my bonsai club, google, this forum, and watching a lot of Mirai Live archives, I’m still getting either no information or inconsistent information.

Ok, I mean of course. We repot in spring either before or just as new growth appears, and we protect from freezing.

But when specifically? Deciduous species are easy: just as the buds begin to swell. Pines, junipers, hinoki cypress, other conifers? I’m a little lost. Do we repot them earlier than deciduous species? Later? How late is too late? How do we know when it’s too late?

I’m in Richmond, VA, zone 7a/b and we JUST had our last freeze. The junipers are showing bright green tips, but no elongation. Pines seem like the candles are maybe just about to push, but I’m inexperienced enough that I can’t visually read them very well.

If anyone has some advice, or even better if you have links to any Mirai resources or other resources, I would SO, SO appreciate it.

If you JUST had your last freeze this is good time for all I would suggest. Check this info out for pines esp. the part about single flush and two flushes:
This is brief info but matches most of others I came across. Only thing you need to be careful is root prunning - can’t go to crazy. Hope that helps a bit :relaxed:

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For elongating species, like spruces and firs, the best time is just as the buds are starting to show a little green. If the buds are opening, it may be too late. You can also repot them late summer/early fall (allow at least 4-6 weeks before the first expected hard frost). Pines should be repotted before the candles open, although I collected a Ponderosa two years ago when the needles were beginning to open and it did fine. For junipers, Ryan says you have a window of a few weeks after the foliage starts changing from winter color to spring green.


Thanks to both of you for the info! Anyone know of any resources that talk about the horticultural/biological reasons for why we repot different species when we do?

larch need to be repotted before the buds show any sign of green
a good guide is to look at the buds daily in the spring and as they start to move the buds swell and get lighter in colour like little light bulbs just coming on

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It is all right here in Mirai Archives. Balance of water and oxygen is one reason to repot. Repotting the tree when it is in energy positive state, (do I have enough energy to sustain and give) and at a time of year that the tree can be protected from freeze or high temps. And never repot when tree is in an exhausted state (just after New push before new growth hardens off) These are all concepts that I have learned from Ryan and team. Ryan would ask first why are you reporting? Horticulture (H2O=O2) or Aesthetics?


Thanks Garrett. I have definitely been taking notes on the videos you’re referencing. I was more thinking about species-specific nuances, how late is too late into a bud push, etc, I feel that they’re not things that are specifically clear from the horticultural basics of energy generation and growth management. It only gives general guidelines.

Not sure where you live, but this is from my teacher Boon, we are in the Bay Area CA:

April, 2018 Vol. 21 Issue 4

This month’s topics: Elm

At the meeting : I will use the tree in my garden for display

Meeting date will Monday April 16th

Note: Members are required to participate in at least nine half-day
workshops a year.



During later winter – early spring, your trees should be watered once a day. The best time to water your trees is around 11-12 am. Watering too early, the trees may stay too dry in the afternoon. Watering in late evening, your trees will stay wet all night and it could cause fungus problem.

If you cannot water at proper time, it is better to water in the morning. And for small trees, use humidity tray to help your trees to stay moist during the day.

The best option is to set up an automatic watering system to water your collection.

You can water in the morning, and have the system come on again around 1 pm.

Make sure that your trees receive enough water in spring and summer. As the weather warm up, water trees more frequently with less amount of water, but never wait for your trees to completely dry out before watering. As a general rule, water when the top 30 percent of the soil is dry. Water needs vary by variety, soil mix, pot depth, and location in the yard — check each tree by using your finger or chopsticks and digging into the soil at the corner of the pot.

Akadama is a good moisture indicator. It turns darker brown when wet. Then water accordingly. Fruiting and flowering trees require extra water. It is recommended to cover the soil’s surface with white sphagnum moss to preserve moisture.

Note: Some people use wooden stick as a moisture gauge. The tree will stay too dry. It is not reliable because there is nothing to absorb the water from the wooden stick. It will appear wet longer than the condition of the soil in the pots. .

Insect and decease control

Spray for insects as a preventative. It may be too late when you see them. Try to avoid these surprises by spraying insecticide every month during the growing season.

Be careful with deciduous trees that still have tender leaves, insecticide or fungicide can burn new leaves.

I use Merit granule also as preventative. It is sprinkle lightly on the surface of the soil.

Be careful about using Bayer tree and shrub and 3 in one systemic. They are designed to use on the trees and shrubs in the ground. It can be too strong for your bonsai.


For the trees that were repotted, wait at least four weeks after repotting bonsai before fertilizing them.

For the trees in training, fertilize early and water more. The goal is to get thick trunk or branches. Do not worry about long internodes and big leaves or long needles. Big leaves and long needles help the trunk to grow large.

Technique will change after the tree is refined. That is when you deal with long internodes.

Organic fertilizer cakes made from rape seed or cotton seed meal (store-purchased or home-made) work well. Start with small amount and add a little bit more on once every week or two.

The best liquid organic fertilizer is fish emulsion.

Use it weekly ½ table spoon per gallon –

On the tree that we will remove spring growth or it will be defoliated, use a lot of fertilizers on your bonsai during growing season.

On high mountain trees and when the spring growth is kept, do not fertilize yet. If it is weak, fertilize lightly.

Time-release fertilizers (i.e. Osmocote )can be used but lightly. They are stronger and higher in NPK.

For mature deciduous trees, wait until new leaves harden off. Then fertilizing lightly. If you fertilize too early, or too much, both leaves and internodes grow large nd long.

Feed Japanese black pines heavily in spring to help the trees bud after decandling. For a twelve inch long pot, start with four to six fertilizer cakes and add one or 2 more every few weeks. When the surface starts to get full, remove old cakes and replace them with new ones. By the end of May, the surface of the pot should be covered with fertilizer.

Begin feeding white pines lightly when the new needles open, usually in May. Then skip it till it is harden off. Apply a light to moderate amount of fertilizer in summer to fall, starting with 4 cakes for a large tree and adding 4 more in late summer.

How late can you repot

The answer was – As long as the flowering cherry is still blooming, you can repot black pine.

Yasuo Mitsuya.

He did repot one black pine after the candles elongated in the beginning.

I would recommend observing your trees also. If the candles elongate and needles start to show, it may be too late.

Pinching: Whether or not a tree needs pinching is the most important question concerning your bonsai this time of the year. Before you start pinching your deciduous trees, ask yourself what stage of training the trees are in. Another question is what kind of deciduous tree do you have. Pinching techniques are often different from species to species.

Again, as a reminder, pinching should only be done on refined bonsai after branches and the overall structures have been developed.

If you pinch junipers too early, you will delay the development. You should let the junipers in training grow freely then wire new branches. Remove old leggy branches. Branches that have become too thick should be made into jin. Do not cut thick branches too close to the trunk since the scar will not heal over.

If your deciduous bonsai is in an early stage of training, let new buds grow freely and wire them after they harden off (early to mid summer around May-June). Because these buds grow fast, you may have to rewire your trees several times in a single season. By wiring young branches, you can add interesting curves where they are needed. In fall or early spring, cut these long branches back to a desired length so they can begin to grow freely again the following season. This treatment will strengthen your bonsai and promote good root development. Cutting those long shoots leaving 2-3 sets of buds, you create new interior branches.

Building structure of bonsai from the inside and work your way outward.

Most bonsai publications offer good information for pinching well developed bonsai. Here are some general guidelines:

Japanese Maples Use tweezers to remove the center buds leaving a single pair of new leaves. Do not pinch dwarf varieties

Trident Maples Cut off the elongated center of the bud beyond the cluster of newly opened leaves. If the new buds do not elongate, it may not be strong enough to be pinched. Feed it until you get the long shoots. Then you can pinch. If there is not elongate center, just cut large leaves. Do not pinch like Japanese maple

Beech Use tweezers to pinch back to two leaves after the buds open and the leaves start to unfold. Beeches are usually the last deciduous bonsai to open. Other option is to let it grow and cut back with scissors.

Scale Junipers Pinch only when strong pointed shoots (runners) grow about half an inch to one inch beyond the general outline of the branch, usually in April or May. without runner, the tree is not strong enough to be pinched

Needle Junipers (this apply to Juniper rigida only) Let new shoots elongate before using very sharp scissors to cut new growth back to a quarter inch or less. Do this from mid May to mid June.

Mixed foliage junipers (procumbent, San Jose, Foemina) cut strong shoots (runner)with scissors to another strong growing branches.

Elm Let the branches grow to about 10 leaves then cut back to 2-4 leaves. (keep more leaves for Seiju elm or Hokkaido elm as well as all the dwarf elm)

Zelkova Let the new branches grow to about 6-8 leaves. Then cut back to 2-3 leaves

Ficus let the new branches grow to 6-8 leaves and cut back to 2-3 leaves. Wait until the weather is warmer

Thinning: After pinching fully styled deciduous trees (refined trees only), the exterior will become full of leaves. Here are some tips for thinning this new growth. (Last month note, we talked about pinching technique between different species).

Japanese Maple After pinching, leave a pair of new leaves at each bud tip. If the tree is still very full, remove one leaf from each pair. Do not remove leaves from weak or interior branches. (Thinning the leaves is done after the leaves have hardened off.

Trident Maple Remove all large leaves and trim elongated shoots. Leave the interior leaves and small leaves alone. (the leaves should be hardened off also)

Beech Check the tree carefully from top to bottom, leaving only three leaves per new bud in strong areas, usually at the tree’s apex and exterior.

Thin our pines to balance the growth between strong and weak areas:

White Pine In the tree’s strong zone, break strong shoots leaving about 1/4 of the new needles per candle. In zones of medium strength, leave 1/2 to 3/4 of the new needles. Do not pinch weak areas or small buds. Start by breaking the strongest buds first.

Pinching with your finger. You can use two hand. Use thumb and index finger to hold the candle at the base. Use the thumb and index finger of the other hand to break it. Never use finger nail

After pinching candle on five needle pine. If the candles are short, they can be left alone, thin them in summer

Black Pine Pinching

Break strong candles to about the same length of the rest of the tree’s candles. Even if the tree’s growth is significantly unbalanced, break only the strongest candles. If the needles have already opened, use scissors to cut 1/4 to 1/2 of the large candles. Note: This is not black pine decandle. Decandle will be done in June. This is somewhat like five needle pine technique. But later in June/July, those spring candles will be completely removed


Deciduous trees in training : We can start wiring them toward the later part of the month. Let the new young branches grow freely. Wire and bend the branches at the base. We need only about 4 inches from the base of the branch. Then let the tree grows.

Conifer: When conifers are active the bark and the hardwood split easily. Avoid heavy bending this month. if you have to do it, use raffia to protect the bark from separating from hard wood.

Turning trees:

We should turn our trees 180 degrees once a month. Or 90 degree every other week.

This will keep our tree in god balance. Every branch will get the same amount of sunlight.

      • Workshop Information - - -
  •   all deciduous trees, Board leaves and fruiting flowering trees –light pruning and wiring.
  •   Junipers can be cut back and thin old foliage.  **very important to do it now***
  •   Japanese black pine can be work on carefully.  Be careful of the new

Wow. Thanks for sharing this @Garrett240!

Garrett that is some massively useful information! Thanks so much!

That is wonderful Thank you for sharing this - really helpful