Bonsai Tonight

Stratifying pine seeds

Posted in Bonsai Development by Jonas Dupuich on April 7, 2015

If you’re looking to plant seeds this spring, now may be a good time to do it. Considering how warm this winter has been in Northern California, January may have been a good time to get started, but either way it’s not too late to start now – weather permitting.

Many seeds benefit from scarification – treatments designed to pierce, damage or otherwise weaken the seed coating – and stratification – any means of providing artificial cool and moist conditions conducive to germination.

Pine seeds can be scarified by applying hot water. Stratification can be achieved by refrigerating seeds before planting (see Pine seed prep and Pine seedlings for an overview; provides details and specific instructions for different varieties).

Missing from my previous posts on the topic are photos. Here are a few shots of how I pack up the seeds after soaking them for 1-2 days.

Pine seeds

Japanese black pine seeds – ready for the fridge

The moss is often sold as orchid moss or white sphagnum moss. I wet it and squeeze most of the water out before putting it in the bag. After a few minutes in the fridge, the bag fogs up.

Pine seeds

Condensation in the bag

This year I’m planting red pine, black pine from Shikoku, and Mikawa black pine seeds.

Pine seeds

Red and black pine seeds

After a full week in the fridge, I’ll plant them in a pot with bonsai soil and cover them with fine particles to keep them moist during germination. For details, see Planting pine seeds.

Pinching spring candles on black pine

Posted in Bonsai Development by Jonas Dupuich on March 31, 2015

The basic premise behind developing material for bonsai is straightforward: first build the trunk, then focus on the branches. When building the trunk, encourage vigorous growth to thicken the trunk rapidly. When focusing on branch development, encourage less vigorous growth to ensure good branch density. Sounds easy, but there may be a bit more to it than that. When making the transition from trunk development to branch development, many bonsai will be quite vigorous. What are some good strategies for decreasing vigor? A reduction of fertilizer sounds like a good idea, but reducing it too much can weaken trees. And when developing pines, it’s important to keep them strong enough to withstand decandling. Reducing sunlight or water is another strategy, but to keep trees healthy, plenty of sunlight and water are required. The main thing is to avoid over-watering at this stage as it can lead to excessively long needles. One way to slow down pines is to shorten the spring candles. After the candles begin to elongate, simply break off some portion of the candle with your fingers. How much to break off depends on how long the candles are. Here’s an example on an 11 year-old black pine. Young black pine

11 year-old black pine

The idea for this pine is to make a small-sized bonsai. As the trunk has reached the desired size, I can pinch the longer candles to reduce the amount of food the pine produces. Pinching a candle

First grab the section to be removed

Pinching a candle

Then snap it off

I shortened the longest candles on this pine by about half, but left the shorter candles alone. Young black pine

After reducing the longest candles

I could have reduced the longer ones a bit more, but I didn’t want to remove too much foliage at this point as I’ll have another opportunity to balance vigor come decandling time. Do note, candle pinching is distinct from what is commonly referred to as decandling. Whereas decandling is the removal of fully developed shoots in spring, pinching refers to the partial reduction of candles before the needles elongate. Once pines are further developed, it’s more rare for extra-long candles to develop as the vigor is generally better balanced in more mature trees. When these long shoots do show up, I snap them off.

Today marks post #600 – thanks for reading!

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Feed me!

Posted in Bonsai Development by Jonas Dupuich on March 13, 2015

What’s wrong with this picture?

Cork bark black pine

Cork bark black pine

The tree is growing, but there is no sign of fertilizer.

Cork bark black pine

With tea bags filled with cottonseed meal

That’s better. The sooner I can start fertilizing, the stronger I can make the tree by decandling time.

I enjoy seeing the male flowers on pine, despite the mess. Here is the tree from the back and sides.

Cork bark black pine

Left side

Cork bark black pine


Cork bark black pine

Right side

I usually start with 1-2 units of fertilizer for small sized trees and 3-4 units for larger trees. I treat young and middle-aged trees the same.

Black pine

11 year-old black pine

Black pine

21 year-old black pine

While it’s more common to hold off on fertilizing deciduous varieties to avoid long internodes and large leaves, I make some exceptions.

Japanese plum

Japanese plum

My plum is the first tree to show signs of growth each year, and if I don’t start feeding quickly, the leaves turn yellow.

Why mention fertilizer so early in the season? Because the sooner fertilizing begins, the more vigor can be produced in a given year. While this can be important for all varieties, it’s especially important for pines that are to be decandled as there’s only so much time between repotting and decandling.

I usually wait three weeks after repotting to begin fertilizing. My standard fertilizers are fish emulsion and cottonseed meal, but this year I’m planning to use a greater variety of fertilizers to ensure the trees get a broader variety of nutrients.

Is it time to start fertilizing in your garden?

Time for a smaller pot

Posted in Bonsai Development by Jonas Dupuich on March 10, 2015

First develop the trunk, then work on the branches. That’s how I think about bonsai development. If the trunk has yet to reach its final size, I use large pots and encourage vigorous growth. When I’m happy with the trunk, I move trees to smaller pots and focus on refinement.

A number of my black pines turn 11 this year. A few have reached the desired trunk size. I’ve been slowly removing large escape branches and am now ready to move the trees to smaller pots.

In general, if the soil is good, it’s easy to use a smaller pot as the root ball will have fine roots throughout. If not, the tree will have to stay in an intermediate-sized pot until enough fine roots develop to support the tree in a smaller space.

Here are two of the 11 year-old pines I repotted this winter – both were container grown.

Black pine

Exposed root black pine – 11 years old

Black pine

After repotting

Black pine

11 year-old black pine

Black pine


After repotting – note how the trunk looks larger in a smaller pot

Yes, Northern California is in the middle of a mild winter and most of my pines are already growing. As I repotted these trees about a month ago, I can start fertilizing now to make sure they’re strong enough to be decandled come spring.

Ever wondered what it’s like to be a bonsai apprentice in Japan? For those who haven’t done so already, feel free to submit questions to Juan Andrade, the Costa Rican bonsai artist studying at Aichi-en in Nagoya, Japan with Junichiro Tanaka, via AMA scheduled for later today (Wednesday Japan time) at Ask Bonsai Tonight.

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