Focus on Fall Pruning: Chojubai

It’s been a while since I’ve posted about the endearing and rambunctious flowering shrub Japanese Flowering Quince, ‘Chojubai’. It grows vigorously, flowers well, and stays small. And it’s a good subject for fall work overview.

Old Chojubai in the fall

Often we are laser focused on our bonsai when they are growing…and then as vaporously disengaged when they’re not. Bonsai can get less attention in the fall as it seems there is little happening. And yet it’s one of our most important seasons. 

Fall pruning is essential on the bonsai calendar as it directs and organizes spring growth, for both conifers and deciduous. There are three features to fall pruning:

• Thinning and reducing the tangle: Pruning selects what shoots remain to grow, limiting a snarl of shoots that destroy bonsai structure, and also focusing a plant’s energy on the shoots and buds we wish to emphasize for next year’s growth.
• Directional pruning: Identifying a bud and cutting in front of it will determine the direction the shoot grows next spring. Most shoot growth is from the last bud. It’s called ‘directional pruning’ as we’re fairly certain to get a shoot pushing from the bud we cut back to, and the shoot will grow in the direction the bud is pointing.
• Pushing more buds: By pruning in fall we can also activate interior buds, that then push in the spring. The reason is it creates a hormone imbalance in favor of cytokinins, that then initiate more buds. Why not cut in the spring? We can certainly do that, yet it tends to simply push the buds that are already there.

Over years, then, by the subtle influence of fall pruning as opposed to spring pruning, we can create bushier plants. This works on many types of plants, too, not just Chojubai.

As for directional pruning, Dwarf Flowering Quince ‘Chojubai’ offer many choices. The internodes are so short, about 1/4″, that very detailed selective scissoring is possible (unlike a Winter Hazel, where after a few inches of internode you might be ecstatic to find a bud).

Once the leaves have dropped, or most of them, is a prime time to trim your Chojubai.

Typical Chojubai extensions found in the fall, the result of summer growth after the trim in late spring. With nearly all its leaves dropped, this is ideal timing for the fall trim on this specimen.

Here’s an example in three photos of the trim possibilities on one shoot. This first bud is very small, hard to see. If we cut here, the bud points back into the tree—which will create a tangle of branches rather than a good branch flow to the exterior. So we won’t cut back to this one, even though the internode is nice and short.

This bud is going in the right direction, outside the tree, but the internode is rather long for this refined tree. 

Here’s the best option, on the opposite side of the same shoot—the bud is not growing into the tree, and the internode is nice and short, 1/4″. But we had three bud options within 1/2″, which is a lot of options.

A few general observations about growing Chojubai:

• This is a ‘Let’s go!’ plant, raring to be off with the least encouragement. Chojubai may be trimmed twice a year: once in late spring as growth hardens off, and again in fall.
• Loves fertilizer! And early. Should be one of the first plants fertilized in the garden, in early spring along with Black Pines. As the season advances, increase the dosage somewhat. 
• Loves water! Don’t let it get too dry, and use a deeper pot. 
• May flower several times a year, depending on how it’s feeling. Really, none of us know when a Chojubai will flower, but the main season seems to be early spring. 
• Ignore the yellow edging on the leaves; this is mosaic virus. It’s nearly assumed on the plant (the vector is aphids), most Chojubai have it, nothing gets rid of it, but, happily, it doesn’t seem to slow down the plant.
• Although Chojubai is one the hardiest flowering/deciduous plants, it is also one of the very first to start growing in early spring. It might be off and running when the snow is still flying, so definitely protect it from frosts in the spring. Once growing, even the hardiest plant is susceptible to frost damage.
• While a yardful of Chojubai can be odd (like my hoop house in the back), enjoy these plants as a whimsical counterpoint to your conifers. They also make great accent plants.

To see many older Chojubai along with some historical notes, try this post: Diminutive Jewels. At this point there are at least 6-7 posts about Chojubai in the archive, just type ‘Chojubai’ into the search field of the blog to find them-

Footnote: A big thanks to Gary Wood for many years of influencing my thinking about plant physiology.