Green Japanese Maple

[cmsheehan]

A few pictures, a few observations and a few questions. Introducing my new Green Japanese Maple, purchased in May, 2025, my first maple bonsai. The company I purchased the tree from says it is 3-4 Years old.


The leaves have gotten quite burnt, we have had some extremely hot days recently here in Massachusetts ( zone 6a ) I made the mistake of misting the tree during the day and I believe that, combined with the brutal sun, was causing some damage. I have stopped misting during the day and moved the tree to a more suitable location that gets less direct sunlight.

Pruning: I understand large pruning should be done in the spring, but to keep internodes shorter, can I prune back longer internodes to reduce them any time of the growing season?

Soil and Pot: This tree was purchased in May 2025. Shortly after I repotted the tree into a larger pot that I drilled numerous additional holes in for drainage. My goal was to allow the roots to develop really well by using a mixture of Akadama, lava rock, and pummus. Now, I’m thinking I should have added some soil into the mix to help with some water retention. The way it is currently, water retention is almost zero (aside from what is absorbed into the rocks) Watching Peter Chan ( Herons Bonsai ) almost all of his maples are grown in soil and sometimes spagnum moss.

Should I consider adding some potting mix in with the bonsai mixture, and is the combination of the well draining bonsai mix and extremely well draining pot, a possible threat to the roots of the tree throughout the winter and colder months?

Fertilizer: I currently have used some succulent fertilizer ( 2-4-8 ) I’m wondering what others believe about how often one should fertilize Japanese Maple bonsai? Some people recommend to fertilize just once per year, in the spring. Other sources recommend fertilizing about once per month through the growing season, spring to late summer.

 

[Orion_metalhead]

Right now, Id do nothing but keep in in partial shade, water appropriately with your current mix, and wait til an appropriate time next year to repot. May is too late for repotting maples. If it is in full leaf a repot can be risky. I dont think you have a soil problem, I think you have a late repot-scorched full sun palmatum problem.

 

[Michael P]

Agree with Orion metalhead.

The leaf scorch was caused by full sun and high temperatures, not misting. It is perfectly safe and often helpful to mist or otherwise wet foliage in full sun. The myth that sun on wet foliage causes scorch was disproven many years ago but it still comes up often.

 

[Shibui]

Pruning: I understand large pruning should be done in the spring, but to keep internodes shorter, can I prune back longer internodes to reduce them any time of the growing season?

Pruning can be done right through the growing season. I frequently remove long Spring internodes late Spring or Summer to try to get shorter growth for better ramification.
Having said that, I'm not sure your tree needs pruning at this stage. It is very weak after a tough Summer. It's also still pretty skinny and removing growth won't help it get any thicker.
Have you decided on a tree shape yet? To my eye, the vertical lower trunk followed by a sharp kink with little taper in the trunk does not look natural or interesting.
A strong, stable root system in considered very important for good bonsai to show age and stability. It's not a great idea to style a bonsai until you know where the surface roots are.

Soil and Pot: This tree was purchased in May 2025. Shortly after I repotted the tree into a larger pot that I drilled numerous additional holes in for drainage. My goal was to allow the roots to develop really well by using a mixture of Akadama, lava rock, and pummus. Now, I’m thinking I should have added some soil into the mix to help with some water retention. The way it is currently, water retention is almost zero (aside from what is absorbed into the rocks) Watching Peter Chan ( Herons Bonsai ) almost all of his maples are grown in soil and sometimes spagnum moss.

Drainage/ soil aeration is very important for root health. That's why most of us use very open mixes for bonsai however, soil is a very personal choice as you can see from Herron's mix (BTW, I don't think that's actually 'soil' he uses, more likely an organic potting mix that may look like garden soil. It may work for him but may not be great for others. The soil mix needs to suit the way you water and care for your trees. Personally, I'd stick with the soil mix you have and learn to water to suit the soil rather than adding soil and risking root rot. The choice is yours.
Ditto for open pots.

Fertilizer: I currently have used some succulent fertilizer ( 2-4-8 ) I’m wondering what others believe about how often one should fertilize Japanese Maple bonsai? Some people recommend to fertilize just once per year, in the spring. Other sources recommend fertilizing about once per month through the growing season, spring to late summer.

Not sure who recommends fertilise once per year for bonsai. Regular watering leaches nutrients so we need to relace lost fert way more often than that to maintain healthy trees. We can get away with reduced fertiliser for really old, fully developed trees when we want to restrict growth but for developing trees it's more common to use plenty of high N fert to get the growth we need to build trunks and branches.
2-4-8 seems to be an odd ratio of NPK. Plants normally need more N that either P or K to grow well.
I use Osmocote in the potting soil for continuous background nutrient release with added liquid fert every 2-4 weeks through the growing season as well as occasional additions of organic pellets for variety.
Starving your trees might give you shorter internodes and reduced growth but it will take many more years to grow the branches and ramification that will make your bonsai into a desirable tree.

 

[darzuo]

I live in the same area as you, I would just leave it alone for now in a mostly shaded area, some dappled or early morning / late afternoon sun would be fine. I wouldn't worry about the soil mix as long as you can stay on top of watering and don't let the roots dry out, no need to add anything. The combination of too much sun with an untimely repot just stressed the tree out, but they're hardy enough that it should recover. I wouldn't prune at all for now, just water and let the tree recover

 

[cmsheehan]

Right now, Id do nothing but keep in in partial shade, water appropriately with your current mix, and wait til an appropriate time next year to repot. May is too late for repotting maples. If it is in full leaf a repot can be risky. I dont think you have a soil problem, I think you have a late repot-scorched full sun palmatum problem.

Thanks so much for your response! I didn’t realize May was too late for repotting.

 

[Wulfskaar]

Thanks so much for your response! I didn’t realize May was too late for repotting.

I have learned the ideal time is when the buds are extending and about to pop out leaves.

 

[cmsheehan]

Pruning can be done right through the growing season. I frequently remove long Spring internodes late Spring or Summer to try to get shorter growth for better ramification.
Having said that, I'm not sure your tree needs pruning at this stage. It is very weak after a tough Summer. It's also still pretty skinny and removing growth won't help it get any thicker.
Have you decided on a tree shape yet? To my eye, the vertical lower trunk followed by a sharp kink with little taper in the trunk does not look natural or interesting.
A strong, stable root system in considered very important for good bonsai to show age and stability. It's not a great idea to style a bonsai until you know where the surface roots are.


Drainage/ soil aeration is very important for root health. That's why most of us use very open mixes for bonsai however, soil is a very personal choice as you can see from Herron's mix (BTW, I don't think that's actually 'soil' he uses, more likely an organic potting mix that may look like garden soil. It may work for him but may not be great for others. The soil mix needs to suit the way you water and care for your trees. Personally, I'd stick with the soil mix you have and learn to water to suit the soil rather than adding soil and risking root rot. The choice is yours.
Ditto for open pots.


Not sure who recommends fertilise once per year for bonsai. Regular watering leaches nutrients so we need to relace lost fert way more often than that to maintain healthy trees. We can get away with reduced fertiliser for really old, fully developed trees when we want to restrict growth but for developing trees it's more common to use plenty of high N fert to get the growth we need to build trunks and branches.
2-4-8 seems to be an odd ratio of NPK. Plants normally need more N that either P or K to grow well.
I use Osmocote in the potting soil for continuous background nutrient release with added liquid fert every 2-4 weeks through the growing season as well as occasional additions of organic pellets for variety.
Starving your trees might give you shorter internodes and reduced growth but it will take many more years to grow the branches and ramification that will make your bonsai into a desirable tree.

Thank you for your detailed reply!
I think for now I will just let it grow and hopefully develop healthy roots before making any decisions on ultimate style. Yes, it is very small still, about 6” tall. The bend, I believe, is where the tree was grafted. I’m not expecting this to be a prize winner, and in fact was happy to find an inexpensive Japanese Maple, as my first tree. I expected there to be some learning curve and didn’t want to practice on a tree that I spent hundreds on.
The choice of fertilizer was a conscious one, I decided to start with something relatively weak, while the tree was in this current stressed state. I will purchase some more suitable food with a higher N ratio.
Appreciate all of your insight!

 

[Shibui]

The bend, I believe, is where the tree was grafted.

Does not appear to be grafted IMHO. More likely that bend is where it has been chopped at one stage. Pruning is one way of getting bends into trunks and branches.
You might consider tilting the trunk at next repotting to make the lower trunk more visually interesting and to soften that bend.
Something like this.

You will need to check the roots to make sure such a tilt is possible and practical before committing to the idea.

I’m not expecting this to be a prize winner, and in fact was happy to find an inexpensive Japanese Maple, as my first tree. I expected there to be some learning curve and didn’t want to practice on a tree that I spent hundreds on.

You should be aware that you have chosen to learn on a species that's quite challenging. From long experience, there are many much easier species to practice with.

 

[cmsheehan]

Does not appear to be grafted IMHO. More likely that bend is where it has been chopped at one stage. Pruning is one way of getting bends into trunks and branches.
You might consider tilting the trunk at next repotting to make the lower trunk more visually interesting and to soften that bend.
Something like this.
View attachment 608126
You will need to check the roots to make sure such a tilt is possible and practical before committing to the idea.


You should be aware that you have chosen to learn on a species that's quite challenging. From long experience, there are many much easier species to practice with.

Thank you for your response! I believe you’re correct, no graft, it was chopped there. Definitely a good idea, tilting the tree some, I will keep this in mind when the time comes.
I am definitely aware that these can be difficult, appreciate your feedback! I do have a Dwarf Jade (hard to kill, I know), a garden juniper, and a mugo pine, By no means am I claiming to be experienced. What I meant was, for 40 dollars, it’s a good Maple to practice with.
Thanks again!