Serissa slowly dying?!?!?!? HELP!!!

[Seattle Bonsai Newb]

Mr

Why is "Put it out in the sunlight." not an acceptable response?

Mr. Attmos, sir, well played.
It's not that "Put it out in the sunlight." is unacceptable (in my mind all responses are acceptable) it's more that it's questionable.
1. Tree's previous home had low light and high humidity (see pic below). Tree's current home has more light and similar humidity.
NOTE: Photo is from Asia Pacific Gardening, the happy homeland of likely most Serissa in US. Recommend to have a look at their website, very interesting.
2. Staff at APG say it's OK to have tree inside, just needs to be located near a window that gets good light and to water daily.
3. Serissa is a small tropical shrub, it undoubtedly evolved methods to survive in low (in shade of taller trees) and high (out of shade) light conditions, but probably not low humidity conditions.
4. In short, broad solutions broadly work, unless you happen to be in the minority. As a career aerospace problem-solver, could go into the method, theory and science of the problem-solving but might be out of scope in this forum. I can do a couple of paragraphs (it's simple) but only on request.
Look, lots of people complain about not being able to keep Serissa, yet they thrive in certain conditions. A more thorough/detailed explanation of their care would help many. These small trees are sold to 1000's of people per year, thinking they'll be able to keep them nearby INSIDE. I think it's completely possible (and so does APG) to keep serissas inside, just need to figure out the right combination. Having said all that, I'm looking for a suitable location for the tree outside as that may currently be its best bet going forward.

 

[Seattle Bonsai Newb]

We have. You just don’t want to hear it.

Indoor conditions are the root of your serissa’s current problems. Symptoms are of root issues and low indoor humidity and probably over watering and over fertilization for indoor conditions.

The Specific remedy that will clear most of this up is to get the tree outside.

not to belabor things but the tree should be outside. It’s not rocket science nor engineering

I have worked with Serissa and volunteer at the National Bonsai and Penjing Museum in Washington DC. Have cared for extensive Serissa plantings. Outside solves many problems. The tree may indeed drop leaves and sulk after being moved. Many plants to ficus does. For instance. They readjust and recover.

Inside environments are dry as deserts (relative humidity levels inside are below desert levels in some cases with forced ac and heating) air circulation is minimal and light is less than half oto a third or less of outdoor lighting
I’m speaking from 30 years of hands Ion experience with bonsai. Experience that includes caring ( and killing including Serissa) trying to keep trees inside. It’s an extremely hostile environment for plants compared to outdoors. Yours is showing that stress.

Your tree will be fine outside with increased humidity leaves will flatten out for instance. Dry conditions promote both crinkled leaves for lack of air moisture and accompanying mite infestations which can also cause the same symptoms

Biological problems can be caused by a lot of things including overcare by owners which contributes and amplifies problems. By placing the tree outside you eliminate a huge possible source of many issues

Plants did not evolve inside homes. They can only tolerate (some do it better than others) that environment. FWIW the long Japanese and Chinese traditions of bonsai don’t have “indoor trees”. It’s a western concept mostly developed as a marketing gimmick. Both cultures bring plantings inside sometime but the trees are outside again after only a few days.

Mr. rockm, sir,
I only have gratitude for the time and attention you and other posters have taken to address this issue. Please don't conflate my questioning for detail to be a judgement of your advice.
So, if the indoor condition can be controlled (humidity, light, temperature, wind?), wouldn't it be possible to keep serissas indoors?
BTW, have had two humidifiers (humidity measured around 70% most of the time) and a grow light on the tree for months, also Seattle humidity is generally/relatively high around 50% most days.
Thanks again for you experienced time and attention.
Kindest Regards,

 

[Attmos]

Mr

Mr. Attmos, sir, well played.
It's not that "Put it out in the sunlight." is unacceptable (in my mind all responses are acceptable) it's more that it's questionable.
1. Tree's previous home had low light and high humidity (see pic below). Tree's current home has more light and similar humidity.
NOTE: Photo is from Asia Pacific Gardening, the happy homeland of likely most Serissa in US. Recommend to have a look at their website, very interesting.
2. Staff at APG say it's OK to have tree inside, just needs to be located near a window that gets good light and to water daily.
3. Serissa is a small tropical shrub, it undoubtedly evolved methods to survive in low (in shade of taller trees) and high (out of shade) light conditions, but probably not low humidity conditions.
4. In short, broad solutions broadly work, unless you happen to be in the minority. As a career aerospace problem-solver, could go into the method, theory and science of the problem-solving but might be out of scope in this forum. I can do a couple of paragraphs (it's simple) but only on request.
Look, lots of people complain about not being able to keep Serissa, yet they thrive in certain conditions. A more thorough/detailed explanation of their care would help many. These small trees are sold to 1000's of people per year, thinking they'll be able to keep them nearby INSIDE. I think it's completely possible (and so does APG) to keep serissas inside, just need to figure out the right combination. Having said all that, I'm looking for a suitable location for the tree outside as that may currently be its best bet going forward.

Ok, well, if you're going to keep it inside...
~find a grow light for it...... even the shaded areas outdoors have many orders of magnitude more light than a window seat indoors
~maybe build or buy an attractive indoor glass greenhouse to maintain humidity
~don't water it daily...... water when the soil has dried out to about an inch below the surface, keeping it moist but not wet....... this might help the fertilizer burn as well as any root problems you have.

I have next to no experience, and absolutely none with that plant, so...

 

[darzuo]

Mr

Mr. Attmos, sir, well played.
It's not that "Put it out in the sunlight." is unacceptable (in my mind all responses are acceptable) it's more that it's questionable.
1. Tree's previous home had low light and high humidity (see pic below). Tree's current home has more light and similar humidity.
NOTE: Photo is from Asia Pacific Gardening, the happy homeland of likely most Serissa in US. Recommend to have a look at their website, very interesting.
2. Staff at APG say it's OK to have tree inside, just needs to be located near a window that gets good light and to water daily.
3. Serissa is a small tropical shrub, it undoubtedly evolved methods to survive in low (in shade of taller trees) and high (out of shade) light conditions, but probably not low humidity conditions.
4. In short, broad solutions broadly work, unless you happen to be in the minority. As a career aerospace problem-solver, could go into the method, theory and science of the problem-solving but might be out of scope in this forum. I can do a couple of paragraphs (it's simple) but only on request.
Look, lots of people complain about not being able to keep Serissa, yet they thrive in certain conditions. A more thorough/detailed explanation of their care would help many. These small trees are sold to 1000's of people per year, thinking they'll be able to keep them nearby INSIDE. I think it's completely possible (and so does APG) to keep serissas inside, just need to figure out the right combination. Having said all that, I'm looking for a suitable location for the tree outside as that may currently be its best bet going forward.

I mentioned it earlier, not sure if you read, but the sun is VERY strong. I would read this beginners post if you want more details, but outdoors in full shade gives more photosynthetic energy to plants than the majority of grow lights can. Your eyes naturally adjust to outdoor conditions so it may not seem all that bright, but the equivalent grow light in your house would need to be extremely bright (to our eyes). Most cheap grow lights are made to look nice in our homes, and it's rather uncomfortable to have a light in the corner of a room blinding us throughout the day. Maybe you could share the current grow light you have. There are some indoor growers here with advanced setups that know more about grow lights. High humidity is fine (and probably preferable for most tropicals), but it needs to be done in a proper way indoors. Almost all greenhouses with high humidity also have a ton of fans to ensure proper circulation and fresh air so that trees don't have fungal issues. This is another issue altogether, but these are businesses after all and a cute little tree you can keep on your desk is much easier to sell someone. Don't need to look much further than the thousands of poor juniper "bonsai" that have perished indoors.

In short, keeping it inside with poor air circulation and less energy to grow properly is causing it to struggle. It is possible to keep them thriving indoors with the proper setup, but said proper setup is more akin to a room dedicated to growing trees with proper humidity with circulation, and quality (expensive) grow lights. I think someone here mentioned a space like this they had worked in, and you needed sunglasses in there. Otherwise, trees may survive indoors, but will rarely truly thrive. Bottom line is that it seems like your tree isn't thriving, so we're all suggesting you take it outside.

 

[rockm]

Mr. rockm, sir,
I only have gratitude for the time and attention you and other posters have taken to address this issue. Please don't conflate my questioning for detail to be a judgement of your advice.
So, if the indoor condition can be controlled (humidity, light, temperature, wind?), wouldn't it be possible to keep serissas indoors?
BTW, have had two humidifiers (humidity measured around 70% most of the time) and a grow light on the tree for months, also Seattle humidity is generally/relatively high around 50% most days.
Thanks again for you experienced time and attention.
Kindest Regards,

Indoor accommodations can work, but not for any real extended time (like a couple of years--maybe longer, maybe much less). You simply can't replicate outdoor conditions indoors no matter how much money and effort you throw at trying to. When i started out, I used to have many "indoor" species, ficus, serissa, Australian brush cherry, schefflera. A lot of endless tail chasing trying to "cure" them of the inevitable disease and decline by insisting on keeping them indoors all year. I ditched most of them for "outdoor" trees after it just wore me out and I got tired of the cycle of healthy tree turning to a dead stick in a few months. I turned the corner on using temperate zone species after I simply plunked an ailing ficus from inside into direct summer sun outside on my southern facing deck and left it alone. It took a couple of weeks to adjust, but after that it took off like a weed, sending out five foot long shoots of leaves that had to pruned back three times before autumn arrived and I brought it back inside for the winter. It limped along and didn't grow until I put back outside in late April...

In the time you take keeping your tree inside, you tree will decline, getting weaker, dropping leaves etc.. You're already seeing evidence of that decline, you're just not recognizing it. Indoor conditions are controllable but those controls generally center around people not plants. Two humidifiers are great Eight or nine in an enclosed room would be better. Two humidifiers that keep a constant home wide or even room wide consistent humidity of 70 percent would mean mold, fungus and wet walls in the house. Grow lights do help, but unless you're using commercial grade high intensity lighting like those used in indoor agriculture set ups--for the Devils' lettuce primarily --your plant is still getting mostly inadequate light.

The bottom line in all this is that you're complicating things cost and experience wise by insisting on keeping the tree indoors when growing conditions outside offer a mostly cost-free and hassle-free and more effective option for the tree. FWIW, serissa (which is also called Japanese boxthorn) is a relatively newer species being used for bonsai. It is mostly confined to mass produced mass market sellers as its flowers "sell" the tree easily. It is, however, one of the more difficult species to keep. Keeping it indoors when it could be outside gaining strength to make it through winter indoors under artificial lighting and central heating adds to that difficulty. FWIW, the serissa forest at the National Arboretum and Penjing Museum is outside in mostly full sun all summer. It grows extremely vigorously outside here in the DC area. I've trimmed it back at least once in June after it pushed two foot extension growth. A stock photo of that Japanese boxthorn (serissa) forest is below.

I seem to remember back when first posted you said this was your second serissa. What happened to the first one?

Whatever the story, most new owners kill their first tree (s) because of overcare and misunderstanding. To be frank, I Wouldn't get too attached to the serissa. If you want a bonsai candidate that will stand up more inside, look at ficus.

 

[Seattle Bonsai Newb]

I mentioned it earlier, not sure if you read, but the sun is VERY strong. I would read this beginners post if you want more details, but outdoors in full shade gives more photosynthetic energy to plants than the majority of grow lights can. Your eyes naturally adjust to outdoor conditions so it may not seem all that bright, but the equivalent grow light in your house would need to be extremely bright (to our eyes). Most cheap grow lights are made to look nice in our homes, and it's rather uncomfortable to have a light in the corner of a room blinding us throughout the day. Maybe you could share the current grow light you have. There are some indoor growers here with advanced setups that know more about grow lights. High humidity is fine (and probably preferable for most tropicals), but it needs to be done in a proper way indoors. Almost all greenhouses with high humidity also have a ton of fans to ensure proper circulation and fresh air so that trees don't have fungal issues. This is another issue altogether, but these are businesses after all and a cute little tree you can keep on your desk is much easier to sell someone. Don't need to look much further than the thousands of poor juniper "bonsai" that have perished indoors.

In short, keeping it inside with poor air circulation and less energy to grow properly is causing it to struggle. It is possible to keep them thriving indoors with the proper setup, but said proper setup is more akin to a room dedicated to growing trees with proper humidity with circulation, and quality (expensive) grow lights. I think someone here mentioned a space like this they had worked in, and you needed sunglasses in there. Otherwise, trees may survive indoors, but will rarely truly thrive. Bottom line is that it seems like your tree isn't thriving, so we're all suggesting you take it outside.

Mr. darzuo, sir,
Thanks again for your time and attention in this matter.
Grow light is QvvCev mdl 200SMD-P`30-XJ - 8W full spectrum https://latinafy.com/products/qvvce...bulbs-e27-base-8w-full-spectrum-yellow-light/
Don't recall seeing fans aimed at trees at APG, see photo above.
Light meter indicates about 5000 lux on tree at grow light and 1500 lux (cloudy day) at location chosen (some sun, mostly shady, for now) for outdoor living. Next time I'm in the area of Asia Pacific Gardening, will take light meter readings in their shade house. Using my eye-crometer, light intensity at APG environment is somewhat low, but will see what light meter says.
Not arguing, but I suspect (based on what I've found so far) the "missing factor" killing or thriving serissas may be a combination of temperature cycling, light intensity cycling, air movement and humidity (or lack of). My Spidy Sense is telling me serissa need a good chill at night, good to intense light and high humidity but not ruling out anything.
Sometimes, whining long enough about something can lead to a solution, please forgive my persistence.
Thanks again for your time and attention.

 

[SeanS]

I’d put it outside

 

[Seattle Bonsai Newb]

Indoor accommodations can work, but not for any real extended time (like a couple of years--maybe longer, maybe much less). You simply can't replicate outdoor conditions indoors no matter how much money and effort you throw at trying to. When i started out, I used to have many "indoor" species, ficus, serissa, Australian brush cherry, schefflera. A lot of endless tail chasing trying to "cure" them of the inevitable disease and decline by insisting on keeping them indoors all year. I ditched most of them for "outdoor" trees after it just wore me out and I got tired of the cycle of healthy tree turning to a dead stick in a few months. I turned the corner on using temperate zone species after I simply plunked an ailing ficus from inside into direct summer sun outside on my southern facing deck and left it alone. It took a couple of weeks to adjust, but after that it took off like a weed, sending out five foot long shoots of leaves that had to pruned back three times before autumn arrived and I brought it back inside for the winter. It limped along and didn't grow until I put back outside in late April...

In the time you take keeping your tree inside, you tree will decline, getting weaker, dropping leaves etc.. You're already seeing evidence of that decline, you're just not recognizing it. Indoor conditions are controllable but those controls generally center around people not plants. Two humidifiers are great Eight or nine in an enclosed room would be better. Two humidifiers that keep a constant home wide or even room wide consistent humidity of 70 percent would mean mold, fungus and wet walls in the house. Grow lights do help, but unless you're using commercial grade high intensity lighting like those used in indoor agriculture set ups--for the Devils' lettuce primarily --your plant is still getting mostly inadequate light.

The bottom line in all this is that you're complicating things cost and experience wise by insisting on keeping the tree indoors when growing conditions outside offer a mostly cost-free and hassle-free and more effective option for the tree. FWIW, serissa (which is also called Japanese boxthorn) is a relatively newer species being used for bonsai. It is mostly confined to mass produced mass market sellers as its flowers "sell" the tree easily. It is, however, one of the more difficult species to keep. Keeping it indoors when it could be outside gaining strength to make it through winter indoors under artificial lighting and central heating adds to that difficulty. FWIW, the serissa forest at the National Arboretum and Penjing Museum is outside in mostly full sun all summer. It grows extremely vigorously outside here in the DC area. I've trimmed it back at least once in June after it pushed two foot extension growth. A stock photo of that Japanese boxthorn (serissa) forest is below.

I seem to remember back when first posted you said this was your second serissa. What happened to the first one?

Whatever the story, most new owners kill their first tree (s) because of overcare and misunderstanding. To be frank, I Wouldn't get too attached to the serissa. If you want a bonsai candidate that will stand up more inside, look at ficus.

View attachment 612575

Mr. rockm, sir,
Thanks again for your response. You're bang-on regarding hucking-around with the plant to get it to thrive inside. Serissa is that first plant, I've not been able to grow/thrive inside. Likely whatever the "hidden factor" is that makes serissa thrive/die (temperature cycling?) is not possible or economical for amateurs to recreate indoors.
Regarding the first serissa, had been keeping the plant indoor thinking that figuring out care and infrastructure might take some time. When the plant got weak, took it back to the nursery for 6 week rehab which worked the first time, but not the 2nd time. Pretty sure the tree was alive yet weak when it returned to the nursery the 2nd time. Have spent way too much time hucking around with the plants. The perfect trap engineers - an insolvable problem.
Regarding "overcare" as a root cause for killing Serissa, I would suggest that lack of clear/complete/detailed care instructions is likely at the top of the list.
Kindest Regards.

 

[rockm]

Mr. darzuo, sir,
Thanks again for your time and attention in this matter.
Grow light is QvvCev mdl 200SMD-P`30-XJ - 8W full spectrum https://latinafy.com/products/qvvce...bulbs-e27-base-8w-full-spectrum-yellow-light/
Don't recall seeing fans aimed at trees at APG, see photo above.
Light meter indicates about 5000 lux on tree at grow light and 1500 lux (cloudy day) at location chosen (some sun, mostly shady, for now) for outdoor living. Next time I'm in the area of Asia Pacific Gardening, will take light meter readings in their shade house. Using my eye-crometer, light intensity at APG environment is somewhat low, but will see what light meter says.
Not arguing, but I suspect (based on what I've found so far) the "missing factor" killing or thriving serissas may be a combination of temperature cycling, light intensity cycling, air movement and humidity (or lack of). My Spidy Sense is telling me serissa need a good chill at night, good to intense light and high humidity but not ruling out anything.
Sometimes, whining long enough about something can lead to a solution, please forgive my persistence.
Thanks again for your time and attention.

Mr. rockm, sir,
Thanks again for your response. You're bang-on regarding hucking-around with the plant to get it to thrive inside. Serissa is that first plant, I've not been able to grow/thrive inside. Likely whatever the "hidden factor" is that makes serissa thrive/die (temperature cycling?) is not possible or economical for amateurs to recreate indoors.
Regarding the first serissa, had been keeping the plant indoor thinking that figuring out care and infrastructure might take some time. When the plant got weak, took it back to the nursery for 6 week rehab which worked the first time, but not the 2nd time. Pretty sure the tree was alive yet weak when it returned to the nursery the 2nd time. Have spent way too much time hucking around with the plants. The perfect trap engineers - an insolvable problem.
Regarding "overcare" as a root cause for killing Serissa, I would suggest that lack of clear/complete/detailed care instructions is likely at the top of the list.
Kindest Regards.

That is part of the plan with Serissa. Sellers get return customers for dead Serissa I say that only half joking.

 

[rusticana]

Why is "Put it out in the sunlight." not an acceptable response?

I don't know why I'm chiming in here. Ha! But it's important to introduce plants back outside gradually. I've even scorched a yucca. I'm not a scientist but I think a plant indoors will be set up to absorb as much light possible where as ones outside will want protection from the sun. I put mine in the shade or with a table cloth over them to climatize.

 

[Stormwater]

every serissa I have ever met freaks out if: you water too much, too little, change lighting, change humidity, talk too loudly, look at it too much, don't look at it, touch it, don't touch it.

 

[WNC Bonsai]

Mr. rockm, sir,
Thanks again for your response. You're bang-on regarding hucking-around with the plant to get it to thrive inside. Serissa is that first plant, I've not been able to grow/thrive inside. Likely whatever the "hidden factor" is that makes serissa thrive/die (temperature cycling?) is not possible or economical for amateurs to recreate indoors.
Regarding the first serissa, had been keeping the plant indoor thinking that figuring out care and infrastructure might take some time. When the plant got weak, took it back to the nursery for 6 week rehab which worked the first time, but not the 2nd time. Pretty sure the tree was alive yet weak when it returned to the nursery the 2nd time. Have spent way too much time hucking around with the plants. The perfect trap engineers - an insolvable problem.
Regarding "overcare" as a root cause for killing Serissa, I would suggest that lack of clear/complete/detailed care instructions is likely at the top of the list.
Kindest Regards.

I suggest you watch some of Nigel Saunders’ YouTube videos on growing serissa. He has a very nice one that he has documented over the years, here is a link to his playlist of 64 videos.

African style, Serissa Progression

I'm pruning my Serissa japonica (Formerly Serrisa foetida) to resemble an African Acacia tree. The style is inspired by nature and is often called the Pierne...

youtube.com

 

[darzuo]

Mr. darzuo, sir,
Thanks again for your time and attention in this matter.
Grow light is QvvCev mdl 200SMD-P`30-XJ - 8W full spectrum https://latinafy.com/products/qvvce...bulbs-e27-base-8w-full-spectrum-yellow-light/
Don't recall seeing fans aimed at trees at APG, see photo above.
Light meter indicates about 5000 lux on tree at grow light and 1500 lux (cloudy day) at location chosen (some sun, mostly shady, for now) for outdoor living. Next time I'm in the area of Asia Pacific Gardening, will take light meter readings in their shade house. Using my eye-crometer, light intensity at APG environment is somewhat low, but will see what light meter says.
Not arguing, but I suspect (based on what I've found so far) the "missing factor" killing or thriving serissas may be a combination of temperature cycling, light intensity cycling, air movement and humidity (or lack of). My Spidy Sense is telling me serissa need a good chill at night, good to intense light and high humidity but not ruling out anything.
Sometimes, whining long enough about something can lead to a solution, please forgive my persistence.
Thanks again for your time and attention.

I don't have the expertise to comment on light intensity, I'm sure someone else would be able to. With regards to circulation, from what I've seen with high-humidity tropical nurseries, they usually have some large industrial fans providing circulation throughout the greenhouse just to prevent stagnation, not fans directed at trees. You can't necessarily feel the wind or anything, but I figure they must be there for a reason. Anyways, some plants are able to adapt to be fine as houseplants, and others (including most trees) aren't.

 

[Seattle Bonsai Newb]

I don't know why I'm chiming in here. Ha! But it's important to introduce plants back outside gradually. I've even scorched a yucca. I'm not a scientist but I think a plant indoors will be set up to absorb as much light possible where as ones outside will want protection from the sun. I put mine in the shade or with a table cloth over them to climatize.

Yep, found a shady spot for it. Will gradually allow more light as it get accustomed.

 

[Seattle Bonsai Newb]

every serissa I have ever met freaks out if: you water too much, too little, change lighting, change humidity, talk too loudly, look at it too much, don't look at it, touch it, don't touch it.

My view now too, yet I sense there's a "hidden care factor" that controls die/thrive of serissas, juuuust beyond the grasp.

 

[rockm]

My view now too, yet I sense there's a "hidden care factor" that controls die/thrive of serissas, juuuust beyond the grasp.

Nope. There is no single secret illusive silver bullet that this species “wants.” It is native to wet but well drained meadows in Southeast Asia India to Japan. There’s more than one variety. It prefers sunny warm locations.
When those parameters aren’t met it drops leaves and sulks. Inside is the opposite of all of the above

The example I posted from the National Bonsai Museum is as temperamental as any bonsai shop or Home Depot Serissa. When moved out of its greenhouse conservatory in the spring into direct sun it drops most of its leaves and sits for a few weeks. Then it pushes new leaves and grows all summer like a weed. That behavior hasn’t won it many followers among it caretakers. It’s a diva for lack of a better term

 

[rusticana]

Indoor accommodations can work, but not for any real extended time (like a couple of years--maybe longer, maybe much less). You simply can't replicate outdoor conditions indoors no matter how much money and effort you throw at trying to. When i started out, I used to have many "indoor" species, ficus, serissa, Australian brush cherry, schefflera. A lot of endless tail chasing trying to "cure" them of the inevitable disease and decline by insisting on keeping them indoors all year. I ditched most of them for "outdoor" trees after it just wore me out and I got tired of the cycle of healthy tree turning to a dead stick in a few months. I turned the corner on using temperate zone species after I simply plunked an ailing ficus from inside into direct summer sun outside on my southern facing deck and left it alone. It took a couple of weeks to adjust, but after that it took off like a weed, sending out five foot long shoots of leaves that had to pruned back three times before autumn arrived and I brought it back inside for the winter. It limped along and didn't grow until I put back outside in late April...

In the time you take keeping your tree inside, you tree will decline, getting weaker, dropping leaves etc.. You're already seeing evidence of that decline, you're just not recognizing it. Indoor conditions are controllable but those controls generally center around people not plants. Two humidifiers are great Eight or nine in an enclosed room would be better. Two humidifiers that keep a constant home wide or even room wide consistent humidity of 70 percent would mean mold, fungus and wet walls in the house. Grow lights do help, but unless you're using commercial grade high intensity lighting like those used in indoor agriculture set ups--for the Devils' lettuce primarily --your plant is still getting mostly inadequate light.

The bottom line in all this is that you're complicating things cost and experience wise by insisting on keeping the tree indoors when growing conditions outside offer a mostly cost-free and hassle-free and more effective option for the tree. FWIW, serissa (which is also called Japanese boxthorn) is a relatively newer species being used for bonsai. It is mostly confined to mass produced mass market sellers as its flowers "sell" the tree easily. It is, however, one of the more difficult species to keep. Keeping it indoors when it could be outside gaining strength to make it through winter indoors under artificial lighting and central heating adds to that difficulty. FWIW, the serissa forest at the National Arboretum and Penjing Museum is outside in mostly full sun all summer. It grows extremely vigorously outside here in the DC area. I've trimmed it back at least once in June after it pushed two foot extension growth. A stock photo of that Japanese boxthorn (serissa) forest is below.

I seem to remember back when first posted you said this was your second serissa. What happened to the first one?

Whatever the story, most new owners kill their first tree (s) because of overcare and misunderstanding. To be frank, I Wouldn't get too attached to the serissa. If you want a bonsai candidate that will stand up more inside, look at ficus.

View attachment 612575

Great summary. That is a super cool serissa forest. The little weeds are an added touch. I've been keeping trees inside over winter for many years. Serissa, pomegranate, podocarpus and montezuma cypress. They start getting sparse and desperate to get back outside. Not the montezuma and podocarpus ones they continue to put on good growth. I have no special lighting. Just south facing windows and a long LED over a bench allong a window in the basement with other house plants. No humidifiers. I believe the key to my sucsess is I keep my thermostat low. At the moment I have zero plants in the house just some cacti in the bathrooms. You have to be careful when you bring them in that they dont have bugs.