Yellowing leaves on Serissa variegata

[Kalmia]

Hi everyone. This is my first bonsai serissa and I read that yellowing leaves could be a sign of overwatering, but I only watered it last week. I keep it indoors by south facing window, I live in Italy zone 8a so outdoors are still around 16⁰c daytime and my house temperature is maintained at 18.5⁰c, 19⁰c max. Soil is akadama with some perlites.

Could it be too much sun? The sunset is at 5pm and I give additional lighting until 10.30pm using full spectrum grow light. So basically it receives light from 8am to 10pm daily.

Please advise. Thank you.

 

[pandacular]

I keep it indoors by south facing window

It's almost certainly this. Move it to an outdoor location.

 

[Kalmia]

It's almost certainly this. Move it to an outdoor location.

Thanks. So I should bring it back indoors when the sun is down?

 

[pandacular]

Given your climate and the brief readings I've just had on this plant, I don't think that is necessary.

Also, welcome to the forum! There is much to be learned here.

 

[Kalmia]

Given your climate and the brief readings I've just had on this plant, I don't think that is necessary.

Also, welcome to the forum! There is much to be learned here.

Are you sure? It's 3⁰c outside at night.