Tell us more....
What are the growing conditions? Is the plant experiencing cold weather? Is this a nutrient deficiency? Is the potting mix staying too moist?

The form of the plant looks nice overall.

Josh

- I keep it outside all seasons, so it is experiencing cold and hot weathers.
- I don't over water it just when the soil is almost dry
- it get about 2 hours of full sun
And again this is the first time it do that although I didn't change anything in raising it for the past 5 years

Hmmm, well hopefully some other folks will pop in and explore this change in leaf color. I would attribute it to colder weather...which I think I've seen occur on mine at the beginning and end of the season (when I have mine outdoors). I assume you're in a warmer zone, but how cold overnight has it been?

Josh

yeah I live in lebanon and we had a rough hot summer
in winter its about 5-10 ðc at night. But I don't think it's the weather, it started this after spring

In that case, do you fertilize?

Josh

no never! but if that was the problem, why now? after 5 years?

In a pot ? last time repotted ? root bound ? Also many plants dispose of waste by the roots as well, leaving a chance the soil is contaminated from it's own waste as well

"the soil is contaminated from it's [sic] own waste as well"

Don't think I'd buy this comment.

Been on here 12+ yrs, never heard it before & if true, plants would be poisoning themselves anywhere there weren't humans around to re-fresh their mix. Think about it.

Can you pls. offer any back up or proof to support such a statement?

Well, now could be when the deficiency is finally showing up, Nour ;-)
I would give it a 1/8th strength dose of fertilizer. And if you haven't re-potted in a couple years, next Summer would be the perfect time for it. A pic of the whole plant in its pot would give us an idea if it's becoming root-bound.

Karen, perhaps Nomen meant that salts are building up in the potting mix? Not sure about that comment. Needs clarification.

Josh

Good point as well both. A result of higher salts soil can be the result of the biproduct root waste as well.

I do know I've read the roots can send waste back into soil somewhere over time and am still looking for the more relaible than me sorce of info where I had read it.
I may find that the waste is an indirect or direct result of higher salinity in soils.

As stated by the original poster of five (+/-)) I think it would be would be a good idea to repot in a feash new soil or mix. My prefferance would be for a good draining mix as it flushes the mentioned salts ( or waste) easily with watering.

Even though it is putting alot of stress to the plant I am an advocate of sooner is better than later for repotting but the plant would also would need a reconditioning or recovery time before going back outside or into full sun.

aha that makes sense! I did change the pot but didn't add alot of soil cuz the new pot wasn't too big
well thanks all, u were helpful ^-^