My lovely khat plant has once again outgrown its pot. Its about half a meter high with perhaps 40 branches from regular pruning. I recently moved to an area in a different climate zone with temps between -2c to almost 50c so the plant has to remain in a pot as i dont think it will like the colder temps and may have to be moved inside during the coldest parts of winter.
A pot about 1meter high with a diameter of 1meter or so will be used. What types of soil mixture should be used ? I have a fair amount of experience with this but my plant doesnt grow as fast as i believe is possible. Suggestions ?

In it's native habitat it grows into a small tree, but you're not likely to get there in a pot or in an environment with freezing temperatures. The only specifics I recall on this one as far as soil goes is that, as with many arid region plants, you should have well drained soil, and I've long ago read that crushed volcanic soil (available from hydroponics/grow shops in the US as a soil medium mineral additive) will provide minerals that will help with the alkaloid production. No idea if the volcanic soil additive makes any difference, but a small bag doesn't cost much and it just makes sense to have a well drained soil.

Still waiting to hear if anyone's had experience combining a khat quid with the resinous/basic preparations that taste somewhat of anise used for coca chewing in the Andes ... I suspect that could have some efficacy in alkaloid absorption from a quid.