Tea Just Live in Tropical Climate
If we observe the tea producer is just come from tropical climate and just small sub-tropical country can cultivate tea. In sub-tropical with four season tea may can grow but when this country change their weather from one season to other season can problem on their tea plantation. Tea may can be planted in summer season but after through cold season, all the plantation will die, so this why tea is not planted in sub-tropical country with four seasons.
Tea cultivation in tropical country just in cold weather but with enough sun light. Tea plant need cold temperature about 18 oC to 23 oC but can't grow when the weather below that temperature like in Europe that can reach about 7 oC even reach below 0 oC. This condition make problem on tea cultivation needed.
You can find tea field in Asian country like in Indonesia, Malaysia, Thailand, Vietnam but just can have good growing in cold weather area or this area have high level from sea, says about 700 m or more from sea level.