Tea feels very weak to me, especially compared to some of the other plantation resources. Tea on a grassland tile gives 2 food and 1 production, while silk on forest, grassland gives 2 food 1 production and 2 gold. After getting a plantation, tea is 3 food 2 production, which is the same as you'd get from a cattle tile with a pasture.
I'd probably add a point of food or culture to tea.
I'd probably add a point of food or culture to tea.