l would like to grow some calceolarias in my greenhouse, when is the best time to sow the seed?

They should flower early in the following year.

They do not like hot conditions, max. 18°C(65°F) so delay sowing if the weather is very hot.

Once germinated, grow the plants in cool conditions and out of direct sunlight. 

They should bloom within 18-20 weeks after sowing.