The rice plant usually takes 3-6 months from germination to maturity, depending on the variety and the environment.
Agronomically the growth cycle can be divided into 3 growth stages: vegetative, reproductive, and ripening.
Vegetative stage: tillering, gradual increase in plant height and leaf emergence. Start of tillering: ca. when the 5th or 6th leaf develops.
Direct-seeded rice normally starts tillering earlier than transplanted rice (no damage during transplanting).
Differences in growth duration are primarily due to differences in the length of the vegetative growth stage. (e.g. early maturing varieties have short vegetative stages).
Heading = synonym for anthesis = usually defined as the time when 50% of the panicles have exserted. It takes 10-14 days for a crop to complete heading because there is a variation in panicle exsertion within tillers of the same plant and between plants in the same field.