Traditional grammar pedagogy conceptualizing grammar as rules of thumb fails to provide learners with comprehensive, accurate, or systematic knowledge on the system. The present classroom-based study aims at investigating application of an alternative pedagogical grammar method integrating the pedagogical framework of systemic theoretical instruction and the linguistic framework of cognitive grammar to instruction on the English tense system. Four instructional sessions were conducted in an English language classroom in a Hong Kong secondary school, and impacts of the pedagogy on students' grammatical production were examined by means of tests and focus group interviews. The pedagogical approach was discovered to exert limited impacts on students' controlled and free grammatical production statistically, yet the effect size of the pedagogy on students' grammatical production was large. Several factors ought to be taken into consideration in application of the pedagogy to second language grammar instruction.