This is a complex question with lots of variables but we will address this in a simple way. We recommend a spring time application of pre-emergent weed killer during the month of February. We also recommend a fall application of pre-emergent during the month of October. The months in between, we recommend a fertilizer every 8 weeks. A great, versatile fertilizer is 15-5-10 ratio for all purpose lawn needs. Contact us with more in depth questions or guidance.