One other factor that will improve lawn growth is to apply lime every other year. Our soils and water are acidic and lime will reduce that acidity. It also makes iron in the soil more available for root uptake. Iron makes grass a darker green color.
The best way to irrigate a lawn is to water long enough to reach the full 6-inch depth of the root system and then let it dry for two or three days before irrigating again. Brief daily irrigation encourages short root depth and keeps the top of the soil moist, excellent conditions for weed seed germination.
Allen Wilson is a Vancouver gardening specialist. email@example.com