It lays outside, quietly hoping you’ll notice its hunger. Rich, brilliant tones have settled to dull green, with a golden glaze coating the swath. Sure, you still have to mow it every week, but the season of growth has left your lawn in need of a boost from fertilizer.
September is the month for fall lawn care, and the most important aspect to lawn rejuvenation is a strong fall feeding. Use a turf-builder fertilizer that has both quick and slow release nutrients. All-purpose mixes have 16 nutrients needed by turf to be healthy – a balanced fertilizer goes beyond offering nitrogen, phosphate and potassium oxide (the N-P-K numbers).
Lawns aren’t supposed to turn color in the fall, so if yours is taking on a yellow pall, you need to add some iron. But our soils are so alkaline that you need chelated iron to apply to lawns that suffer from iron chlorosis. Be aware that not all chelation formulas work in our soils, so look for ethylene diamine dihdroxyphenyl acetate (EDDHA). The more commonly, and cheaply, available EDTA (ethylene diamine tetraacetate) is only active in pH-neutral soils – something we rarely see here in Colorado.
Nitrogen depends on temperature and moisture for release into the soil. When we have warm days plus a few rain showers, lawns get a quick boost of food, and under ideal conditions, turf – an active scavenger of nitrogen – will take up the nitrogen within hours of it being put down.
This is perfect for lawns towards the end of September, because the quickly available fertilizer will increase turf vigor, and the slow release will continue encouraging turf rebuilding well into fall.
Thin areas where the grass has died off completely can be over-seeded now. To get the best results from over-seeding, water the lawn 24 hours before aerating. Pass the aerator over the turf in two to three directions to open up many holes. Immediately over-seed with the grass of your choice, but in general, tall fescues do not blend well with bluegrass, perennial rye or fine fescue because of its wide grass blades.
Grass seed takes a while to germinate, so keep humidity on the lawn for 14 to 21 days.
Use starter fertilizer at the time of overseeding to feed the turf without burning the new shoots.