tops of blades browning
We've been renovating our small lawn since moving into our house a year and a half ago. We use a reel mower, and recently we've noticed that the tops of many of the grass blades are turning brown. This is not just the very tips of the blade, but maybe 1/3 to 1/2 of the blade. The bottom half looks totally fine. It affects the lawn uniformly, but I think it may affect the thinner/finer blades (fescues?) more.
Could this be the result of a dull mower blade? Our reel mower is an old hand-me-down and we do sharpen it by hand, but perhaps we need to have it professionally sharpened. My best guess is that maybe the fine blades bend over too much and get damaged rather than actually cut?
The details on the lawn:
Last spring we basically started from scratch in the back yard, raking up what little lawn was there, turning the soil, amending with compost, and seeding heavily. We overseeded in the spring as well, and have been very happy with the results. We have clay soil, and have used a granular organic lawn fertilizer (it has bone meal, kelp, etc.). We have an irrigation system and water deeply once or twice a week depending on weather. The lawn is in part shade, getting somewhere between 3-6 hours of sun depending on the section.
For seed we used Jonathan Green Sun & Shade mixture grass seed, which is described as: 20% Carmen Chewings Fescue, 20% Frontier Perennial Ryegrass, 20% Hood Chewings Fescue, 15% Darkstar II Perennial Ryegrass, 15% Deepblue Kentucky Bluegrass, 15% Eugene Creeping Red Fescue.