We are finally getting near the end of the spring growth flush for our major cool-season lawngrass species like Kentucky bluegrass, ryegrass and tall fescue. With a little help from mother-nature, hopefully mowing will be more manageable from here on out. During the past few weeks you may have noticed a decline in overall appearance following mowing. This could be due to several reasons, first if your lawn is moderately well fertilized and you are only able to mow once a week the abundant foliar growth may have meant you are probably cutting more than 1/3 of the leaf canopy during each mowing. This may have caused a scalped appearance. Furthermore, the abundance of leaves and thick turf makes getting a quality cut difficult. You may occasionally notice a bogging sound with the engine when mowing thick, damp turf. It is hard for mowers to cut thick turf cleanly.
Other factors contributing to poor mowing quality are turfgrass species and seedhead production. The common turf species like ryegrass and tall fescue have very tough leaf blades which confer good wear tolerance but make them difficult to cut cleanly. Cool-season turfgrasses produce seedheads during the spring months, these inflorescences are packed full of lignin which is a specialized tissue that is also difficult to mow cleanly. The sum total of tough leaf blades, seedstalks and dense turf has worn mowing equipment or dulled mower blades.
In summary, if the appearance of your lawn after mowing is not what you expect there are a few things worth evaluating. First, check your mowing height and mow as high as possible for the species being managed (2 ½ to 3 inches is a healthy height for most lawn grasses). Second, consider your mowing frequency, a higher mowed turf will need to be mowed less frequently and scalp less often than a closely mowed turf. Lastly, and probably most importantly, check your mower blades a few times throughout the season. Dull or damaged mower blades do not cut cleanly and leave ragged leaf tips (see photo), this is evident by the whitish cast when viewed looking across the turf canopy from a distance (see photo). These ragged wounds are very stressful to the turf plant, and provide an excellent opportunity for some disease pathogens to penetrate and infect the plant. Remember, mow it high, let it lie, try not to remove more than 1/3 of the leaf blade during each cutting, use sharp, clean mower blades and you will have a happy, healthy lawn!
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