All turfgrass managers use inputs to help regulate turfgrass
growth rate. Slow growing turf has limited traffic tolerance, is more
susceptible to disease, and can have an unattractive lime green color. Fast
growing turf can also be problematic with succulent leaves, higher nutrient and
sugar demands, different diseases, increased mowing requirements, accelerated
thatch production, and poor surface playability. An “ideal” growth rate would
provide recovery from traffic, sustain acceptable visual quality (color,
density, etc.), and minimize mowing requirements. Nitrogen fertilizer, irrigation,
plant growth regulators and even mowing practices are all tools to help
turfgrass managers manipulate growth rate.
I’m encouraging turfgrass managers to establish growth rate
goals at their sites. Then use management practices to achieve those goals. Many
golf course superintendents have started to collect clipping volume from one or
more greens to assess growth rate. In a recent Twitter poll/thread, many of
these superintendents started 1.0 to 1.3 quarts of clippings from 1000 ft2 of
greens – equivalent to liters per 100 m2 – provided adequate recuperative
potential and playability on their greens. Clipping volumes less than 1.0 could
not handle traffic and had problems with moss and algae and volumes greater
than 1.5 had reduced green speed. We also found yield goals can be helpful for
lawn height turf. Tall fescue that was growing less than 1.5 inches per week
had more disease and discolored leaves.
Faster growing lawns needed to be mowed more frequently, but
didn’t look healthier than lawn plots growing at 1.5 inches per week. To
observe the 1/3 rule, lawns maintained at 3.0, 2.0, or 1.5 inches would need to
be mowed every 7, 4 or 3 days, respectively if they are all growing at 1.5
inches per week (0.21 inches per day). A homeowner maintaining a tall fescue or
bluegrass lawn at 3 inches should not have an issue mowing on the weekends when
the turf is growing at the ideal rate.
The “ideal” growth rate at a specific facility does vary with factors including microenvironment, species and cultivar, management expectations, etc. For example, low-mow bluegrasses may never grow 1.5 inches in a week, so that goal would be inappropriate. The season will also have a big impact on growth rate. As the days get shorter and the temperatures cool this fall, expect the growth rates to slow down. This is normal and it means that growth rate goals will need to change from summer growth goals. The main point of this article is to encourage managers to develop growth rate goals and adjust management to achieve those goals during the growing season. This can be accomplished by formally collecting clipping volume, by counting the days between mowing events, or recording how many times the bucket/bag needed to be emptied when mowing. Write down the clipping yield and then manage it accordingly with nitrogen fertilizer, plant growth regulators, irrigation management, and mowing practices.
Bill Kreuser, Extension Turfgrass Specialist,