What's Taking So Long

Sluggish recovery from greens aeration and a general poor appearance in the zoysia this year is worth a little research to see just how different things are compared to last year.  Memories can fade, but we keep great records and can easily go back and check the data.  That doesn't make any of us feel better about the reality of what's happening now, but it hopefully sets the record straight.  

The grass doesn't know what day it is, but it knows how much useable warmth it's received.  We measure that using Growing Degree Day models.   This year, in the 25 days since aeration we've accumulated 303 growing degree days.  Last year in the same time following the same aeration procedure we accumulated 443 growing degree days.  That's a big difference and it shows in the condition of the turf.  We need warmer weather to aid in turf growth.  

Perhaps more critical than the temperature struggles is the moisture stress.  Last year we received 3.3" of rain in the 25 days following aeration.  This year we've received just .85" of rain in that time period.  Wind has also been a bigger factor this year meaning that the deficit is probably even more than the difference in the rain totals.  Evaporation has been greater as well.  

April 14 – May 9	2025	2026	Difference
Growing Degree Days (Base 50°F)	443	303	-32%
Rainfall	3.30"	0.85"	-74%

Weekly Precip April 9 - May 9      2025 vs. 2026

In short....this year has been BAD.  Last year was just OK.  

If I could have my way I would wait to aerate until early May.  This would greatly increase our odds of having adequate growing degree days for turf growth and recovery.  As it is, we have one shot to get the much needed work done.  Outings are a big hurdle to our flexibility, so hopefully we can move some around for next year to free up a date that would almost certainly result in a faster recovery.  Another big issue that doesn't get much attention is that we have been aerating the day after the Fredericksburg Amatuer each year.  The things we do to make the greens as good as they can be for that event are the opposite of the things we would do to prep for aeration.  Aeration is like surgery and you need to be in good shape to go through it.  We beat the greens up, dry them down as best as the weather will let us, try to keep the growth rate low, etc...all to get the best speed and firmest surface possible for the event.  In reality, we should wait at least a week following this event before aerating.  We wouldn't finish a marathon and go right to the operating room.  The greens putted fantastic for the event, but they were not ready for what we did to them the next morning.   Especially in the absence of adequate warmth and rainfall in the weeks that followed.  If we continue to host the Fred Am and keep it in it's time slot, we should shuffle the outing schedule to allow us to aerate greens in early May.