There are two types of grasses, warm-season (Bermudas, Zoysias, St. Augustine) and cool-season (fescues, ryes, bentgrasses, bluegrasses). Many factors distinguish the various cultivars, both in the general sense and more specifically between species. While we will not get deep into the weeds (pun intended) while discussing grasses this morning, I think that a little background information might be valuable as the discussion turns more from grass type to lawn maintenance, to turf performance.
If you are reading this, then you most likely have a variety of fescue grass in your lawn. Fescue is a general name given to a species that has several cultivars. Differentiating between specific fescue cultivars and their genetic pairing with other grass types is not of critical importance for this discussion, so moving forward any reference to fescue should be taken in the general sense.
Fescue is a cool-season grass that is quite popular in the transition zone (this is the climatic zone that you live in). It establishes easily from seed in the cooler fall months, stays green year-round (usually – more on this later), and can tolerate a variety of growing conditions. Fescue is also a bunch-type grass. These are grasses that grow in bunches and do not have Rhizomes that spread laterally (think Bermuda grass). Being a bunch-type means that any injury to the turf must be reseeded to fully recover.
As mentioned above, Fescue can tolerate a variety of growing conditions. Fescue grasses generally preform best when temperatures are between 65-80 degrees for leaf growth and 68-86 degrees for seed germination. New root growth for most cool-season grasses occurs rapidly when soil temperatures are between 50-65 degrees at the 1-inch depth and will continue into the upper 80’s, albeit at a reduced rate. However, once temperatures in the soil reach 90 degrees or greater, root growth is greatly reduced, and care must be taken to protect the root system from damage.
Though Fescue can and does tolerate a wide variety of temperatures at which it can perform, it is susceptible to heat and drought stress. Fescue can tolerate the extreme summer heat that we routinely see here in the Carolinas, but it needs a break at night from those high temperatures to recover from the day’s stress and generate some new growth. Generally, Fescue requires cooler nights (< 70 degrees) to recover from high heat the previous day, if the night stays warm (> 70 degrees), then the plant cannot produce the energy that it needs to repair itself and grow the next day. Long stretches of high nighttime temperatures can be brutal on Fescue (many in the Carolinas are seeing the effects now from a brutal June weather pattern). Fescue can look devastated in the summer, and while high daytime heat is the first target of blame among many (and does share some responsibility in decline), high nighttime temperatures are more destructive, especially when coupled with high humidity.
With that information in mind, let’s examine the weather over the past month as it relates to historical averages for our area. June 2018 was on average, 5 degrees warmer than normal. Think about that for a minute….5 degrees! That is a noticeable variation and should not be taken lightly. During the month of June, we saw:
• Average High/Low: 87/65 degrees
• Actual High/Low: 91/70 degrees
• # days > average high: 26
• # days > average low: 28
• # days > 86 degrees: 27
• # days > 70 degrees (daily low): 15
• # days > 90 degrees: 19
• # days > 92 degrees: 13
• Total precipitation: 1.47″ (-3.25″)
• Average precipitation: 4.72″
As the numbers above indicate, June has been a brutal month with respect to traditional averages for the area. The result is that some folks are seeing decline in their Fescue sooner in the season than is typical. Usually we see this sort of weather begin to affect Fescue negatively in late July, this year it came a month early.
The big question we always get is what can I do to improve my lawn or what are you going to do to make it better? There is no easy answer for these queries. While there is a lot that can be done to mitigate the effects of extreme growing conditions (the last two weeks of June come to mind), there is little that we can do to counteract mother nature. Reversing course once damage appears can be quite challenging during a Carolina summer. All hope is not lost though.
Fescue may turn brown/tan, but can often survive periods of drought by going into a state of semi-dormancy, and will struggle in hot/dry summers (have you been outside). During periods of extended hot/dry conditions, fescue will require significant water, in excess of 1″ per week. Many homeowners irrigate their lawns in some form or fashion, however unless you have a professionally installed irrigation system that is programmable and have had it calibrated to meet your watering requirements, there is not a practical way to get that much water on the lawn in a given week without some assistance from mother nature.
When we do irrigate our lawns, it should be to avoid wilting, but only to supplement natural rainfall, not to replace it (unless it just is not rainy, like the last month was). We should also be mindful of our irrigation timings. Early morning is the best time to irrigate our lawns (before sunrise is ideal 3-5 am). On established lawns, deep infrequent irrigation is key to strong deep roots. Deep and infrequent means water longer cycles with more days between waterings, wetting the soil to a depth of around 3″. On lawns that are not quite established (newly sodded or seeded), we want to water as needed. Since the root systems are not as strong in a newer lawn, we want to water more frequently to nurse the grass through the days until we get a break in the weather.
If you have questions about your irrigation practices, let us know and we can help you develop a plan.
Fertilizer this time of year is NOT THE ANSWER. When temperatures are like they have been lately, turfgrass root systems are limited in their uptake ability and there is no need to stimulate a stressed plant that does not want to grow under adverse climatic conditions. If fertilizer is applied to a fescue lawn now, you will accelerate its decline. Patience here will pay dividends later.
Fescue may be allowed to go dormant (a natural process that is used as a defense mechanism by the plant) if heat and drought set in, and you will be surprised at the recovery once there is relief from the stressor, even if the grass was completely tan.
The best course of action right now for those with stressed Fescue is to trust your turf professional, consult one if you haven’t, and be patient (I know that is not what you want to hear), things will improve but it will take some time and cooler weather.
The weather will break, and recovery will happen. It only takes a few cooler nights to notice a significant improvement in turf quality, so hang in there for the time being.