Ask the Superintendent – The Longest Day

Welcome, avid golfers, to some of the longest daylight days of the year! June is a great month for getting in at least 36 holes per day. Thus, the question that I get most often this time of year is when is the longest daylight day of the year? Most golfers are aware that this mystical and scientific day is in June, but many golfers can’t quite remember exactly when. 

I believe that, after nearly 40 years in the golf turf business, I have deduced correctly that the reason for this oft-asked question is so people can play as much golf as physically possible on the day in question, which makes sense. If you tee off close to first light as the first official tee time and continue to replay until the sun sets and suspends play on the longest daylight (sunrise to sunset), you should be able to play more golf on that day than any other day of the year, weather permitting. There is some rather lengthy science connected to the solstice, or longest daylight day of the year, not to mention early historic sites such as Stonehenge. Let’s look a little deeper at what the Earth and sun are actually doing to give us those extra golf holes. 

Solstice Facts

The summer solstice, or estival solstice, occurs when one of Earth’s poles has its maximum tilt toward the sun. It happens twice yearly, once in each hemisphere. For that hemisphere, the summer solstice is the day with the longest period of daylight and shortest night of the year, when the sun is at its highest position in the sky. At either pole there is continuous daylight at the time of its summer solstice. 

For us in the Northern Hemisphere, this year’s summer solstice is June 20, also known as the longest daylight day of the year. The opposite event is the winter solstice, also known as the shortest daylight day of the year. Avid golfers know that while the winter solstice is a sad day, it does start the countdown of days getting longer headed for the summer solstice. You may ask the obvious next question: why is the solstice not on the same day every year? The answer is that the Earth’s elliptical orbit around the sun requires for some adjustment to account for the actual travel time around the sun, so the summer solstice could fall on June 20, 21 or 22, and if you are counting every minute of daylight, then details matter. Thanks for sticking with me and remember that the summer solstice is June 20 this year and plan your tee times accordingly. 

Now let’s look a little deeper into the summer sun, its impact on plants and our ability to grow them. 

Summer Sun Angle

Playing more golf is a great advantage for the long June days, but for the avid gardeners and agronomists among us, there are a few more things to be aware of. First, the summer solstice is the official first day of summer and the sun is at its highest angle of the year. That means that areas of your lawn and landscape that were in the shade are now getting the most sun of the year, and that means they will require more attention. Plants will use more water this time of year with evapotranspiration increasing, but it is also true that areas of your lawn and garden that once were shaded will find themselves taking a heavier dose of sunlight over the next few months. This increase of activity in the plant will require more water. Adjusting your watering to address these use requirements will keep your lawn and landscape looking good. Do not forget to add a bit more fertility, as well; organic fertilizers that help build soil structure with low burn potential work best. 

This may also be the time where some late-season plantings from last year may struggle, as they face more direct sunlight than they have been used to. Shade cast is the term we use to refer to anything casting a shadow, and shade cast shortens in the summer and lengthens in the winter. Shade cast is also what makes a sundial work. Did you just see an image of a sundial in a garden? Now you understand the seasonality. This is why north-facing slopes struggle to support plants, as they often fail to produce enough sunlight year-round and face lower winter temperatures as well. This is why we adjust watering and fertility to be optimum as the seasons and sun angle change. You can mark shade lines and sun exposure with pictures, flags or turf paint to help you monitor the changes in your lawn and garden. 

Professional Tip

When it comes to sun, shade or light tracking, I always use the Sunseeker app. It’s the best $9.99 you can spend on the subject. Sunseeker is a comprehensive solar tracking and compass app. It shows the sun’s hourly direction intervals, its equinox, winter and summer solstice paths, sunrise/sunset times, twilight times, sun shadow, the golden hour and more. The app allows you to add sun-event notifications and has a widget showing the day’s solar data and position on an arc. The surveyor view shows the solar direction for each sunlight hour. Sunseeker has both a flat compass view and a 3D Augmented Reality (AR) view to show the solar position and path. It is impressive and I usually do not recommend any specific products, but this one is that good. Sunseeker, by definition, is a sun locator which uses GPS, magnetometer and gyroscope to find the correct solar position and sun path for your current location. It’s easy and fun to use. 

Here are a few extra ways to use Sunseeker and think about how the sun angle impacts our lives: 

▶ Photographers: to plan according to the golden hour or blue hour and optimal sunlight conditions, sunrise and sunset times and directions.

▶ Cinematographers: this sun tracker and sun surveyor enables you to find the sun exposure, directions, sun shadow and sunrise/sunset times for any location.

▶ Real Estate Buyers: can use the app before buying a property to check the sun path and to find the sun exposure of properties.

▶ Drivers: Sunseeker lets you track the sun path and movement during the days and helps drivers know the sun position to find how long the car will remain in the shade at any given parking spot.

▶ Campers and Picnickers: for anyone planning a day out, the Sunseeker app will help in finding where to camp, sit or pitch an umbrella, depending on the sunlight and sun direction.

▶ Gardeners and Golfers: Sunseeker can also help with finding optimal planting locations and seasonal sunlight hours as a sun rise calendar and plan extended golfing hours.

▶ Architects and Surveyors: for visualizing the spatial variability of the solar angle throughout the year and using the compass app as a sun surveyor and calendar to determine the sunlight directions.

Conclusions

We who spend our working and recreational lives outdoors are connected to the rise and fall of the seasons. Being able to predict the daylength and other factors allows us to maximize our fun and business opportunities. 

Now that you know the story behind the longest daylight day of the year, I hope that you will play lots of golf. See you next month when we really turn up the heat!