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Keeping Turf Green in a Northeast Blizzard

By Tony Leonard, Groundskeeper, Lincoln Financial Field

A groundskeeping crew rolls up a tarp after scraping snow from Philadelphia's Lincoln Financial Field in preparation for January's NFC Championship game. It took weeks of work to guarantee green for the midwinter game.

Tarping the 2002 NFL Championship Game

It's Jan. 15 and folks are buckling down for a stretch of bad weather. Snow, sleet and freezing rain are forecast. Road crews are gearing up the plows, salt spreaders and coffee to get ready for upcoming events. But not at Lincoln Financial Field, home of the Philadelphia Eagles. We are the grounds crew, and we've got the added burden of a NFC Championship with the Eagles and the Carolina Panthers to worry about.

The Pre Season Huddle

Our preparation for the big game started in a meeting room a few years ago. We know that in Philadelphia we are prone to winter storms from November through March. To grow natural grass in this climate, we need to have every tool at our disposal to provide a safe playing surface at all times–regardless of weather.

Covermaster Raincover Lite tarps measuring 250' x 80' are used to protect the field from snow and ice. The front-loader with plastic tube at lower center is used to push snow off tarp–the tarp sections are then rolled on the tubes and stowed in a unique storage area under the first and second rows.

Millennium Sports Technologies led by Dan Almond aided in the design of the new field. Dan and I selected a blend of Kentucky Bluegrass that is best suited for the weather and shade conditions of Lincoln Financial Field. Once we made that decision, the root zone, irrigation, drainage, and overall crown of the field fell right into place.

Another system that we installed is called Grassmaster. The system is a matrix of plastic fibers that are sewn into the field to stabilize the root zone when the grass wears thin and roots are no longer able to support proper footing. The Denver Broncos were the first NFL team to utilize the system, and their field is still playing as strong as ever. The fiber foundation helps provide the footing that is needed late in the season to prevent divots and blow-outs.

Rows of plastic tubing circulate a glycol-water solution that gently warms turf in the Philadelphia stadium. The system keeps root temperature in the 60s, permitting growth and even germination in midwinter.

Additionally, to compensate for the weather we needed a sub-surface heating system. Most stadiums in the northeast have these systems installed in the field. With the new wave of stadiums, the heating medium has moved from electric coils to hydronic, or water-based, systems. They consist of boilers, plastic tubing, valves, and plenty of glycol-water solution. After reviewing the stadium's sun-shade patterns, I thought it would be best to heat the field from 6 different zones. Each zone would start from the back of the end zone and run out to the 50-yard line. Each half of the field would have three zones. The planners then designed the system to heat the field up to 70 degrees F four inches below the surface. To do this, they needed 28 miles of pipe and two boilers that generate 6 million BTUs. This would be the life-support system for the turf from late November through February. This kind of system is essential for keeping grass green and allowing germination and growth in the dead of winter. (It is not designed to melt snow, but does accelerate the process.)

Preparing for Winter's Onslaught

Heading into the frigid months of December and January we make sure the grass is as healthy as it can be before it endures the final stretch of games--which include at least three NFL games as well as the historic Army-Navy classic. To accomplish this, our crew is continually throwing seed mixture on the field's wear areas. The rate can vary from seven to 10 lbs. per 1,000 square feet of perennial ryegrass and from five to eight lbs. per 1,000 square feet of annual ryegrass. For the latter task we chose Panterra Annual Ryegrass from the Barenbrug Seed Company. It is an annual ryegrass that's used for overseeding of bermudagrass fields during winter months in the south.

The Philadelphia stadium's heat-tubing system was installed 11 inches under the surface in October, 2002. Visible at left are dozens of butterfly valves that let groundskeepers turn off individual lines if leaks occur. Black cylinders to valves' right (looking like flower pots) cover points where the system is filled with glycol solution.

Our goal in this time-sensitive situation was to find the fastest way to establish grass within a week. Annual ryegrass can do the job in four to seven days. Perennial ryegrass takes seven to 10 days. The process can be accelerated by pregermination.

After each game our crew will walk the field and sprinkle a "cocktail" of products including sand, calcined clay and grass seed over the field's worn areas. We are careful to prepare this "divot mix" a week before the game to give the seed-germination process a head start.

Field ready for NFL Playoff Game

Our fertilizer needs to be at appropriate levels to guarantee lush growth. We like to keep the potassium levels up, which makes the grass more resistant to weather stress and wear and tear. During the football season, we apply potassium at one pound per 1,000 square feet per month. This gives the plant adequate nutrient in the sand-based soil. For nitrogen, a dark, organic-based fertilizer will push some growth and keep the plant green--even late in the growing season.

Our most reliable and inexpensive tools are growth blankets. We use Evergreen Covers, which accelerate the growth of grass quickly. Even without the heat system, this can retain enough warmth to establish grass in a couple of weeks.

The field is now ready for the Jan. 18th showdown between the Philadelphia Eagles and Carolina Panthers.

Note stadium shadow in background–shade is a factor taken into consideration when choosing a proper turfgrass blend. (For the record, the Eagles lost the game (14 to 3.)

Since we are fortunate enough to have the heat system, we can combine both tools to grow grass effectively in the winter. Our field temperatures at 4" below the soil range between 62 and 68 degrees (F). Keeping the field at these temperatures and using the growth blankets (with a dose of sunshine) can make for a green field in seven days. The growth blankets are a great investment for anyone having to grow grass in the winter or get seed established in the early spring.

In the event of snow, we cover the field with a set of rain tarps. Snow is plowed off the tarp on to a track surrounding the field–it is then hauled out of the stadium. To haul the snow out, we attach a pipe to the tractor's sharp-edged bucket. We use this setup to push the snow off the tarp to the track and then out of the stadium.

Other crews use (golf) bunker rakes, PVC pipes attached to plows, or other creative ways to move snow off tarps. We have found that this is destructive to the grass, but it is a necessary task. A supply of calcined clay, such as Turface, is used for wet areas on the edge of the field where the media gather before a game. This product makes it easy to soak up excess moisture and firm up soft areas.

With the creative use of a heat system, growth blankets, well-fertilized grass, tractors, plows and water-absorbant clay, a dedicated crew can be prepared for whatever Mother Nature sends its way.

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November 22, 2019, 1:38 pm PDT

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