Getting back-to-front green slope right

A common golfers’ complaint is that “the green didn’t hold.” Architects put a lot of thought into making them hold, but don’t always get them right. In most cases, we try, because golf is hard enough, and for average golfers, an airborne shot that hits the green surface is a good shot, and they feel it ought to stay there.

Most golfers would be surprised to learn that architects want to help their game, and that 90 percent of green contours are designed to accomplish two basic things. It’s very common practice to design greens that:

1. Are higher in back than front, sloping towards golfers to make them visible, and assist in holding their shots on the green.
2. Have two distinct drainage swales to minimize any drainage concentrations that could cause wet spots and turf damage to the green surrounds.

There are exceptions to the two swale “rule” of course. Small greens can usually drain one way and large greens, especially those with three distinct tiers should have three drainage swales off the green, so upper tiers don’t drain onto lower ones. However, on mid-size greens, three swales often create a “crown” near the middle of the green that rejects shots in a very player unfriendly manner. On mid-size greens, third swales should drain only 5-10 percent of the green.

In the old days, many long holes had flatter greens for the anticipated long iron running approach, while short ones would be steeper to help “check” a short iron. Now, we tend to design proportionally steeper slope for lower flying, longer approach shots. Having measured shots and slopes, it appears that the minimum upslope required to stop shots is 1.33 percent, and 1.5 percent is the minimum for drainage. As a guide, I figure it takes an overall slope of 0.1 percent per likely approach yardage, i.e., 1.5 percent for 150 yards or less, 1.75 percent for 175 yards, and 2 percent for 200 yards or more as a “rule of thumb.” This is often adjusted upwards on uphill and downwind shots, where spin is reduced, and occasionally reduced on downhill or headwind shots, where backspin naturally increases.

Designing two simple drainage swales sounds easy enough, right? Well, not always. As with any design component, getting the details right spells the difference between practical and beautiful and unsatisfactory in play and look.

One drainage swale usually exits the green front and the second drains the back portion of the green to the natural low side. The front swale, aimed at golfers, naturally handles both basic criteria. That swale is often also gently concave to help hold shots drifting off line, while shedding drainage away from green side bunkers. The front drainage swale should slope towards golfers:

• As gently as possible, near the 1.5 percent minimum required for drainage, since:
  • Most shots land (and ball marks occur) in the green’s front third to half.
  • Flatter slopes reduce ball mark damage.
Putts from above the hole are less likely to be “de-greened.” On tiered greens, some architects even put a small ridge in front of the green to help “hold” severe downhill putts.
• Carrying less than 50 percent of the green, since:
  • Many mowers turn around in the approach,
  • Many sets of sprinklers often overwater it, and
  • Most golfers walk through it.

Greens are usually better aesthetically when green drainage areas are asymmetrical, divided 60–40 percent, 60–30–10 percent, 50–40–10 percent, etc. In some situations, more drainage should be directed off the front of the green when:

• Hole is uphill, promoting better visibility if the swale aims right at golfers.
• Backing mounds shed large flows on the back of the green,
• The back of the green drains towards the cart parking/access route to the green. If drainage naturally flows away from traffic, the back swale can drain more area.

Draining the back of the green is harder, since the slope drains at about 90 degrees to the line of play, but still must slope toward golfers to provide the visibility/shot holding functions for the back of the green. With less room to work with at the back of the green, golfers need even more help for those tighter back “Sunday Pin” targets. I have found:

• The back swale should exit the green edge about a foot higher than the front one, to keep the entire green sloping uphill, and to prevent crowned greens.
• With fewer shots landing above the hole, green backs can slope more than the front, from 2-3 percent.