Golf Course - Putting Green

The putting green, or simply the green, is an area of very closely trimmed grass on relatively even, smooth ground surrounding the hole, allowing players to make precision strokes on it. To "putt" is to play a stroke on this surface, usually with the eponymous "putter" club, which has very low loft so that the ball rolls smoothly along the ground, and hopefully into the cup. The shape and topology of the green can vary almost without limit, but for practical purposes the green is usually flatter than other areas of the course (though gentle slopes and undulations can add extra challenge to players who must account for these variations in their putting line), and typically does not include any enclosed hazards such as sand or water (though these hazards may be - and often are - placed adjacent to the green).

The green is typically surrounded by slightly higher grass (cut about the same height as that of the fairway), and then by rough. This longer grass between the green and rough is known as the fringe and is designed to slow and stop balls rolling along the green from an approach shot or errant putt, preventing them from exiting the green. Though putting strokes can be made on it, the higher grass can interfere with the path of the ball, so players often choose to use a lofted club such as an iron to make a "chip shot" or a "bump and run", where the ball carries in the air for a few yards and then rolls along the green like a normal putt.

The grass of the putting green (more commonly just "green") is cut very short so that a ball can roll for a long distance. The most common types of greens for cold winter, but warmer summer regions (i.e., not extremely warm, as in the Southern and Southwestern United States) are bent grass greens. A green may consist of a thin carpet so that bad weather is not allowed to become a serious factor in maintaining the course. These are considered the best greens because they may be cut to an extremely low height, and because they may be grown from seed. Bent grass does not have grain, which makes it superior as a putting surface. However, bent grass may become infested with poa annua, a costly and time-consuming weed. Augusta National is one of many golf courses to use this type of green. The original design of Augusta National did not include bent grass greens, but in the 1980s the controversial decision was made to convert the greens from Bermuda to bent grass. This has affected the speed and playing of Augusta National. Many other golf courses subsequently made the decision to change from Bermuda to bent grass when they observed increased business at courses that had already changed over. Another type of grass common for greens is TifDwarf Hybrid Bermuda (other variants exist, but TifDwarf is one of the most common), or simply Bermuda grass. Bermuda is more common in regions that have very warm summers and mild winters, such as the Southern and Southwestern United States. Red Bridge Golf Course was the first course in North Carolina to utilize a special Bermuda called Mini Verde. A green is generally established from sod which has had the soil washed off of it (to avoid soil compatibility problems) and which is then laid tightly over the green, then rolled and topdressed with fine sand. Another common and more economical approach for establishing a putting green is to introduce hybrid Bermuda spriggs (the stolon of the grass which are raked out at the sod farm), which are laid out on the green. The best greens are always established vegetatively and never from seed.

Two downside factors of Bermuda greens are cost of maintenance, and also the existence of grain (the growth direction of the blades of grass), which affects the ball's roll and which is called "the grain of the green." The slope or break of the green also affects the roll of the ball. The hole, or cup, is always found within the green and must have a diameter of 108 millimeters (4.25 in) and a depth of at least 10 centimeters (3.94 in). Its position on the green is not fixed and typically is changed daily by a greenskeeper in order to prevent excessive localized wear and damage to the turf. A new hole will be cut by a device that removes a plug of the turf from the ground, and the reinforced cup is then moved, before the old hole is filled in with the plug cut from the new hole and levelled. The hole has a flag on a metal pole positioned in it so that it may be seen from a distance, but not necessarily from the tee. This location marker is officially called the "flagstick" but is also commonly referred to as the "pin.".

Putting greens are not all of the same quality. The finest-quality greens are well-kept so that a ball will roll smoothly over the closely mowed grass. Excess water can be removed from a putting green using a machine called a water hog. Golfers describe a green as fast if a light stroke on the ball makes it roll a long distance; conversely, on a slow green a stronger stroke is necessary to roll the ball the same distance. The exact speed of a green can be determined with a stimp meter. By collecting sample measurements, golf courses can be compared in terms of average green speed. It is, however, illegal by the Rules of Golf to test the speed of a green while playing by rolling a ball on it, or by feeling or rubbing the green.