The first two important factors in reading the green are its contours and its speed. Contours are the slopes and undulations which do not change. The pin position and the location of the ball will determine which contours will concern you. Look for the overall slope and drainage patterns in the surface – in many greens be aware that rainfall can come off the surface in several different directions. You need to work out only what will affect your putt on this green. There will be more contours on larger green and these can be gradual, strong, uniform or variable.
There are several types of contours. A deck is a flat area where the pin can be placed. Undulation is an area with several elevation changes in wave like form. The multiple changes in the degree of slope will affect the distance and direction of the putt. A bowl is a small depression on the green. A putt entering a bowl must allow for increased speed gained from the bowl’s downslope. Putting out of the bowl you will need to hit the ball with sufficient force to negotiate the bowl’s incline. A swale is an area of low lying, meandering green which generally slopes towards the edge of the green to ease drainage. The pin isn’t usually put there.
Speed is related to turf conditions, the type and grain of the grass and the weather. It can vary during the day. Speed can be measured by a stimpmeter, a metal device with a groove.A ball is rolled down the device onto the flat part of the green and then a measurement is taken how far the ball rolls. Slow greens are less than 7.5 feet, medium are up to 10 foot and fast is anything above that.Wind, sun and heat affect the speed of greens as does mowing and irrigation. Rain, fog and dew will decrease speed. The next element is the grain of the grass, identify the direction in which the blades of grass are growing – dull appearance the grain is growing away, will slow the ball down. Shiny appearance, the grain is growing towards the sun and will make the ball run faster.
The types of grass on the green will affect the speed. Many greens have a combination of grasses, for example when fast growing poa annua invades a bent or fescue green. The main types are Bentgrass – which grows in cool climates. It is a grass with fine blades which grow upright and often causes the ball to run fast. Bermudagrass grows in warmer climates and has a lot of grain. The grass grows horizontally and is generally slower than bent. Fescue grows in cooler climates and grows in groups with the blades developing sporadically. It creates slower greens and lacks a prevailing grain direction. Zoysia has very strong blades and appears in areas of Japan. Kikuyu grass will appear around a greens on some American courses. It tangles the club and is difficult to chip out of. Poaannua is a cool season grass which is bushy and a lighter green than bent. It creates a rough, bumpy surface and many greenkeepers try to control or eliminate it.
On the green look out for unrepaired ball marks, they can be mended under the rules without penalty. They will affect balls roll and cause it to bounce off line. Go to school on others putts watch how the contour and speed affects the ball’s journey. Observe how your own approach shot reacts as it rolls across the putting surface. It will help to bend down and have a look at the line near the hole, although the Camillo Villegas method is not recommended, I always marvelled at how he managed to do this in such tight trousers.