How to build a putting green using modified techniquesYou are ready to build a putting green but your analysis of the soil conditions indicate you need to carry out some modifications. The technique you need to use is to build what is generally known as a modified green and the type of greens the majority of golf courses today are working with. If your soil is fairly sandy to loamy, just had poor infiltration rates, you may get away with simply adding subsurface drainage and making sure your surface allows excess water to easily drain away from the green. On the other hand if you have very heavy soils with lots of clay, you may need to add drainage and then either mix the existing soil with sand or prfereably use the existing soil for shaping the surrounds, and bring in better material for the green. Just a few explanations of terminology often used: The rootzone is the soil below the turf in which the roots grow in. The greens mix is a soil that is brought in from off site to be used for the rootzone in the event the existing soil is inadequate. Let’s start with the shaping the green. If a greens mix needs to be brought in, you will need to count on a depth of at least 12 to 14 inches in order to easily cut a hole. In extreme situation were cost is prohibitive, you could get away with as little as 6 inches, however, the drainage needs to be set lower to be sure the cup cutter doesn’t hit it. Also, later, when cutting cups, be sure that the two layers do not get mixed up, you want to keep the heaviest soil at the bottom. If you are simply adding drainage, then you can shape the green as described in the traditional method , if you are replacing the rootzone, shape the bottom of the excavated green the same as you want your final contours. When you build a putting green the shape is very important, you need to be sure that surface water can drain away from the green, preferably in more than one location. Ideally your high point will be in the middle of the green and the surrounds do not drain onto the green. Too much water is detrimental to the green, so you want to have as much control as possible over how much Mother Nature decides to add. Also you have to think about pin placements. Anywhere within a pin length (5 to 7 feet) of a slope greater than 4% should not be used for a pin placement (it becomes like a mini-putt course then.) What is slope? You need have some way of determining the elevation differences and it is simply calculated by dividing the elevation difference (rise) by the horizontal distance (run) multiplied by a hundred and is the form of a percentage. For example a change in elevation of 10cm over a distance of 5 meters (500cm) gives a slope of 2% ((10÷500)x100) which is acceptable for a pin placement. Remember the general shape you create now will be the same as the final shape as you build a putting green.
Continue to Part 2 of Modified techniques for putting green construction For more information or specific questions on building your green, contact me!
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