The glider pilot reported he was about five miles from his destination airport and had enough altitude to make the field, but encountered sink and was unable to find additional lift. The pilot decided on an off field landing in a large open grass field. During the landing the right wing tip hit the tall grass which resulted in a ground loop when glider was still several feet above ground. The nose yawed to the right and the glider impacted terrain nose first. The wings, fuselage and empennage were substantially damaged. The pilot added that the accident could have been avoided if he had focused more on his choice of a landing spot and that he should have avoided landing in a field with tall grass.