While conducting a cross-country flight, the pilot encountered deteriorating lift conditions, and an outlanding became necessary. The pilot reported that while he was on short final approach to the selected paddock he encountered strong lift, which caused him to overshoot the target touchdown point. During manoeuvring for another approach, the glider stalled and struck the ground in a very steep nosedown attitude. When it was apparent that the aircraft would overshoot the target touchdown point, the pilot had carried out a steep turn to re-position for final approach. During this manoeuvre the spoilers, flaps and landing gear had been left extended. The pilot had evidently not monitored the airspeed and the glider had stalled and probably entered an incipient spin. There had been no requirement for the steep turn to be undertaken, as a landing straight ahead was available.