Stemme S12-G Pilot reported shutting off the fuel selector valve while in glide flight. During the return flight; altitude was too low so the Pilot restarted the engine. After five seconds the engine quit; forcing the Pilot to land on a golf course fairway with landing gear only partially extended; damaging the aircraft.

Narrative

I was doing a sight seeing flight out of ZZZ1 Friday afternoon. Around 5;000 feet I entered a thermal and turned off the engine. Shortly thereafter I had a very faint fuel smell in the cabin so I turned off the fuel selector valve; something I have never done before while soaring. I flew northeast of ZZZ while monitoring ZZZ Approach and ZZZ Tower. Traffic was busy. I notified ZZZ Tower that I was the glider they were reporting traffic about. I also had traffic on two screens on my panel. ZZZ reported to me that there were multiple IFR jet flights arriving shortly into ZZZ at my altitude which probably was around 3;500 feet at the time.At that point I turned back west and descended to get below arriving traffic. As I approached [the mountain peak] I was getting too low; turned back east and started the engine. I was in a down draft at the time. I gunned the engine which suddenly stopped 5 seconds later. I had forgotten to open the fuel valve selector in that urgent situation. The only option to land at that point was on the fairway of the Golf Course. There were two fairways to choose from. One had 3 carts (14th fairway) and the other had only one cart (15th) off to the right side. I put the landing gear switch to the down position; pulled full spoilers and landed on the grass. The gear had not extended at that point and retracted back into the fuselage. The right wing tip hit the ground and the plane spun around into the opposite direction. No injuries. The gear was surprisingly undamaged; but the gear doors were damaged. The right wing tip was also damaged. The surrounding terrain was very hilly and rocky; and I suspect the outcome would have been fatal if the fairway was not accessible.Bottom line: I turned off the fuel cock which sits above and behind me; and I never have done that before. I got distracted and too low; and got myself into a situation where my check list could not be used. Lesson learned. 1. Start the engine much earlier when you are not in a situation where options are limited. 2. Don't sight see in crowded airspace. 3. Have an emergency start sequence memorized and practiced before every flight. I'm a better pilot than what I demonstrated last week; and I have been kicking myself ever since. Thankfully once again; no one was injured.