The pilot reported that during initial climbing out, while under tow, the glider's canopy became loose. Despite his attempts he was unable to lock the canopy. As a result of trying to lock the canopy, he lost sight of the tow airplane so he elected to disconnect the tow rope about 300 feet above ground level. The pilot stated that he had to use his left hand to hold the canopy closed during flight and was unable to deploy the spoilers. Without use of the spoilers and a tailwind, the pilot aborted the approach due to the glider traveling too fast for landing so he turned right in an attempt to land on a perpendicular runway. During the landing, the glider encountered additional lift and bounced upon touchdown. The pilot elected to land off-field to the right of the runway. During the landing sequence, the right wing struck a tree and the glider landed hard, which resulted in substantial damage to the wings and fuselage. The pilot reported no preaccident mechanical malfunctions or failures with the glider that would have precluded normal operation. The pilot further reported that he failed to ensure the canopy was locked during the pre-takeoff inspection.