I fought tying plants to rocks and drift wood, and it didn't help having large hands. Best solution and the easiest by far, Super Glue Gel (make sure it is the gel type). Place a small drop on the rock/wood, then gently hold the plant against it for a few seconds. Once you put it in the water it will cause the gel to cure faster, though it will also turn white. While the white could stand depending on the amount and placement, will find your plants overgrow it, quickly covering it up. I have seen people use this method effectively to completely cover large pieces of driftwood with moss, while I have used it for anubias and java fern.