Certified GKH Gardening Expert
You didn't mention the size of your plants, but you'll want to create a hole in the soil two times wider than the root ball. The root ball should be planted level with the ground, and it will need a deep watering. Be sure to allow at least two to three feet of space between your yucca and any other plants. One source suggests covering the plants with a shade cloth until they begin to grow.
Here's an article on how to care for Adam's Needle: