Q.yucca transplanting
How is best when wanting to move long established plants? These are about 20 yrs old and I would like to move them to a sunny spot, the trees have become very large.

Certified GKH Gardening Expert
For most plants, the best time for transplanting is when they are in a dormant state, or Fall. Although yucca are very tough plants, moving them during the extreme temps of the summer is ill advised.
Here are a couple of articles you might find helpful:
https://www.gardeningknowhow.com/ornamental/foliage/yucca/transplanting-yucca-in-garden.htm