yucca

[clarkie]

i have a 12ft yucca in my back garden and want to prune it by approx 4ft as it blocks out alot of sunlight from my garden and ideas??

[Clanad]

This, from Orchard's Edge:

The best time to prune your yucca tree is after the flowering ceases. At that time you can cut the branches back to where they meet other branches or meet the trunk. Hopefully, they will help the tree fit to the size you want it.

If you are cutting long limbs, remember to make several cuts. Cutting a heavy limb right at the trunk may cause it to tear the bark from the stress of the saw.

I would say that if it is growing up that much it may be an indication that it's not getting enough sunlight.  Yucca's generally stay compact if getting sufficient sun, but reach toward the source if insufficient.... Luck!