I've transplanted crowns several times BUT only tried it once with crowns that old and it was almost a total loss. The root systems are just too massive to withstand the trauma no matter how much care and TLC you use.

Instead I would trim down the ferns in the existing bed to reduce/eliminate the shading. That late in the season you can trim their length by half with no harm to them.

JMO

Dave

Thanks for the input Dave. Thats what I was looking for. My ferns get to be 6 feet tall. If I cut them back to 3 feet or so, just wondering if I will have any "fern" left or just woody stalks? But I guess by then enough energy has been stored in the crowns so a hard cut back may not be an issue.

We had a patch of "wild" asparagus that was decades old in front of our house. The county did some road expansion and dug it all up.

I noticed the asparagus crowns trying to grow there the dirt was all piles up during the road work, so I dug them out and replanted them somewhere else. I had fat marker size spears the next year! Good thing too, because they hauled all that dirt away.

I've dug up established asparagus during the late fall when it's dormant. All top growth was dead for the season. No root pruning or any special care except of course to make certain the new bed was deep in rich compost and a 6 inch layer of leaves was on the soil for the first winter to protect the roots. They grew perfectly fine without a hitch.