ottonowak: Do you mind advice from the colonies? :-) First, you have chosen the trickiest of chores, unless you have very sandy soil (and then, it's still tricky). The reason is that the tentacle-like roots are nearly impossisble to lift in their entirety, and cutting them with a spade presents the possibility of disease entering the open wounds. Don't be deterred by that--I've moved them in the past, with good luck; just wanted you to know that possibility does exist. Three-year-old crowns may have roots half a meter in length--and spreading (and intertwined) with the others that you say are very close--so, therein lies the difficulty. Nevertheless, it still can be done. Unless you have very mild Winters in your location, you should do it in very early Spring--before they awake from dormancy, and begin their growth. Asparagus should be lifted and transplanted while dormant--attempting it while they're in leaf (fern) WILL set them back and MAY kill them. You could do it after they go dormant in Fall if your Winters were quite mild; but harsh Winters may freeze the newly cut and transplanted roots, so best to wait 'til early Spring, when the weather will be constantly warming (instead of the reverse). In my area, Asparagus poke through the soil April 1 (nearly to the day), annually, so I would dig them BEFORE that date, while they are dormant. With the warming weather of Spring, the roots will take hold and grow on, once transplanted. BUT, it is wise to note and MARK the Asparagus you wish to transplant, in the Fall. Why? Harsh Winter winds may dislodge the dried asparagus ferns, and leave no evidence of where they WERE. I use a bamboo skewer (from the kitchen) to mark the location of each crown I wish to dig in Spring; then, even if dried ferns have blown away, I know exactly where to dig. If you are moving (and transplanting) Asparagus to a nearby location, the job is somewhat simplified. The idea is to dig a spadefull of soil containing the crown and as much of the roots as possible, and place them in their new location. As I stated, if it's nearby, it's easier. I once moved 100 Asparagus crowns 40 kilometers for a lady who had sold her family home in the city, and wanted the heirloom Asparagus (planted by her grandmother) moved to her newly-constructed home in the country. I don't know the variety of the Asparagus, but they were HUGE--much larger than Conovers Collosal--the largest I had ever seen. I once weighed 6 Asparagus spears she gave me at 504 grams--over a half-kilo, and, each, approximately 5 centimeters at the base of the spear. All male plants--her grandparents had removed the (seed producing) females. I might suggest to you to do the same if you're interested in spear production (as opposed to seed saving). Male plants produce larger spears--the females use much of their energy producing the red berries (that contain seeds). She told me she wanted the crowns transplanted at her new home at ANY cost. I...

Thanks Marylandmojo... that's VERY helpful. I think I will try it despite your warnings. We have pretty mild winters here in London so I hope they might survive. Thanks again - great advice!