Transplanting established plants can unrealistic, you are talking about a mass of very delicate runners, roots and shoots which are difficult to access and tricky to move, unless you can find one growing intact starting in a pot of dirt which can be lifted onto a truck
There's a narrow window of opportunity in Spring to find tubers which are just starting into growth before they start to run and form new growth as long thin runners
Waters will still be bitterly cold at this point, 40's temps, when waters are warm with growing temps, the delicate runners will be romping away from the wintering tuber a couple of feet per month
Set too deep and lotus will grow like a waterlily with pads on the surface of the water, when they do put up aerial stems from such a depth any breeze or storm is likely to blow them about for lack of stability, When the heavyish blooms form more often than not they will be keeling over and going splat in the water
There may be a reason why they become expensive or hard to find, after Spring. To get a division in suitable condition to transplant may destroy umpteen other runners to find one that can be separated...
Regards, andy
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