I transplanted my very vigorous rhubarb patch about 5 years ago and it has been weak and spindly ever since. The bottom leaves yellow off and die. I have added peat and manure and fed the thing but it will not revive.
It usually takes 2-3 years after planting or transplanting for rhubarb to become vigorous enough to yield enough stalks to both harvest and feed the plant over winter. However, five years seems like a long wait, especially when it’s receiving lots of nourishment.
If, during transplanting, some of the root was damaged or the crown was allowed to dry out, it might take a bit longer to recuperate. Rhubarb is relatively trouble-free, but it does require sun and good drainage in order to thrive. It also doesn’t do well if it has to compete with shrub or tree roots. If any of these conditions aren’t met (for example, if it was moved from ideal conditions to less-than-ideal conditions), you could have an unhappy rhubarb plant.
Rhubarb can also develop a few problems. Poor drainage, or a long, wet spring can create the conditions for fungal diseases such as crown or root rot, which eventually results in the total collapse of the plant.
For more information on rhubarb see the following https://www.rhubarb-central.com/transplanting-rhubarb.html