I reckon they stand a better chance as planting into an existing bed means they will be exposed to a lot of old rotting rhubarb roots which may encourage rotting in the new root damaged by transplanting. I never have any problem transplanting rhubarb into new ground, it’s seems to be one of the hardiest things around.

Sunny but only 6 degrees again

I bought a couple new roots of Valentine rhubarb a couple months ago. Pickings were slim at the garden center but I found 2 scrawny roots that seemed to show more life than the others. I direct-planted them to fill some gaps in the rhubarb bed, amended with compost and kept them moist. 

There was nothing showing after a month, so I found a much larger (more expensive; variety Crimson Red) root at a different garden center. Planted it the same way.

Today, I determined the more expensive had rotted. Meanwhile, the Valentine scrawny roots have at least sprouted.

I think the issue might be that straight planting in the ground, it is difficult to evenly control moisture. Sometimes I get rot, sometimes not. I hope I don't need to fill in again, but if I do (next year), I was thinking of putting roots in pots of open but moist compost & sand and setting them in the open door of the garage (light, but no rain). I can control the moisture, and not risk things getting soggy/rotting. When the plant gets some size to it, I can plant it out.

Do you think I will get better survival this way?

My old plot was very heavy clay. Before I ammended the soil with huge amounts of compost and greengrow I used to grow my root veggies by:
1) Using a long spade to draw a long, thin, deep trench by jabbing the blade deep in the ground and rocking it back and forth to make a v-shaped trench.
2) I'd then fill it with cheap compost and pack it in firmly.
3) sow into the compost so the delicate tap roots could grow down quickly without hitting hard clay or stones.

I got decent size parsnips and carrots like this.

Wrapped Cat- The Vibrators