Huglekultur needs time to mature?

Early this spring I built my first hugleculture in a place on my property that warms and melts early. I built it with leftover slash from 1/2" to 2" in diameter and covered it with mud from the swamp. I then planted rhubarb in it. after a decent start I noticed that they were becoming wenie, and by June they were pale green and insect eaten. I abandoned the pile as dead and useless, especially since the rhubarb in the regular garden was doing well.
Yesterday I walked past the mound and to my surprise the rhubarb had established itself! I guess a hugleculture bed needs to be left a year before planting.
I did notice that the rhubarb on the very top is not growing. should I just be patient and wait for it to fill in, or should I plant something else on top?

I think by adding manure when building the pile or possibly by adding compost to the top when built, the aging step might be avoided. I planted right into my buried wood beds and the plants did well, but I used a LOT of old sheep hay and chicken bedding when I built them. You might try adding some compost or aged manure around the rhubarb that isn't doing well, and see what happens.

That is a good idea. I have my first sheep now, so next spring I will have good top dressing.