Very slow to establish has been my experience.....

Mine took about four years or so to really get going and now it gets to be about seven feet tall.

Mine is second year also and, disappointedly, still very small. But it appears very healthy, happy where it is, and I'm hopeful for next year.

How much sun is yours getting? I have 3 of them. The two that get a decent amount of sun are three times bigger then the one that is in mostly shade. When I say sun ... I mean I have echinacea,day lilies, rudbeckia, etc in the same beds.

Maybe 3-4 hours. I thought this is a shade plant - ?

I would try more sun then. Move it in the fall or spring (whatever does better in your area). My big ones are 6 hours at least. They don’t burn for me... and don’t start to wilt any sooner then the echinacea right next to them.

All of mine are still grown and getting bigger still this year... but right now that are ...

4 hours ... 2 foot wide

6+ hours ... 3 feet and 3.5-4 feet. Wide

I have one that gets less than four hours, more like two, and it is in its second year. Planted last fall. It is a little over 2 feet tall now. Maybe yours had a weaker root system and is just having to develop that? Who knows.

I'd be thrilled with 2 feet at this point.

I should add that I really worked on having beautiful soil when it was planted. The bed was new and the soil that was there was basically builders junk from almost 30 years ago with that many years of whatever happened to decompose on it, which wasn't very much at all. I added high quality compost (I compared the analysis sheets of the compost near me and chose the one with the highest nutrients) and peat to the soil, making it nice and fluffy for root growth. It's possible those additions helped my plant along.

I have three other aralias, all bought late last summer, and they are about the same, all in good soil. Maybe it was their size at the time of purchase. The only place that had them at that time was a froufrou nursery for the more...blessed...among us. They were in pretty big pots, definitely bigger than the standard gallon pot. They were roughly 3 feet when purchased. Could that be it, as well?

Maybe 3-4 hours. I thought this is a shade plant - ?

It is definitely a "shade plant". It is my experience that 3-4 hours of sun would be lots.

(Our best specimen gets at most 2 hours of direct sun and it is close to 4 feet in height at this point in the season)

I would recommend giving it another year, going with the old gardening adage of "first year it sleeps, second year it creeps, third year it leaps." If you move it again this year, you may end up starting that cycle all over again.

I have 14 Sun Kings and I can say the ones that receive more moisture, do far better than those in drier soil.

Here is the larger one of my 2. Year 3 and finally growing...the other still isn’t doing much.

I have 14 Sun Kings

Wow!