Yours is doing as good as any of mine did the first year. The planting directions sound good. The "Starfish" like roots like to be barely under the surface and care must be taken when weeding or the roots can be damaged. every year the roots will grow further out from the plant. Robustus I think is a relative term!!! Al

I don't have Robustus (I don't think, I have 5 white & 2 yellow). The foliage really doesn't get very big, but wait for the flowers. They will be much better next year. Mine were hurt by late frost, but are getting ready to bloom. The flowers get over 5' tall on the white, a bit shorter on the yellow, for me.