Grafting onto seedling root-stocks of normal vigor can result in specimens that grow out of character. This seems more likely to be the common situation than larger than expected plants being produced by using the largest pieces of dwarf stock plants.

I specifically asked if my plants were grafted because I was aware of the vulnerabilities of non-grafted lawsonianas. I was told they were not and I decided to buy them anyway. I could not at the time find any evidence of a graft, so I have to assume they are not grafted plants.

However, I did err in suggesting that 'Elwood's Pygmy' was the victim of growers who selected cuttings with too much vigor. In fact it was 'Elwoodii' I referenced. Here is a copy/paste text from the ACS website:

Chamaecyparis lawsoniana ‘Ellwoodii’ is a staple of the nursery industry, a familiar, neat cone of bluish green juvenile foliage when young. It is also a good example of what becomes of a nice dwarf conifer if overzealously propagated. By taking only the strongest cuttings for propagation, the plants grown now are much more vigorous than originally intended. Plants grown in the 1920s would only grow to heights of 3 feet (1 m) or so after 25 years, all the while maintaining tight juvenile foliage. Now it’s typical to see plants reaching heights of 4.5 feet (1.5 m) after only 10 years on to unbelievable dimensions of 15 feet (5 m) or more after 10 years with foliage coming close to adult form

I just presumed Elwood's Pygmy suffered the same fate. I have no doubt that mine will easily be at 15' or more at 10 years of age :-( :-(

My pic was taken in the mid-Atlantic and here is how these plants finish up around here therefore I don't recommend them.

I am about ready to take mine out. They are just HUGE. And planted in a small front of the house bed. What a waste .....