Everytime I see those even in expensive nurseries they always look thin, frail and sickly -- is this just normal for them? I like the look and color of the leaves but it always seems like there are so few of them. I saw them for $10 at my local H.D. too.

Silk tree always has sparse branching, so when a specimen is small it can look pretty minimal. After it develops the lack of density in each portion of the tree is compensated for by the greater overall volume.

Perhaps due to the way recent springs have been I am seeing quite a bit of die-back on local silk trees. As usual this generally consists of whole secondary branches inside the outer canopy drying up, although so far this year I have seen at least one instance where a dead branch went all the way to the outside, resulting in an unpleasant gap.

What you want for these is a hot sunny spot with good drainage. Like many other purple foliage variants the purple silk tree does not maintain the springtime level of pigmentation through the whole season, on every site.

Actually, from what I've read about 'Summer Chocolate', the purple pigmentation behaves the opposite of other purple-pigmented plants. Usually, new growth is purple, then fades to green. 'Summer Chocolate' actually does the opposite - new growth is green then turns purple, with the height of color occuring in the summer, hence the name.

'Summer Chocolate' is not as winter-hardy as the species, and the species is less hardy than the cultivar 'E.H. Wilson'. Consider this when choosing the site. Choose a protected site in full sun, and consider mulching the roots in the winter.