Please show us some pictures, state your geographical location and tell us the names of the cultivars if possible.

I had (note the word had) the variegated "Samobor", it was a dud. Wimpy is a good way to describe it.

Interesting that 'Samobor', which only has a dark splotch on otherwise green foliage grew rapaciously for me. To the point where I needed to cull out extraneous seedlings before they took over. I would describe its habit as "thuggish" rather than "wimpy" :-)

Different environment, perhaps.

I haven't grown it myself, but I've heard some good things about G. maculatum 'Espresso' in terms of its durability and vigor. I grow plenty of the straight species G. maculatum (which is also a common native woodland plant around here), and it's pretty carefree, but I don't know if the dark-leaved version suffers from any of the weaknesses seen in other species/hybrids and their cultivars.

Espresso! Yeah--that's one of them. I did some comparison on the Bluestone website (good ol' Bluestone) and it appears that the green varieties tend be be "full sun to mostly shady" while the darker leaved varieties say "Full to part sun." So, I think I found the problem. There's also an implication that perhaps they need more water than their green counterparts. I love that chocolate leaf color, but it doesn't seem worth it. I moved one variety (forget the name) to a full sun position and we'll see what happens. Thanks, everyone! Just for fun, here's my all-time favorite (green) Bevan's variety.

My dark ones never did well either...shovel pruned them.