Zone 5, the soil really needs to warm up for pennisetums to take off. You're actually borderline on the hardiness for Pennisetum Little Bunny. They may not survive a cold winter in zone 5.

That aside, if they were planted a month ago at the end of April/beginning of May, the soil just wasn't warm enough yet for them to really establish and take off with new growth. Give them a chance now to see what happens during June.

Other than that, if temps, light and water are good, then I usually look at soil issues next.

I live in NC (zone 7), and my Pennisetums are the last of my ornamental grasses to come up every spring, and they don't really take off until the weather gets hot. They also don't seem to be as winter hardy as other OGs.

Thank you for your responses!

I will just leave them alone and hope for the best. They are in a pretty protected spot so hopefully that will help them over winter. It's funny that my Karley Rose seems to be doing well but these little guys aren't. I guess we'll see what they look like in a few months.

Meanwhile, I think my Yaku Jima is going to eat any small animal that goes near it because it is growing so fast and my Morning Light is barely creeping up.

Gardening makes me happy and drives me crazy :-)