I'm trying to grow some semps in gravel, I manually planted each semp at the soil level last season.

My question is, will new pups be able to root on their own? Is the gravel too deep or course for Semps to root in?

The gravel layer is about half an inch deep.

I think the pups will initially survive via their stolons until they establish their own roots. I've seen offset roots along the top surface or traveled down into dressing/growing medium longer than 1/2 inch.

It is great to hear that they can root through the gravel. That will spare me a lot of work transplanting Semps. Thanks for your reply!

I agree with Bev. They should be able to send roots through your gravel.
The semps in your photos look healthy. How long have they been planted there?
Do you live in the east or west part of WA?

That's great, more confirmation that I won't have to bulk transplant Semps this year!

They haven't been planted there very long. I just moved them there last summer. I was rescuing them from a full shade location. Most of them got sunburn in the process, but it seems like they've recovered well.

I live in western WA. So it looks like we live in similar climates.

Your being in western WA makes it much easier to grow semps. They will appreciate full sun. I look forward to seeing how they do for you.