I'm a big fan of shoving cuttings into containers with very damp soil. Then I put the pot in the shade and hope for the best. The containers do get lots of water so they stay moist. I do expect that some of the cuttings won't root, and sometimes that's more than half, but I'm always happy with what I do get.

When you do see active growth on the cuttings you'll know that they've rooted, however that doesn't mean that the roots are big and strong--often they're very delicate and quite small. If you can, do leave the cuttings in their container for a few months after they've rooted so they can develop good roots, then transplant them to a holding bed in mid-autumn where they should stay for the winter. Then next spring you can put them where you like in the garden.

Hydrangeas are water lovers, so keep them well watered. Even in the shade, winds, heat and humidity can dry them out very quickly.
You might want to put a bit of bark mulch on top of the soil in those pots. It will help to keep a bit of the moisture in the soil, help keep weeds from getting in the soil and filling up the pots with their roots.

Whatever ones root I would plant in a somewhat sheltered area just for the winter and would do it in mid Sept. in your zone. I'm zone 5 New England and mid Sept. is safe to get them in and give them time to establish a bit in their new temporary home before the cold hits. If it stays warm like it did last fall, then you have extra time for their roots to get comfortable, if it doesn't, mid Sept. is plenty of time for them.

Fran

Climbing hydrangea are best propagated by taking advantage of the roots they put out all over their stems. So lay the stems on the surface of the soil and press in - you could use little loops of wire to hold them tight to the soil.

For the penstemon cuttings that you put in the wet soil, I would suggest putting the top halves of soda bottles over them, with the caps off. It will keep the humidity up so the foliage doesn't wilt.

Thanks for the replies, everyone! It seems that moist soil is the way to go for the hydrangea? The ones I put in water yesterday have actually had the leaves perk up, while the ones in wet dirt are still very sad-looking. Yet I know that some things root better in dirt than water.

Does anyone have advice regarding the clematis, or an opinion on the pentemon seed heads?

Thanks again!