You can pot the cuttings up either way. I often loop long cuttings and try to get as many points of the vine in contact with the potting mix as this gives you the fastest root system. Short cuttings with developed roots like this could easily be laid across the potting mix to take advantage of those roots. Really what ever method you choose the cuttings will be happy either way. The roots that are above the potting mix will dry up once they are in a lower humidity environment but this will not affect the health of the cutting.

Mike

Thanks for answering another of my questions. Even though I'm getting rid of these, to save space I'd prefer to plant them vertically in smaller pots. I just wanted to make sure that the roots that are left above ground would harmlessly dry up. Someone else suggested dividing each cutting into smaller 1 or 2 node cuttings. I guess that would also work but they'd be awfully tiny.

I put my cuttings in a large plastic baggie to root them and they grew long, white roots as a result.

I have H. Linearis and H. Polyneura - what's left of them - growing in a large baggie. And both are showing signs of new growth and roots growing above the soil line! Mike is right. You can pot them either way.