take some cuttings , wrap them in damp paper towels and put them in plastic bags, then in cardboard box. i'm sure u can fit that in a car WITH dogs :). you'll be able to root them, so you will have at least some continuance.

the rest - am not sure. certainly not by post (mail). POD? possibly..if you pack them with paper for insulation and punch holes in the cardboard they should be able to take a week even in very hot conditions. just water them well a couple of days before you pack.

put paper towels on top of soil around the stems - to keep the soil from spilling out and then

I would wrap each pot in a grocery plastic bag, tying up around the stems if possible. even if it's not tight, the paper towels will prevent stuff form spilling out.

how tall are the stems? do you have stakes of some sort? you could try wrapping the whole pot with brown craft paper like a cylinder to protect the long vines. if you have extra boxes, put each plant in it's own box. if the plants are tall: tape 2 boxes together (1 upside down) to create a taller box. stuff with scrunched paper and put a large plastic bag on top loosely. plants transpire in transit, so the paper will absorb the moisture.

if the pots are small (up to 6"), it's much easier to pack them.

how large are your plants and how many are we talking about?

I don't have too horribly many. That is a great idea to take cuttings in case the worst comes to the worst. It's the guys with trellises I'm most concerned about - I think wrapping in a brown paper cylinder is a great idea. I probably would have forgotten about making sure the boxes have air holes. Thank you!

that is not a large amt at all :). they can easily fit in 3-4 book-boxes with cutouts to carry them. I have transported up to 6 boxes on back seat in a car over sev days. the advantage is that you have a/c in hot weather and heat in cold. and you can bring them in for the night if it's too cold.

what I do is put them in floral sleeves (like they have in supermarkets: they are stiff and hold up. but regular long grocery bags will do in a pinch. they are closed-bottomed so no spills in the box, but they don't protect the leaves as well. best to pack pots tight in the box, then no shifting and no spills.

alternatively, i'd just take one box into a car of most hard to get varieties. and take cuttings of the rest. and by the way then you can remove the trellis, as the plant will be shorter.

in general the stems are stiff enough not to break. but untangling them is another matter.

so separating into sleeves works like a charm.

for soil spill I do the following: shred some paper or even cut some tissue paper by hand .

and stuff it on top of soil, then seal with a few strips of scotch-tape across the pot. or use torn up paper towels instead and tape them across. they will absorb moisture in transit.

I’ve packed my hoyas, or any vining plant for that matter, in poster packing tubes bare root. It is really stiff so they will be protected for sure. I could imagine you could put one on each end to double up. I recently packed a Really long Retusa coiled up in an old pencil box.

Good luck! I grew up near Knoxville and moved to NY! Luckily I didn’t have any plants at that point!

barerooting is a lot of work and it damages roots a lot. but that said , you can also remove some soil gently ((may be up to a half ) without barerooting and stuff whatever's left in ziplock bags (as many as would fit) that would keep the soil moist over a week and lighten the load. it would probably be best to put them flat, in long flat box then (like for electronics), as the base will be vulnerable and can snap if put vertically.

poster packing tubes is an interesting idea for young plants with flexible stems. I find that as plants get older the stems stiffen a lot and it's not so easy to move them.