I think the plastic bag is your problem. Here is how I do it. First I get my pot ready, I use Pro Mix, a commercial soiless potting medium, mostly peat and vermiculite and get it good an wet and pat it down and let the excess water drain. I then take the cuttings, dip the bottom in water then the rooting hormone, then take something slightly bigger around as the cuttings and stick that in the potting soil to make a hole so I can insert the cutting without the hormone being scraped off by the soil. I then insert the cutting and pat it down. I then put the pot in a bright shady place and keep the soil moist. Not wet. It is my belief that if you give them too much water it doesn't encourage rooting.

I have about a 90% success rate doing it this way. It works on green and brown cuttings.

X

animated,
here is advice i received when enquiring on how to propagate Quisqualis indica (Rangoon creeper which is also a vine) from cuttings:

Use cuttings of firm new growth. Apply 0.1% IBA (rooting hormone) stick in well drained soil & mist.

maybe it will help you although i suspect it would be a good idea to find out how to propagate each vine- i am no expert but figure there is a difference or at least rec way to do it with dif vines. what vines are you trying to propagate? in any case, don't give up!
dory

My greatest success has been the same for any cuttings I root: sand - nothing but sand. Fill a CLAY pot with regular potting soil, set a smaller CLAY pot inside the soil and fill with sand.

Set both pots in a saucer filled with water. Dip your cuttings in water and rooting media, then use a pencil to make a hole into which you stick the cutting. Press the sand in firmly around the cutting, water the SAND pot well, and set it in a totally shady area.

Keep the saucer filled with water, which the clay pots will 'wick' up, keeping both soil and sand moist. This works 90% of the time for most cuttings. REMEMBER: keep the saucer filled with water!

Well, can you tell us what KIND of vines you're trying to root? I have some things that I root in water, some in soil, others in florists' foam. And some things that I can ONLY root by layering!

Here's what I do with about 50% success rate.

After the vines have sat in water for some time, I take each one out and make a diagonal cut at the rooting end and then dip into rooting hormone. After that, I place the cuttings into a vermiculite/perlite potting mix and place the cuttings in partial shade for the first two weeks.

Making a diagonal cut at the rooting end exposes more "tissue" to the rooting hormone. Thus, increasing the chance for the rooting to grow.

Placing the cuttings in the shade seems to initiate a survival mechanism in the cuttings and also initiates rooting to take place. It also keeps them from drying out if they're in direct sunlight.

I also "mist" the potting medium with a blend of Super-Thrive and water about every other day.

These techniques seem to work really well for me. I also had some limited success placing a heating pad under the potted cuttings. Supposedly that
also triggers some growth mechanism in the cuttings. As I said, I had limited success with that technique.

Good luck and happy growing.