I agree with Harawlins on this. What I would do is get a lettuce container or any small square or rectangular plastic container from the grocery store, place an inch or two max of potting mix in the bottom half, make a furrow about half an inch deep and lay your stem in it with the leaf sticking out. Forgot to say back fill over the stem.

This should produce plantlets at the cut end and at the leaf (this part will be sticking out of the soil but as it produces more leaves then push it down in contact with the soil so it can develop roots too). Do not over-water the container soil though. If already moist then that may be all you need to begin with. Put the lid on and place under lights or near a sunny window. If it starts to dry out some, add a little water. Once your plant has some size then you can start venting it more and more until the lid is completely removed. You can eventually pot it up when you feel like it then.

Here are a few of my cuttings in large trays, lettuce keepers, etc.

Most in this pan are Immense cuttings that I started in November. I have a couple canes in there along with a rhizome of Bashful Bandit.

The two little pots are of fern spores (I typically put a plastic lid over this tray). Most are Red Umbo leaves that I removed from the mother plant due to their ugliness.

Had a couple spare leaves and a spare pot with no plant in it so...

Ok, this next one is ugly but it just shows you can reuse old Jiffy pellets and the roots of this Zaida leaf have penetrated the mesh liner and looking for moisture and food perhaps.

Once you get some size on them then you can move them up to a bigger pot - I'm using 3 inch pots in this photo.

Here is an example of a strawberry container used to start a leaf of Alligator Alley

And another deeper container with two Freddie plants, a maidenhair fern from a spore, and a variegated watermelon peperomia. These begonias were not from leaf but rather small plantlets from the mother since the mother was quickly dying. After the begonias started growing, they eventually pushed the lid off. These are about a year old now.