I have two rubber plants (trees?) That are growing quite well. I think I want to prune them and start other plants before they get way too big. They aren't very bushy and full but the leaves are very healthy. One of them has a red swell growing on the side - is it trying to start a new plant?

I read that I can cut off 12" or so with leaves attached to start a new cutting, but the leaves on my rubber plants have such long loping stems I'm not sure that would work? Air layer???? Thank you for the help.

Looks more like a Philodendron to me, not a rubber tree. Looks like it needs more light. Yes, stem cuttings will root in a jar of water. Gene

Absolutely Philodendron. The swell may be a flower bud forming.

I agree, Philodendron, not Ficus and it appears to be a climbing type of Philo. You could give it a trellis or moss pole to climb but you should be able to easily root cuttings also. I never have luck acclimating cuttings with water-roots to soil; water seems to produce thin, watery roots and when I go to pot them up in soil, they always seem to struggle as they try to establish a stronger root system ... but many folks do have success with rooting cuttings in water.

If it were me, I'd cut the stem at the level where the green twist tie is, remove the lower leaves from the cut stem and stick the stem/stalk into a well draining potting medium. Keep the soil just moist but not soaking wet, give it bright light but no direct sun and keep it in a warm and humid area. I'm not sure this is the best time of year to propagate cuttings; with our humid climate here in Florida I've rooted cuttings in fall and winter but I've heard folks in other parts of the country say that the best time is spring.

For comparison:
Rubber Plant (Ficus elastica)
Blushing Philodendron (Philodendron erubescens)

Well said. I would wait to see what the swell is first. I've not had any failed cuttings of Philos with aerial roots like that. They're ready & anxious to go.

Your Philodendron is naturally a vining or trailing plant and requires a lot of staking if you try to keep it upright. Tip cuttings with 3 or 4 leaves and one bare node at the base of the stem are the best candidates to root in either damp potting mix or water. You could probably insert the cutting in the base of the existing pot if you want. This is a tropical plants so it doesn't matter what season it is when you propagate it.

The red section is the sheath that covers a new leaf that is about to emerge.